INTRODUCTION: The
March Message attempts to address a variety of topics of current
concern to Massachusetts and other northeastern fruit growers.
It is not a formal publication, thereby allowing the authors
to express opinions that might be withheld from formal publications.
It is divided into two parts. The first part deals with topics
and opinions having general bearing on pest management. The second
part deals with problem pests.
In 1995, we saw the addition of Apollo and Provado, and in 1996 the addition of Agrimek and Savey, to the pool of chemicals available for use on apples and in some cases, other tree fruits as well. As a brief review, these are the crops, pests, and times of application for which these new materials can be used:
Apollo (clofentezine) against immature European red mites on apples, pears and peaches. Application at half inch green to tight cluster on apples. Not labeled for use on plums.
Provado (imidacloprid) against leafminers, leafhoppers, aphids (except woolly aphids) and San Jose scale on apples and against pear psylla and other sucking pests on pears. Application at petal fall to within 7 days of harvest. Not labeled for use on peaches or plums.
Agrimek (abamectin) against leafminers (eggs and larvae) and mites (motile stages) on apples and against pear psylla and mites (motile stages) on pears. Application at petal fall in combination with a horticultural spray oil (not a dormant oil) to 2 weeks after petal fall for best results on both apples and pears. Not labeled for use on peaches or plums.
Savey (hexythiazox) against mites (eggs and immatures) on apples and pears. Application at pink on apples and petal fall or soon thereafter on pears. Not labeled for use on peaches or plums.
As of this writing (February 1997), there is strong prospect that a new miticide for apples and possibly other tree fruit will be labeled for use in 1997. Its common name is pyridiben and it will be marketed under one or more of 3 trade names: Pyrimite, Oracle, or Sanmite. It is effective against immature and adult red mites, two-spotted spider mites and apple rust mites. A single application within 2 weeks of petal fall can provide season-long mite control. It can also be used as an effective rescue treatment against high mite populations during July or August, effectively bringing such populations under control within 1 week. Besides cost, its greatest shortcoming appears to be its fairly high toxicity to mite predators, possibly making it incompatible with an IPM approach to mite control (but we need to learn much more about its benefits and shortcomings before forming any strong opinions). It appears as though pyridiben might be an effective substitute for Omite, though not as safe on beneficials as Omite.
There are 3 other products which
could be labeled for use on tree fruit in 1997 but more likely
will not be labeled until 1998. These are: Spinosad,
Comply, and Confirm. Each of these will have greatest
use against lepidopterans such as leafrollers, leafminers and
codling moth.
UPDATE ON SECOND-LEVEL IPM
STUDIES IN COMMERCIAL ORCHARDS
Our second-level IPM applied research
program in 1996 was focused on 86 of the 102 commercial orchard
blocks used for our 1995 program. Of the 86 blocks, 43 were designated
as second-level IPM blocks and 43 as grower-managed first-level
IPM control blocks. Each block was about one-third acre. As
was true for 1995, all blocks received first-level IPM practices
during April and May. From late June to harvest, second-level
blocks received no pesticide. Instead, we conducted a second
year of research on the potential value of habitat management,
behavioral control and biocontrol practices as a substitute for
pesticides. Here, we briefly summarize our findings on apple
maggot, rose leafhoppers and mites.
For apple maggot flies, in
32 of the 43 second-level orchard blocks and in 8 of the first-level
blocks, we conducted a test comparing the effect of attractive
synthetic fruit odor (butyl hexanoate) versus no odor on capture
of apple maggot flies on sticky red wooden spheres and on ensuing
injury to apples. We also compared the effect of pesticide-treated
red wooden spheres versus sticky red wooden spheres in providing
fly control. Our results show that about 3 times more flies were
captured on odor-baited than unbaited perimeter sticky spheres,
which is consistent with our 1995 findings. Captures on interior
monitoring traps were about the same in blocks receiving baited
sticky spheres or insecticide sprays, whereas captures were slightly
less in blocks receiving unbaited sticky spheres but much greater
in blocks receiving pesticide-treated spheres. Injury to fruit
was least for blocks that received baited sticky spheres (0.7%),
somewhat greater for blocks receiving insecticide sprays or unbaited
sticky spheres (1.1-1.3%), and greatest for blocks receiving pesticide
treated spheres (3.7%). Combined results indicate that baited
sticky spheres were equal to or even slightly superior to insecticide
sprays in providing fly control whereas pesticide-treated wooden
spheres were inferior. Our 1996 version of pesticide-treated
wooden spheres will need improvement before it can be competitive
with sticky spheres in controlling apple maggot. Specifically,
we need to improve the longevity of fly feeding stimulant (sucrose)
so that spheres can better withstand rainfall without losing effectiveness.
For rose leafhoppers, we
repeated the test in which second-level blocks were arranged to
be different distances from multiflora rose bushes, the principal
overwintering sites of rose leafhopper eggs. There was no difference
in grower pesticide-use practices between second- and first-level
IPM blocks during the time of rose leafhopper adult immigration
(from early June to late June). So, for the purposes of our research,
data from second- and first-level blocks were combined. Results
showed that blocks having rosebushes at 50-100m or 100+m from
the block received in total about 60% and 37% as many immigrant
rose leafhopper adults as blocks having rosebushes at 0-50m.
Across 1995 and 1996, our findings suggest that distance from
rosebushes can have a substantial impact on extent of rose leafhopper
immigration, and that such immigration can be reduced by about
two-thirds if all rosebushes within 100m of the orchard perimeter
are eliminated by cutting or treatment with herbicide.
For mites, we worked in cooperation
with Jan Nyrop of Geneva, New York to study (for the second year)
the extent of establishment of mite predators (Typhlodromus
pyri) seeded in 6 first- and 6 second-level IPM blocks
in May of 1995. Several recent years of study have shown that
these predators are naturally present in fewer than 10% of Massachusetts
orchards. Experience in other states and countries suggests T.
pyri has more potential for providing consistent long-term
suppression of pest mites than any other predatory mites due to
its better ability to withstand both low winter temperatures and
certain harsh pesticides such as carbaryl and benomyl. In July
and September of 1996, we took samples of foliage in the 12 predator-seeded
IPM blocks as well as in 12 companion IPM blocks not seeded with
predators. All samples were sent to Geneva, New York for quantification
and identification of mite predators. Results showed that by
July 1996, T. pyri had become established in 42% of the
blocks in which they were released compared with 0% of the blocks
in which they were not released. By September, they were established
in 75% of the seeded blocks. T. pyri was detected in 100%
of 4 other IPM blocks in which they were released in 1992. Evidently,
it takes about three years from the time of seeding until firm
establishment. We will continue to track the degree of establishment
of T. pyri in all of these blocks in 1997.
UPDATE ON DEVELOPMENT OF
PESTICIDE-TREATED SPHERES FOR CONTROLLING APPLE MAGGOT
In 1996, we continued to make progress toward effective pesticide-treated spheres (PTS) as a substitute for sticky spheres for controlling apple maggot. Graduate student Xingping Hu was responsible for most of the progress on trap design. We have been working on 2 quite different designs of PTS: a re-usable wooden sphere coated with a mixture of pesticide, fly feeding stimulant (sucrose) and residue extending agent (latex paint) and a biodegradable starch/sucrose sphere coated with pesticide and latex paint.
Some hurdles must be crossed before either type of sphere can be labeled by the EPA for grower use. First, we must have an orchard-labeled pesticide that is very effective in low amount in killing maggot flies. Second, the manufacturer of that pesticide must be willing to ask the EPA for an extension of the label to include application of the pesticide to PTS. One might imagine this ought to be a simple thing, given that the amount of pesticide on spheres used to control the flies would be 2000-3000 times less than the amount used to spray an orchard. But with the EPA, nothing is simple. Third, in the case of the biodegradable spheres, we need an IPM-oriented company that is willing to buy the license to manufacture the spheres and then to produce them for sale. Finally, we need to show that after hanging the spheres in early July, they can provide excellent protection of apples against maggot flies without needing any further attention for the entire growing season, else the cost of labor required to attend to the spheres (for example, replenish the feeding stimulant) might exceed the cost of fly control using insecticide sprays.
In 1996, we evaluated several newly-labeled orchard pesticides in combination with red latex paint and found that microgram for microgram, Provado was just as effective as our standard dimethoate in killing alighting maggot flies. In 1997, we will field-test PTS having Provado vs. dimethoate as fly killing agents.
In 1996, we compared the effectiveness of dimethoate-treated wooden spheres versus sticky spheres for controlling maggot flies. In 8 commercial orchards, sticky spheres proved superior to wooden PTS receiving 2 coats of paint: first coat contained sucrose, flour and paint; second coat contained dimethoate and paint. Problem was that all the rain during summer washed away the sucrose, leaving little or no feeding stimulant after about 2 weeks. In Prokopyís small orchard in Conway, wooden PTS proved just as good as sticky spheres in providing fly control. Each of these spheres was drilled with 14 holes (1/4 inch diam, 1/4î deep), evenly-spaced across the surface. Holes were filled with sucrose, after which the sphere was coated with paint containing dimethoate. By so doing, there was a continuous supply of sucrose that seeped through the paint to the sphere surface. This type of wooden PTS holds promise provided the drilling and sugar-filling of holes can be done in winter, when there is more time available.
We did not test the biodegradable
starch/sugar version of PTS for maggot control in 1996 but plan
to do so in 1997.
UPDATE ON DEVELOPMENT OF
PLUM CURCULIO TRAPPING STIMULI AND TRAPS
Plum curculio (PC) is the only key
insect pest attacking apples in North America for which there
exists no reliable method of monitoring adult abundance and activity
in orchards. In 1995, we began to explore a variety of pathways
that we hoped would eventually lead to development of an effective
trap for PC and hence an effective monitoring tool. We further
pursued these pathways in 1996 and herein present a summary of
our 1996 findings. Full reports on each of these pathways are
given in a series of articles in the Winter 1997 issue of Fruit
Notes. If research on other species of weevils can serve as a
guide, we expect that it may be several years before a truly effective
PC monitoring trap is developed. This prognosis is underscored
by the fact that research in New England on a PC monitoring trap
can be conducted only for the two-month period each year (early
May to early July) when overwintered adults are laying eggs in
orchards.
Evaluation of Different Positions
of Unbaited Pyramid and Cone Traps in Orchards
In 1995, we tested the ability of unbaited pyramid traps placed between canopies of apple trees in several commercial orchards to predict the onset of PC oviposition in spring. Pyramid traps (also known as "Tedders" traps) were deployed originally in the South for monitoring pecan weevils. They are pyramidal in shape, broad at the base (22 inches), narrow at the top (2 inches), rather tall (40 inches), dark in color (so as to mimic a tree trunk), and capped at the top by a cone-shaped boll weevil trap top, which captures weevils that characteristically crawl upward after arriving on a pyramid. Our 1995 results were not encouraging, showing little predictive capability of unbaited pyramid traps placed between tree canopies. In 1996, we evaluated unbaited pyramid traps as well as unbaited boll weevil trap tops in different positions in a small commercial orchard (Prokopy orchard in Conway), hoping to establish a more effective trap position.
We found that pyramid traps placed adjacent to trunks of apple trees captured at least 5 times as many PCs as traps placed between canopies of apple trees within rows, between perimeter apple trees and woods, or between perimeter apple trees and open field. Pyramid traps placed next to tree trunks also captured at least 15 times more PCs than boll weevil trap tops placed within canopies of apple trees, either on cut ends of vertical twigs, directly on horizontal crotches of small branches, or on mini-pyramids on horizontal crotches of small branches. Further tests showed that the tree-trunk position for pyramidal traps owed its effectiveness not to the greater visibility of such a trap standing on herbicide-treated bare ground beneath the tree canopy but to the distance of traps from the tree trunk. As distance from trunks successively increased, trap captures successively decreased.
From bloom until 3 weeks thereafter,
we recorded daily the number of PCs captured by each trap and
the number of PC feeding or egglaying scars on samples of fruit.
We were hopeful of finding a strong positive correlation between
daily captures (especially on pyramid traps at tree trunks) and
daily injury levels. But we found none. In fact, all correlations
were extremely weak or even negative ones. The bottom line from
these tests is that PC captures by unbaited pyramid traps next
to tree trunks (the most effective trap type and position found
to date) are not reliable as a predictor of incidence of PC injury
on apple trees. We believe that a reliable PC trap will require
use of powerful attractive odor.
Studies on How PCs Approach
Host Trees and Traps
We carried out several studies in 1996 in an effort to understand how PCs approach host trees and traps, so that trap structure and positioning might eventually be optimized.
First, in a small unmanaged orchard at Hardigg Industries in South Deerfield, we wanted to know whether PCs entered host trees by flying, crawling or both and whether mode of entry depended on weather conditions. We coated the trunks of several apple trees with Tangletrap with the intent of preventing PC entry into the tree canopy by crawling (trees were pruned to remove low-hanging branches) and compared PC populations in these trees with adjacent similar trees not coated with a Tangletrap band. Every evening from May 19 to June 7, we tapped the branches of each tree to collect fallen curculios, which were removed from the orchard. Results showed that total numbers collected from each of these 2 tree types were almost identical and that daily numbers from each tree type were positively correlated with daily high temperature.
At the outset, we predicted that numbers would be equal on trees with and without Tangletrap on warm days (signifying that movement into trees on warm days was largely by flight), whereas numbers would be greater on trees without than with Tangletrap on cool days (signifying that movement into trees on cool days was largely by crawling). For two reasons, this did not turn out to be the case. First, on cool days, curculios were not prone to fly or to crawl into host trees. Second, some curculios thwarted by a Tangletrap band from reaching a tree canopy by crawling were subsequently seen to fly into the canopy.
Second, in the same orchard, we wanted to gain a more direct indication of the extent of PC flight into the tree canopy. We therefore positioned 2 squares of clear Plexiglas (2 feet by 2 feet) on a pole about 2 feet to the outside of the perimeter of the foliage of each of several trees: one square at base-height of foliage and one at top-height of foliage. The sticky side of each square faced outside and was perpendicular to the foliage so as to capture PCs flying toward the tree canopy. We captured substantial numbers of PCs on the sticky squares (sampled every evening), and daily numbers captured were significantly positively correlated with daily temperature as well as with daily numbers recorded from evening tappings of nearby trees. This information indicates that on warm days, PCs do in fact fly directly into tree canopies and that on such days they may bypass pyramid traps, possibly accounting for the poor correlation of unbaited pyramid trap captures with fruit injury levels in trees (injuries are greatest on warm days). The great majority of flights onto the sticky squares was during daylight hours. Few occurred during darkness.
Third, beneath some unmanaged apple trees near Prokopy's house in Conway, we compared PC captures by unbaited pyramid traps that received a band of Tangletrap at the base to prevent PC ascent by crawling with unbaited pyramid traps not receiving a band of Tangletrap. Captured PCs were counted daily at 5 AM and 10 PM for 3 weeks from late June to mid July. Results indicated that during daylight hours, about one-third of captured PCs arrived on pyramidal traps by flight and about two-thirds by crawling but during darkness, arrivals were almost exclusively by crawling.
Finally, beneath a plum tree at Prokopy's place in Conway, we released groups of PCs on the ground at 7 PM (temperature was always about 70o F) on 12 days during June and July and observed PC movements for one hour. Releases were half-way between the tree trunk and the perimeter of canopy foliage. Observations revealed that about 40% of the PCs crawled toward the tree trunk or an unbaited pyramid trap next to the trunk (almost none crawled in any other direction), about 15% flew into the tree canopy, and about 15% flew into open space beyond the canopy. Almost none flew onto the tree trunk or onto the pyramidal trap. These observations suggest that at least under evening conditions, PCs move toward the darkest area in their environment (the tree trunk) and do so largely by crawling, especially when the temperature is marginal for flight (70o F or lower).
Combined results suggest that PCs
are indeed prone to fly into tree canopies and possibly bypass
unbaited pyramidal traps during daylight on warm days, meaning
that pyramidal captures on such days may be poor indications of
PC populations in trees. Combined results also suggest that pyramidal
trap captures are much more likely to accurately reflect PC populations
in tree canopies during darkness or on cool days, when PCs tend
to crawl toward tree trunks (and pyramidal traps next to tree
trunks) to enter tree canopies.
Tests of Natural Sources of Odor
in Conjunction with Traps
In tests during late summer of 1995, we found that PCs newly emerged from pupae were captured in greater numbers by pyramid traps baited with whole mature apples at the trap base than by unbaited traps. In 1996, we repeated this test with overwintered PCs. In addition, we evaluated overwintered PC response to traps baited with pieces of mature apples, whole immature apples, male PCs or female PCs.
We found that addition of odor of live PCs (20 per container) to traps had no positive effect whatsoever on enhancing trap captures. This was true irrespective of whether 3 containers of live males or females were placed at the base of a pyramidal trap, a single container of live males or females was placed at the top of a pyramid trap, or a single container of live males or females was place in conjunction with a boll weevil trap top within the tree canopy. This result was disappointing in that we fully expected that odor (pheromone) from at least one of the sexes would attract PCs of the opposite or same sex. Subsequent laboratory tests suggested that when PCs are grouped in small containers (as they were in our tests) they emit stress sounds or odors that repel PCs or at least counteract potential attractive odor emitted by PCs. Midway through our field tests, a journal paper was published by Eller and Bartelt of Illinois describing the structure of a pheromone (grandisoic acid) emitted by PC males that is attractive to both sexes of PC. Synthetic grandisoic acid should be available for testing in 1997 and obviate need for extensive further testing using live PCs as potential sources of attractive odor.
We also found that addition of 16
whole stored mature Fuji apples to the base of a pyramidal trap
did not enhance captures of overwintered PCs. Nor was capture
of overwintered PCs enhanced by addition of a wedge of a stored
mature Fuji apple to the top a pyramid trap or addition of fresh-cut
branchlets (bearing 48 immature McIntosh apples about one-half
inch diameter) to the base of a pyramid trap. Perhaps the quality
or quantity (or both) of odor from these natural sources was insufficient,
or displayed in an inappropriate manner, to attract PCs. We believe
that our best hope for enhancing trap captures through addition
of host odor lies in use of synthetic rather than natural sources
of host odor.
Attraction to Host Plant Extracts
In 1995, laboratory bioassays suggested that PCs were more attracted to odor of McIntosh trees at 1-4 weeks after bloom than before or after that period. Using still-air petri dish bioassay chambers, we conducted more than 3000 trials in 1996 aimed at further pinpointing of the period of attractiveness of McIntosh trees, the structures of McIntosh trees emitting the most attractive odor, and the best solvents for extracting attractive compounds from McIntosh trees.
We found that odor at petal fall
is more attractive than odor at any other stage of McIntosh tree
development. We also found that attractive odor at petal fall
was emitted almost equally as strongly by twigs and leaves of
McIntosh as by the fruit. Water and hexane proved to be about
equally effective and better than other solvents for extracting
attractive odors from McIntosh twigs, leaves and fruit at petal
fall. These findings generally confirm our 1995 results and serve
as a springboard for identifying chemicals comprising the odor
of host trees at this most attractive stage to PC.
Identification of Chemicals Comprising
Host Tree Odor at Petal Fall
In 1996, cooperating chemist P. L. Phelan employed two distinctly different approaches to identifying volatile compounds comprising the odor of apple trees and plum trees at their most attractive stage, petal fall. First, extracts were made of tree twigs, leaves or fruit using water, hexane or methylene chloride as solvents. Second, fruit were placed in a container through which slowly moving air was passed, accompanied by collection of emitted volatiles on an adsorbing surface and then removal of volatiles from the adsorbent by a solvent. Gas- or liquid-phase chromatographic procedures were then used to identify the compounds contained in the solvents.
Approximately 30 compounds were
found and identified, mostly compounds classified as alcohols,
aldehydes, acids or esters. The challenge before us in 1997 and
succeeding years is to determine which particular individual compounds,
or which particular combinations of compounds, are most attractive
to PC.
Future Plans
We are now at a point where in 1997
we can begin to assess the effects of adding attractive synthetic
pheromone (grandisoic acid) to pyramid traps on the ground nearby
apple trees and to cone traps in apple tree canopies. Hopefully,
this will be followed in 1998 by examining trap-enhancing effects
of grandisoic acid in combination with synthetic host odor, provided
we can determine in 1997 which host volatiles are the truly attractive
ones and formulate them for field use in 1998. Throughout these
endeavors, we will continue to study how PCs approach host trees
and traps, in hopes that understanding the nature of PC orientation
to host trees and traps will facilitate improved trap design.
Food Quality Protection Act (FQPA) or "be careful what you wish for, or you might get it". Most growers have certainly heard of the Delaney Clause, a provision in one section (Section 409) of the Food, Drug and Cosmetic Act (FDCA) governing the setting of pesticide tolerances in processed foods when pesticide residues present on harvested products concentrate to a higher level after processing. Another section of the FDCA governed the tolerances set for fresh foods not destined for processing. Over the last several years, many have called for elimination or modification of Delaney and its "zero tolerance" for carcinogens in processed foods. Often, this call has been based on the fact that the capacity to detect smaller and smaller concentrations of pesticide has improved since the clause was first passed into law, and that the clause was "out of date".
To the surprise of many, the 104th Congress amended FIFRA and FQPA in 1996 eliminating the Delaney Clause, and establishing a uniform standard for setting food tolerances for both raw and processed foods that result in a "reasonable certainty that no harm will result from aggregate exposure to the pesticides chemical residue, including all dietary exposures and all other exposures for which there is reliable information." Beginning in the near future, EPA begin evaluating all currently registered pesticides against this new standard, and taking into account several key provisions of the FQPA.
The EPA review will potentially eliminate from registration materials which do not provide a reasonable certainty of no harm based on (1) total human exposure from all uses (e.g., agricultural, structural, public health, etc.), (2) exposure on the part of susceptible populations (such as infants and children), (3) reliance on a common mode of action (e.g., acetylcholinesterase inhibitors), and (4) chronic health flags, including pesticides that act as hormones or hormone mimics. With regard to exposure of infants and children, the review will also take into account pesticide exposure in utero, and may add a further 10-fold safety factor to the 100-fold factor now used when extrapolating from rodent studies to humans in determining a pesticide's "Acceptable Daily Intake" or ADI (now referred to as the "Reference Dose" or RfD). In the short term the EPA Office of Pesticides Programs (OPP) Biological and Economical Analysis Division (BEAD) is expected to focus on a thorough review of organophosphate insecticides, although a recent article in The Grower indicates that carbamates and B-2 carcinogens are also slated for near term review.
Although the EPA is still allowed to register materials if their loss would result in a public health risk greater than the risk from dietary exposure, or if essential to "...an adequate, wholesome and economical food supply", a likely result of this review will be cancellation of certain currently important materials. This may be especially so for so-called "minor uses" (such as all tree fruits), for which the registrant can not justify the expense of required studies.
We believe this is further indication of the need to develop biologically-based IPM systems (Second-Level IPM) which are largely or completely independent of agricultural chemicals. Whether or not changes in the availability of currently-registered materials, or the advent of new safer ones, will occur before second-level systems have been developed and tested for Northeast apples, remains an open question.
Pest Management at the Crossroads
Recently, Consumers Union published a 288-page report called "Pest Management at the Crossroads" authored by Dr. Chuck Benbrook and associates. Quoting from a news release accompanying its publication, the report "analyzes trends in pesticides use, examines the threats these chemicals pose to people and the environment, and tallies the costs and benefits of pesticide regulation. As well, it documents the many successful IPM Programs already in place in agriculture and government agencies." Although many examples given are not tranferable to apple production in New England, the report is a "must read" for several reasons.
First, after stating a clear perspective on the risks associated with pesticide use, the report goes on to strongly endorse "alternatives" such as IPM, and recommends doubling the overall level of federal funding for pest management research over the next 5 years (YEAH!). CU also describes their version of the IPM Continuum, running from "No IPM" to "High or Biointensive IPM". In this view, current Apple IPM systems in common use in New England should be considered "transitional", and represent only "low" or "medium" IPM adoption. High or Biointensive IPM is comprised of systems that "shift reliance from treatment to prevention", and includes scouting and trapping for all major and minor pests and beneficials, monitoring plant phenology, applying pesticides only in accordance with economic thresholds, with pesticide selection and timing to minimize impacts on beneficials and non-targets, scouting to determine thresholds and timing of beneficial releases, multiple steps to enhance plant health and soil quality, and focus on conservation of beneficials and their habitats.
Many examples are given of effective Biointensive IPM approaches for certain pests and certain crops, such as use of cover crops and mechanical cultivation for controlling weeds in vegetable row crops systems. However, on certain soils, cultivation can cause problems with compaction and erosion, and cover cropping alone often is not enough to take care of problem weeds as when moving from growing tomatoes to peppers. Furthermore, relatively little "credit" is given for techniques that reduce resistance development or reduce overall pesticides use (such as using lower than label rates). A main question is whether it is reasonable to set Biointensive IPM as the standard before systems are fully (or even partially) developed.
Growers interested in purchasing copies ($35.95 ea.) can purchase them from:
Professional Mailing and Distribution Services, Inc.
P.O. Box 2013
Annapolis Junction MD 20701
Phone: 301-617-7815
FAX: 301-206-9789
e-mail: pmac@pmds.com
CU also maintains a web site with the complete text of the press packet, as well as several hard-to-find articles and letters on IPM, pesticides and human health, and the new food safety bill (SEE ABOVE) "The Food Quality Protection Act of 1996". The web address is: http://www.pmac.net.
Update on IP (Integrated Production) Certification in the European Union
Previously, we have updated growers on the European Union program of Integrated Fruit Production (IFP). We see this as an example of farmers incorporating ecological principles into crop production, and taking their message to the marketplace. This article is intended as a followup to that earlier information, and is based on a visit this past summer by Ron Prokopy and Bill Coli to the home of IFP, namely the Süd Tyrol (the portion of Northern Italy which was formerly part of Austria), and Switzerland.
IP Certification is based on actions initiated in the late 1960's and early 1970's by the International Organization for Biological Control of Noxious Animals and Plants, West Palaearctic Regional Section (IOBC/WPRS), an international society for the communication of scientific results. IOBC began to define a formal position on the concept and implementation of Integrated Production (IP) and Integrated Farming (IF), and, in 1977, formed a "Commission on Integrated Production", to develop procedures whereby IOBC/WPRS would endorse apple production grown in accordance with the Commission Guidelines. In 1991, the Commission initiated a process to define IP/IF, to describe its underlying strategies, and to establish technical guidelines and standards for its implementation.
They defined "Integrated Production (Integrated Farming) as a farming system that produces high quality food and other products by using natural resources and regulating mechanisms to replace polluting inputs and to secure sustainable farming. Emphasis is placed on a holistic systems approach involving the entire farm as the basic unit, on the central roles of agroecosystems, on balanced nutrient cycles, and on the welfare of all species in animal husbandry. The preservation and improvement of soil fertility and of a diversified environment are essential components. Biological, technical and chemical methods are balanced carefully taking into account the protection of the environment, profitability and social requirements" (Titi, et al. 1993)
Growth of IP adoption, although highly variable from country to country, has been nothing short of exceptional over the past decade and one half , particularly in German-speaking countries and regions such as Switzerland, Germany, and the Süd Tyrol, where up to 84% of fruit is currently IP certified. It is estimated that fully 34% of the European pome fruit production area (@ 322,000 ha) is under IP certification or similar quality assurance (QA) programs.
Major European chain stores (e.g. Migros, Globus) have separate, large sections devoted to IP and organic certified produce, as well as selections of other "green" products. Although some buyers do not pay a premium for IP certified crops, others do, particularly in the Netherlands, Belgium, and Austria. In addition, grower-owned coops (such as "Agrios" in the Süd Tyrol) pay their members more for IP certified. Such premiums, as well as other payments from central governments allowed under the so-called "Green Box" of GATT, by which member countries encourage environmentally-sound practices, often spell the difference between a farm being profitable or not. According to written reports we have seen, such payments amount to 900 ECU/ha/season (Germany), 700 Sfr./ha/season (Switzerland), and 450-800 ECU/ha/season (Emiglia Romagna, Italy). In addition, IP fruit has reportedly been preferentially purchased by retailers in years of large worldwide oversupply, such as 1993.
A number of factors have facilitated
growth of IPM systems in the EU including: a capable and well-organized
scientific community with many individuals working at the forefront
of behavioral ecology, relatively well-educated and affluent consumers,
a well developed and politically active "Green" movement,
relatively small farm size allowing use of practices that might
not be feasible on larger farms, and a pest complex with more
indirect and induced pests rather than direct fruit attackers.
Grower organization as cooperatives, government policies which
reward farmer use of desirable practices and prohibit undesirable
practices (e.g., prohibitions against developing farmland for
housing, subsidies for use of IP and establishment of "ecological
compensation zones", etc.), and government mandates to reduce
pollution also have had the effect of increasing levels of IP
certification.
As noted earlier, IOBC/WPRS has developed technical guidelines for IP of pome (and stone) fruits which have been endorsed, and are binding on all regional organizations seeking or having received endorsement by IOBC. To become a recognized IP certifying body, any regional/national group must follow a well-defined protocol, which includes: studying the IOBC Guidelines, adjusting their own guidelines and inspection system to conform to IOBC standards, completing a full set of application forms, and submitting a fee (1000 Swiss francs). After thorough initial IOBC review, there is a site visit by an authorized representative of the Commission, which may require an additional fee.
Endorsement or rejection of regional/national production guidelines is based on completion of a checklist which either awards points for acceptable practices, takes away points for less desirable, but still acceptable ones, or results in some number of unacceptable sections. Regional/national guidelines can be denied endorsement based their containing a single unacceptable practice (e.g., chemical soil sterilization by fumigation).
A similar checklist is required for evaluating the farm and farm record evaluation system proposed, which also uses the so-called bonus-malus system. For grape growers in Switzerland, for example, bonus points are given to actions which improve fruit quality, result in more biological diversity in the agro-ecosystem, or reduce use of pesticides, fertilizers, fuel, etc. More points are given to actions which have little or no impact on the environment, but no points are given to use of traditional practices ("conventional viticulture") over "softer alternatives". Once again, certain practices deemed to be incompatible with IP objectives receive "malus points" and result in automatic disqualification from IP certification. Growers must keep extensive records on each fruit block, and hand these in to the national/regional certifying body annually. Such records document results of sprayer calibration tests, all pesticide and fertilizer applications, damage from all diseases and insects, levels of beneficial insects, soil test results, irrigations scheduled, and fruit physiological condition.
Under the IP system, key elements
of the IP certification protocol are that: IP systems are clearly
defined by restrictive guidelines; the systems have sufficient
flexibility to satisfy local ecological or economic constraints;
the certification system is voluntary, and provides adequate support
services to participating farmers; participating farmers, advisers,
and research personnel all play an active role in updating the
program; and, beginning and advanced IP growers are expected to
participate in regular training sessions to keep their knowledge
up to date.
PROBLEM PESTS: 1996 ACTIVITY,
NEW FINDINGS, THRESHOLDS FOR TREATMENT
1996 Activity.
TPB trap captures and fruit injury levels were considerably lower
than average in 1996. Many orchards were able to go without prebloom
insecticide for TPB. This is the second year in a row that TPB
has been below average in trap captures and damage levels. A
similar pattern occurred in other New England states and in Quebec.
Could this be the start of a downward trend in TPB populations
on apple? Maybe the TPB parasite Peristenus digoneutis
that has been released in Mid-Atlantic states, New York, and southern
New England has begun to take hold and started to drive down TPB
populations. Nice thought-but donít bet on it.
New Findings. The only new finding of substance is a 1996 report by Bill Day of the USDA that in areas where the exotic parasitoid P. digoneutis has become firmly established since releases began a decade or so ago, populations of TPB on alfalfa (a major host plant of TPB) have fallen by 75%. Good news indeed, and maybe a hopeful sign that within a decade or so, we may see consistently lower levels of TPB in those New England states where this parasitoid is able to flourish.
Regarding insecticidal control,
Guthion, Imidan and Lorsban remain the pesticides of choice, although
Cygon may be preferable in hot spot blocks if applied before half-inch
green (to avoid toxicity to bees). Pyrethroids (Asana, Ambush,
Pounce) usually are more effective than Guthion, Imidan or Lorsban
and are cheaper to buy, but often prove more expensive in the
long run because of the devastating effects of pyrethroids on
mite predators. In fact, a 1996 study by Frank Zalom showed that
7 months after a single application of Asana, Ambush, or Pounce
to fruit trees in California, enough material was retained by
the bark (a favorite resting place of predator mites) to kill
50% of the predators. Even a whole year after a single application,
predator kill was 30%. Without predator mites providing biological
control, an orchardist can hardly escape from using expensive
miticides. Hence, using pyrethroids to control TPB is not only
inconsistent with an IPM approach but could very well cost more
dollars in the long run.
Thresholds for Treatment.
White sticky traps should be placed in the orchard at silver
tip. Traps should be hung at knee level, clear of waving branches
and tall grass. Thresholds are as follows:
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1996 Activity.
EAS was a minor league pest in Massachusetts and other northeastern
states in 1996. Trap captures were well below average in commercial
orchards, as was fruit injury. Whatever EAS larvae that may have
begun feeding on developing apples at petal fall were quickly
snuffed out by petal fall sprays against curculio, which no grower
dared to miss in 1996.
New Findings.
There are no substantive new findings on pesticidal or other
practices against EAS that are currently applicable to commercial
apple production. Ted Turlings and Sylvia Dorn in Switzerland
(where EAS is a native pest of long standing) found in 1996 that
EAS adults were attracted to some volatile compounds emitted by
apple blossoms and may eventually be able to develop synthetic
odor attractants for EAS adults to add to visual traps for monitoring
and perhaps even direct control. Guthion and Imidan remain the
pesticides of choice for EAS control.
Thresholds for Treatment.
White sticky traps should be placed in orchards at pink. Traps
should be at head height on the south side of the tree and should
be clear of any waving foliage or branchlets. Treatment thresholds
are as follows:
1996 Activity.
It was, in 1996, one of the biggest PC injury years in recent
memory. In Massachusetts and other more southern locations, the
major contributing factor was a spell of hot summer weather that
brought out overwintered PC adults in droves during early or mid
bloom. Injury to fruit (especially king fruit) began as soon
as the first petals fell, well before bees were taken out and
insecticide could be applied. But petal fall sprays did an excellent
job of preventing further injury. In more northerly locales,
this early hot spell came too soon to elicit much PC emergence
(trees were still at tight cluster or pink). Injury arose well
after petal fall and was strung out over several weeks on account
of rainy weather that washed off insecticide and delayed PC egglaying.
When PCs are on hand in high numbers during bloom, it's a virtual
certainty that some egglaying will occur at the start of petal
fall (before spraying) if the weather is warm. There's really
nothing that can be done at that time to stop it. The best action
would have been insecticide application at late pink, but that
is 20:20 hindsight and who could have forecast in advance that
such hot weather would come at bloom as it did in 1996? The only
answer to strung-out post-bloom PC activity is maintaining good
insecticide coverage through at least a month after petal fall.
Translation: 3 post-bloom sprays against PC rather than the
normal 2 sprays. Interestingly, warm weather hit during late
pink and bloom in 1995, with similar high incidence of a lot of
early PC injury.
New Findings. In regard to efficacy of pesticides against PC, the most important new information concerns the value of Sevin as a thinner in providing PC control. Peter Jentsch in the Hudson Valley carried out trials of Sevin XLR in 1996 and found that application at late bloom as a thinner provided ineffective PC control, even within the first 3 days after application. Prokopy had a similar finding in his small orchard at Conway. More research needs to be done in this area, but these findings suggest that under the high-pressure PC populations that normally exist in New England, it is probably not wise to count on Sevin as providing very much in the way of effective PC control. Sevin has a short residual activity so that even if some PC control were obtained during the first 3 days, that amount would fade out quickly, especially given the rapid sizing of fruit (and increased amount of unprotected fruit surface) that begins at petal fall. The bottom line: use a normal rate of Guthion or Imidan to control PC even when adding Sevin.
We conducted a large amount of research in 1996 in an effort to develop an effective trap for monitoring and possibly even controlling PC. See above section on "Development of Plum Curculio Trapping Stimuli and Traps" for an expanded presentation of findings. The bottom line is that to date we do not yet have a monitoring trap that will effectively predict whether an apple orchard has enough PCs to merit spraying or to predict when PC injury to apples is about to occur.
Harvey Reissig and Jan Nyrop in
New York have developed a degree-day (DD) model for predicting
optimum timing of PC sprays. After detailed analysis and model
verification, it appears that accumulated DD is not a good predictor
of whether a petal fall spray will be needed but is a very good
predictor of when to apply the last PC spray. They recommend
calculating the number of DD above 50oF (as a base)
beginning at petal fall. The last PC spray should be applied
when 340 DD are reached. Degree days for a single day are calculated
by subtracting 50oF from the average temperature for
that day (i.e. the average between the high and the low temperatures
for that day). Then add the number of DD for each day after petal
fall until a total of 340 is reached. Then apply the last spray.
Glen Koehler in Maine will be working on refining the model in
1997 for New England conditions.
Thresholds for Treatment.
Until an effective trap is developed, the best guide for determining
when to start spraying for PC is to examine fruit as high as can
be reached at the interior of border row trees in traditional
hot spots (or on some unsprayed indicator trees) and spray as
soon as you see a fresh egglaying scar. PC can lay eggs even
in tiny fruit, for example king fruit that have just lost their
petals, even when other fruit in the cluster retains its petals.
Believing that one can wait until fruit sizes up a bit before
spraying can result in real trouble. Keep monitoring for fresh
egglaying scars through the entire PC season and spray accordingly.
But consider giving the 340 DD model a try as a guide for when
to stop spraying.
1996 Activity.
In 1996, AMF captures on sticky red sphere traps in commercial
orchards were much lower than in recent years. Populations of
AMF were extraordinarily high in 1995, infesting a high proportion
of fruit on unmanaged trees. One might therefore have expected
1996 to be a big maggot year. As is often the case, our expectations
proved wrong. Maybe the very dry soil beneath trees in 1995 denied
larvae emerging from fallen apples the chance to find suitable
places to burrow and form pupae. That's about the best explanation
we can think of for the poor AMF showing in 1996.
New Findings.
New findings on AMF largely concern progress on developing pesticide-treated
spheres as a substitute for sticky spheres for direct control,
as reported in the above section ìDevelopment of Pesticide-Treated
Spheres for Controlling Apple Maggotî.
Thresholds for Treatment.
We continue to recommend hanging unbaited sticky-coated red spheres
to monitor AMF and spraying when an average of 2 AMF per trap
has been reached. Traps should be hung by early July. Continue
monitoring in late-ripening cultivars through September.
1996 Activity.
The 1996 season got off to a rocky start for mite control due
to the cold, wet and windy weather before bloom that made it difficult
to get good coverage with oil even for a single pre-bloom application.
At least with respect to the mites, however, we were lucky that
the weather during June and July was cooler and wetter than normal,
conditions unfavorable for rapid mite growth. By August, the
weather heated up a bit and so did the mites, with some growers
needing a rescue miticide application. Many orchards not receiving
harsh pesticides saw high numbers of Amblyseius fallacis
providing good biocontrol of mites in August. All in all, 1997
was a better year than most for surviving the effects of mites
without too much grief.
New Findings and Mite Management Tactics. The recent registration of 3 new miticides (Apollo, Savey and Agrimek) and the recent loss of Omite as a summer rescue miticide has substantially altered approaches to mite management. The challenge now is to effectively weave together all of the following considerations when choosing a management approach: size of overwintering European red mite egg population; types of insecticides and fungicides to be used and their probable effects on mite predators; and comparative cost of materials.
Predators ought to be the foundation upon which all other mite management tactics are built. In New England, we have at present only one truly effective mite predator, Amblyseius fallacis, that is widespread throughout the region. Unfortunately, cold weather during winter usually takes a heavy toll on A. fallacis, reducing it to low numbers by spring. Rarely does it build sufficiently to provide effective biocontrol until late July. But in orchards not receiving predator-harmful insecticides or fungicides, A. fallacis often controls mites well from mid-summer onward. At present, only a few New England orchards are blessed with detectable numbers of the predator Typhlodromus pyri, which is capable of providing excellent season-long biocontrol of mites, even during spring and early summer. Some orchards in every New England state are currently being seeded with T. pyri. But until T. pyri becomes widespread, growers will have to rely on some form of pesticide application (even if just oil) to prevent pest mites from reaching damaging numbers before A. fallacis appears.
The most recent information from research conducted in the Northeast suggests that one or more of the following pesticidal approaches ought to give effective mite control at least through mid-July (and possibly longer) in orchards having insufficient numbers of T. pyri predators: application of Apollo (1.3 oz/100 gal. or 4 oz/acre) in combination with oil (1 gal/100 gal or 3 gal/acre) at tight cluster or early pink; application of Savey (1 oz/100 gal or 3 oz/acre) in combination with oil (1 gal/100 gal or 3 gal/acre) at tight cluster or early pink; or application of Agrimek (3.3 oz/100 gal or 10 oz/acre) in combination with horticultural spray oil (3 pints/100 gal or 1 gal/acre) at petal fall. The per acre cost of Apollo and Savey is virtually identical, whereas the per acre cost of Agrimek is about 40% greater; but Agrimek controls leafminers as well as mites. All 3 of these pesticidal approaches appear to be about equal to one another in effectiveness against European red mites and two-spotted spider mites, but none of them appears to be effective against apple rust mites.
Apollo and Savey have very similar modes of action and should therefore be considered interchangeable with each other in terms of resistance management. In several countries, resistance has begun to appear to each after only 5 or 6 consecutive years of 1 application per year. Therefore, it is highly recommended that growers alternate Apollo or Savey with Agrimek on an every other year basis if these materials are to be used.
Comparison can be made between use of Apollo, Savey or Agrimek in combination with oil versus oil alone for mite control. Several years of research suggest that 2 gal/100 of oil alone at half inch green followed by 1 gal/100 of oil alone at tight cluster or early pink usually suppresses mites effectively until late June or early July, providing 3 or 4 weeks less residual effectiveness than oil combined with Apollo, Savey or Agrimek. Application of 2 gal/100 of oil at half inch green followed by oil in combination with Apollo or Savey at tight cluster or early pink or Agrimek at petal fall aids in mite control where overwintering eggs of European red mites are abundant and aids in control of San Jose scale. But this approach appears to provide little added benefit where overwintering eggs of European red mites are moderate or few. Like Apollo, Savey and Agrimek, oil is safe on beneficials. The cost of a pre-bloom double oil program is about 40% less than the cost of Apollo, Savey or Agrimek in combination with oil.
Research in 1996 overwhelmingly confirms the highly negative effects of synthetic pyrethroid insecticides against T. pyri and A. fallacis. In fact, the bark of apple trees (a favorite resting place of mite predators) has been found by Frank Zalom in California to absorb synthetic pyrethroids to such an extent that 7 months after a single pre-bloom treatment, sufficient activity remains to cause 50% mortality to predators; 12 months after treatment, mortality still is considerable (30%).
Research in 1996 by Jan Nyrop in New York and Noubar Bostanian in Quebec clearly shows that like pyrethroids, EBDC fungicides also have very negative effects on mite predators. Nyrop found that 6 applications of either Penncozeb (at 12 oz/100) or Ziram (at 23 oz/100) spaced 7-14 days apart in May and June reduced numbers of T. pyri by 70% or more at the end of June and that this negative effect continued through the end of the season. In blocks receiving no applications of any EBDC fungicide in April, May or June, but 3 applications of Penncozeb (at above rate) about 10 days apart in July, again T. pyri were reduced by about 70% through the remainder of summer. Nyrop believes that repeated annual reduction of T. pyri by 50% or more as a result of using synthetic pyrethroids or EBDC fungicides is likely to preclude the possibility of gaining effective mite biocontrol by T. pyri. Bostanian did his research on A. fallacis and found that Polyram had little effect on A. fallacis, Nova had a moderate negative effect, and Penncozeb and Syllit had harsh negative effects on A. fallacis. The latter two reduced egg hatch and/or survival of immatures by 70% or more. Several researchers have come to believe that early-season application of EBDC fungicide is more harmful to the survival and reproductive capacity of mite predators, especially T. pyri, than late season application.
Combined information available to date suggests that in orchards receiving even a single application of synthetic pyrethroid insecticide and/or more than one application of Mancozeb or Ziram, T. pyri predators, even after being seeded, will likely be too few to provide effective biocontrol of mites. Such orchards are prime candidates for use of Apollo, Savey or Agrimek in combination with oil. Where insecticides or fungicides deleterious to mite predators are not used and where overwintering eggs of European red mites are moderate or few, a pre-bloom double oil program alone may be sufficient to provide effective mite control until A. fallacis begins to provide biocontrol in late July.
Ideally, a decision on whether or not to apply Apollo, Savey or Agrimek ought to be made in conjunction with sampling information on the population size of motile mites on foliage. Recent research suggests, however, that it is very difficult to obtain a reliable estimate of mite populations when they average fewer than 1 per leaf at pink, bloom or petal fall. Populations reaching or exceeding 1 per leaf merit strong consideration for treatment with Apollo, Savey or Agrimek in combination with oil. Lesser populations may or may not merit such treatment.
In some orchards, rust mites can
build to high numbers by mid summer. Just how high is high enough
to cause injury is unclear. A 1996 study by Easterbrook and Palmer
in England showed that even at average densities of 160 rust mites
per blossom cluster leaf in May, there were no clear harmful effects
on fruit set or photosynthesis. Up to a point, rust mites can
be very beneficial in that they can serve as sustaining early-season
food for mite predators before red mite eggs hatch. In summer,
they could be harmful if they exceed 300 or so per leaf. When
labeled, Pyrimite should provide good control of rust mites, whereas
Apollo, Savey, Agrimek and oil do not.
Threshold for Treatment.
In the 1994 March Message, we presented charts, based on extensive
research conducted in New York, that can serve as a guide to threshold
infestations of mites requiring treatment. We here offer a brief
synopsis of pertinent information from the charts. There is no
solid new information that would suggest altering these thresholds.
| May 15-June 1* | |
| June 1-June 15* | |
| June 15-July 1* | |
| July 1-July 15** | |
| July 15-August 15** |
* Take middle-age fruit cluster leaves
** Take middle-age leaves from anywhere
1996 Activity.
Populations of white apple leafhoppers (WALH) and/or rose leafhoppers
(RLH) seemed fairly normal or even rather low during June in most
of the Northeast but were high at harvest in several orchards
in Massachusetts and nearby states. Potato leafhoppers (PLH)
were considerably fewer than in recent years probably on account
of the wetter weather in May and June in the Midwest, their point
of origin for the long migratory flights to the Northeast.
New Findings.
There were only a couple of new noteworthy pieces of information
on LH that turned up this year. First, some growers who applied
Sevin XLR 2 or 3 times as thinning sprays got good season-long
control of both WALH and RLH. So did growers who applied Provado
at petal fall. But some growers who applied Sevin WP 2 or 3 times
as a thinner did not achieve season-long LH control. Second,
as mentioned in a previous section here, removal or herbiciding
of all rosebushes within 100 yards or so of an orchard block can
cut down on within-orchard RLH populations by 60-70%. This is
a practice that could achieve noticeable benefits at harvest time.
Thresholds for Treatment.
No change from 1996 March Message. For preventing injury caused
by feeding of first-generation WALH or RLH nymphs in June: 3
nymphs per leaf. For growers annually experiencing troublesome
LH populations at harvest, provisional threshold of 25 WALH and/or
RLH nymphs per 100 leaves in June.
1996 Activity.
The pattern of LM populations in Massachusetts in 1996 was similar
to that in other northeastern states. Prebloom captures of LM
on sticky red traps stapled to tree trunks generally were lower
than average and so were numbers of first-generation larvae.
In most orchards, LM remained low throughout the year, but in
a few cases, enough second-generation and third-generation larvae
were on hand to cause some concern. Abundant rainfall gave rise
to vigorous tree foliage and thereby lessened potential negative
impacts of LM in those orchards where mid- and late-season LM
were fairly abundant. One quite consistent observation among
several orchards was the clumped nature of LM mine distribution.
Seems that the windy weather during May permitted LM establishment
primarily in protected sections of orchard blocks. All in all,
though, one of our easier LM years.
New Findings. Although there werenít all that many new IPM-relevant findings on LM in 1996, four types of new information merit presentation here.
First, Kathleen Leahy of Polaris IPM observed that 3 Massachusetts IPM growers under her consultantship who had moderately high populations of first-generation LM larvae applied Provado in mid- to late-June for controlling the second generation. Usually, this would be considered a favorable time for applying Provado against second-generation LM. However, control was judged as poor. Perhaps the take-home message is that optimum timing of Provado application against second-generation LM can be quite challenging owing to the strung-out nature of the appearance of second-generation eggs and larvae and difficulty of knowing when peak numbers have been reached. These findings argue in favor of a petal fall application to ensure a greater degree of LM control, provided one can be confident that LM populations at petal fall can be judged as meriting treatment.
This brings us to the second area of new information: reliability of sticky red rectangles on tree trunks for predicting need for prebloom or petal fall sprays against LM. We found out from more detailed analysis of the data we presented in the 1996 March Message that capture thresholds of 4 or 9 cumulative adults per trap from silver tip to tight cluster or full pink on McIntosh, or 8 or 21 adults per trap from silver tip to tight cluster or full pink on non-McIntosh cultivars are appropriate for apple blotch leafminers (ABLM) but not for spotted tentiform leafminers (STLM). In Massachusetts, ABLM predominates in first-level IPM orchards, and especially so in orchards east of the Connecticut river. STLM predominates in second-level IPM orchards, and especially so in orchards west of the Connecticut river. Apparently STLM adults either move to tree trunks or visual traps stapled to tree trunks differently than ABLM adults do or the timing of their activity is sufficiently different from ABLM to negate the value of sticky red trunk traps as reliable indicators of adult STLM density. This situation merits further study.
In 1996, we conducted a test in 8-acre blocks in 40 commercial orchards on how many sticky red trunk traps are needed per acre to gain an accurate estimation of ABLM adult numbers. For verification, we will repeat this in 1997. But results to date indicate that for an 8-acre block, 1 or 2 traps per block gives a poor indication of ABLM numbers whereas 4 or 8 traps per block gives a good to excellent indication.
Third, Kathleen Leahy of Polaris IPM did careful monitoring of LM mines in the many IPM orchards she scouted and found that 30-50% of larvae in each generation were parasitized by small wasps. In one large orchard that was in full production in 1995 but went out of business in 1996, we saw fairly high populations of first-generation LM mines but, in the absence of any insecticide sprays throughout the year, found virtually no third-generation LM mines. Parasitism was probably the factor responsible for the crash of the LM population. These findings suggest that under relaxed insecticide pressure, parasitism can provide substantial LM control.
Finally, a paper published by Rae
and colleagues in China indicates that 3 successive oil sprays
a week or so apart can effectively deter egglaying by citrus leafminers,
which are close relatives of apple leafminers. We already know
that 3 oil sprays can deter egglaying by pear psylla. So it seems
that just as crop advisor Keith Harbert has been suggesting, 2
or 3 prebloom oil sprays may be providing some measure of LM control
in addition to mite and scale control. To be truly effective,
a film of oil would need to be present on all the foliage as it
expands, especially around the peak of LM egglaying.
Thresholds for Treatment.
Our thresholds are the same as given in the 1996 March Message
with the proviso that they apply to ABLM and less so to STLM and
that they may be unreliable if fewer than 4 traps per 8-acre block
are used (see above). Thus, in Massachusetts we suggest the following:
In a year of above average rainfall,
these thresholds for second-generation mines could be doubled.
LAW is a direct pest of fruit. It is a very close relative of codling moth and oriental fruit moth. In fact, the physical appearance of the larvae of all 3 species is very similar (brown head and pinkish body) as is the appearance of injury (a hole in the fruit surface, with larval excrement covering the entry to the hole). Like codling moth and oriental fruit moth, LAW is rarely seen in orchards practicing first-level IPM because summer sprays against apple maggot usually control all 3 of these moth pests. But in New England orchards under second-level IPM for several consecutive years, LAW is very likely to become the most prominent of all direct pests of fruit. LAW has 2 generations per year. Unlike codling moth and oriental fruit moth, however, its life history is such that it escapes effects of sprays applied against plum curculio.
New Findings.
Rather little is known about the organization of LAW activities
in orchards. But a considerable step forward in our knowledge
occurred in 1995 and 1996 as a result of detailed studies by Chris
Maier in Connecticut. For decades it had been thought that LAW
built up on numerous sorts of wild host plants nearby orchards
and invaded orchards from these wild hosts. Maier found, however,
that of the many wild hosts he surveyed, LAW appeared only on
hawthorn fruit. Orchards with hawthorn trees nearby were susceptible
to LAW invasion, and once established in an orchard, LAW was hard
to eliminate. In fact, once established, both the first and the
second generations of LAW appeared to originate within the orchard
itself. In Maier's judgment, the major contributing factor to
continual presence of LAW in second-level IPM blocks is maturation
of first-generation larvae in drops of early cultivars such as
Paula Red and Jersey Mac. If such drops are not removed, second-generation
adults will arise and infest later-maturing cultivars in the orchard.
Hence, the key to LAW management in second-level IPM blocks might
be attentive removal of drops, especially beneath early-ripening
cultivars and probably beneath all infested cultivars.
New Findings. Agrimek (20 oz. plus 1 gal. horticultural oil/acre) has shown good to excellent control of psylla when applied 10-15 days after petal fall. Thorough coverage is necessary for control, and Agrimek should not be used in less than 40 gallons of water per acre. Recent research reported by Art Agnello in New York showed that withholding a single post-petal fall Agrimek application until 30-45 days after petal fall allows for an early summer build-up of psylla to potentially damaging levels. Delaying the post-petal fall treatment did not extend the residual activity of Agrimek (usually 4-6 weeks) beyond mid-August.
Provado is now labeled for use on pears (20 oz/acre). It has shown good knockdown ability when moderate to high populations are present, but residual control is limited to about 10 days. It appears to be best suited as a late-season application, following a post-petal fall application of Agrimek. As with use on apples, the pre-harvest interval on pears is 7 days.
Mitac is also effective against
pear psylla, but timing is crucial. New York recommends back-to-back
sprays after petal fall: one application about two weeks after
petal fall, the second application about 7-10 days later.
Thresholds for Treatment.
A post-petal fall treatment of Mitac or Agrimek is recommended
if 6-10% of terminals are infested at petal fall.
PEACH BUGS: INSECTS IN
THE ORDER HEMIPTERA THAT FEED ON PEACHES
For decades entomologists have been evaluating peaches that have been damaged by true bugs-insects from the Order Hemiptera. This damage or injury can be as small as a pinprick with or without sap oozing from the wound, or as large as deformation of part or all of the injured fruit, damage most often referred to as catfacing.
There are two groups of bugs that
have been associated with catfacing injury; the pentatomids (stink
bugs) and the mirids (plant bugs). Within each group are several
individual species that cause very similar damage. A description
of each group is given below, followed by a discussion of non-chemical
ways to control these pests.
Plant Bugs.
The most commonly encountered plant bug on peaches is the tarnished
plant bug, Lygus lineolaris. This insect is especially
problematic because it is such a diversified feeder. However,
according to the literature, TPBs do not live on peaches, but
rather prefer to live and reproduce in weedy ground cover or in
hedgerows or fields that are adjacent to peach orchards. Adult
plant bugs fly up into trees early in the growing season. Plant
bugs in the genus Lycocoris have also been reported to
feed on peaches. The white oak plant bug, hickory plant bug,
and other species within this genus are normally found on forest
trees, but can move to peaches in the absence of their preferred
hosts. (NOTE: The white oak plant bug has stronger host preferences
than the other two Lycocoris species, both of which are
also considered omnivores [general feeders].)
Stink Bugs. The other group of true bugs that attacks peaches is the pentatomids, or stink bugs. Three species in particular are usually associated with catfacing injury. These are Euschistus servus-the brown stink bug, E. tristigmus-the dusky stink bug and Acrosternum hilare-the green stink bug. These insects are all highly mobile, and usually remain in the orchard for only a short period of time. Stink bugs, unlike the plant bugs mentioned above, do reproduce on the trees, frequently laying eggs on the lower surface of peach leaves. These eggs are easily identified. They are barrel-shaped, shiny, and appear in clusters containing about 7 eggs each. After the eggs hatch, the young nymphs move down into the ground cover within a short period of time, doing little or no feeding on peaches.
Ecologically, then, since these
critters all feed in the same way on the same crop, there must
be another factor that decreases competition between these species.
That factor is time. There appears to be clear delineation of
who does what when. Research consensus indicates that tarnished
plant bugs are the first to appear in peach orchards, with early
feeding occurring on swelling buds. This feeding can result in
bud abscission. Fruit bud damage, usually caused by Lycocoris
spp. or by TPBs, can result in damaged blossoms. These then fall
to the ground either as damaged blooms or as damaged fruit. The
most severe damage generally occurs between petal fall and the
time when fruits are 1/2 to 3/4 inch diameter. If fruit damaged
at this time fails to fall, at maturity it is heavily scarred
or malformed (catfaced). Numbers of brown and dusky stinkbugs
normally are greatest within a month of shuck fall. Green stink
bug numbers tend to increase throughout the growing season. As
fruit sizes, damage by plant bugs or stink bugs is less dramatic;
holes with gummy exudate or dry corky areas just below the fruit
surface.
New Findings. Both groups of insects share several behavioral traits: It is the adult insects that feed on and damage fruits, with the young of the species moving down into the ground cover; and all species prefer feeding on weeds found in the orchard groundcover or hedgerows, or on other preferred hosts.
These factors lead researchers to conclude that the most effective way to control true bugs on peaches is through manipulation of the orchard groundcover. Studies conducted primarily in southern peach orchards have shown that winter annuals such as wild mustard, chickweed, vetch, dwarf dandelion, plantain, and clover attract and harbor catfacing insects. Many researchers have shown that clovers, alfalfa, and other plants in the legume family are especially attractive to plant bugs. In North Carolina orchards, John Meyer has shown that the elimination of winter annuals through early spring applications of herbicides, discing or by maintaining dense perennial sod makes the orchard less attractive to catfacing insects. Because these insects all overwinter as adults, eliminating late summer weeds will discourage insects from reproducing in the orchard, thus reducing the number of adults that would overwinter and then feed the following spring.
However, since the likelihood of immigration of adults into peach orchards is high, properly timed insecticide sprays should be included in any control program for catfacing insects. Thorough tree coverage is essential due to the high degree of mobility of these bugs. Each insecticide application should be closely followed (within one to three days) by groundcover mowing. Mowing forces the insects to move up into the trees, and therefore fresh pesticide applications are much more likely to control upwardly mobile bugs. Additional research has indicated that plant bugs follow bloom. That is, they move from weeds that have bloomed in the orchard groundcover to blooms on the trees. Therefore, mowing the groundcover before weeds begin to bloom will decrease the attractiveness of the orchard to TPBs.
Groundcover management is only the first step-a giant step- in a catfacing insect control program. Perhaps this giant step toward controlling catfacing insects will encourage your efforts! The next logical step is to evaluate methods for monitoring the incidence of these pests in your orchard blocks. Research has been conducted with several different monitoring methods-sweeping the orchard floor, trapping, limb jarring, etc. In Connecticut a few years ago, triangular traps painted a light pink (peach blossom mimic) were effective in trapping Lycocoris spp. when they were hung either in the tops of peach trees or at the same height in forest trees nearby. Damage to peaches followed capture of the first Lycocoris bug. Traps were not as effective in predicting damage by TPBs, however. Neither sweeping the orchard floor nor visual observation of fruit were shown to be effective monitoring tools in this study.
In a study conducted by Kathleen Leahy here in Massachusetts in 1991 (Fruit Notes, Winter, 1991), pink traps hung high in tree canopies attracted Lycocoris spp. From her results it appeared that there may be a relationship between increased trap captures and catfacing activity. These results were preliminary. Additional research should be conducted if these traps are to be used to develop economic thresholds.
In New Jersey, researchers used sweep net counts of plant bugs to monitor activity levels. They found that early season sweeps net 3-4 bugs/50 sweeps, mid-season counts are 0-2/50, while late season sweeps net 30-40 bugs/50 sweeps. (These results appear to confirm that high numbers of bugs use the orchard groundcover as their overwintering site.)
A study in Michigan compared conventional,
IPM-based and low-chemical IPM-based approaches to peach pest
control. The conventional program consisted of full orchard sprays
applied every other week. The IPM approach consisted of weekly
pest scouting followed by pesticide applications on an as-needed
basis. The low-spray protocol (similar to 2nd level IPM) maximized
non-chemical control strategies such as mating disruption for
oriental fruit moth. Synthetic pesticide use was as follows:
17 sprays in the conventional block, 9 in the IPM block, and
2 in the low-spray block. Insect damage was lower in the low-spray
blocks than in the IPM blocks, but higher than in the conventional
blocks. TPB, however, was controlled using the low-spray protocol-attention
to ground cover management and the use of endophyte-infested groundcover.
The results of this study are encouraging. The common thread
of most of these studies is, however, that groundcover composition
and management is as important in controlling catfacing insects
in peach orchards as are chemical sprays. Proper timing of mowing
along with one or two well-timed pesticide applications may adequately
control these insects. We still need a more thorough understanding
of catfacing insect complexes in Massachusetts orchards, and perhaps
better monitoring methods, in order to develop an IPM strategy
for our conditions.
For 1997, the monthly newsletters,
weekly Healthy Fruit messages, the March Message, the Peach, Pear
and Plum Guide, and the 1996-1997 New England Pest Management
Guide will be available for a subscription of $40.
Subscriptions may be ordered by sending a check for $40 made
out to University of Massachusetts to Karen Hauschild, Box
3099, 212 Stockbridge Hall, University of Massachusetts, Amherst,
MA 01003. Single copies of the March Message are also available
for $5, and may be useful for out-of-state growers as an alternative
to the entire Massachusetts subscription. Copies of the following
publications may be ordered individually from the UMass Extension
Bulletin Center:
A fax service is available
in 1997 for faster receipt of the weekly Healthy Fruit messages.
The subscription cost of the service is $15, payable to the University
of Massachusetts. Requests for subscription and payment should
be sent to Starker Wright, Department of Entomology, Fernald
Hall, University of Massachusetts, Amherst, MA 01003.
A supplement to the 1996-1997
New England Apple Pest Management Guide applicable to 1997
will be mailed to all who subscribe to the $40 package of information.
The guide was edited by Glen Koehler of the University of Maine.
There will be a new version of the
Peach, Pear and Plum Guide for 1997 which will include
updated pest biologies and control methods, edited by Karen Hauschild.
Tree fruit control guides should be used only during the growing season(s) for which they were written. Information obtained from old guides may be incorrect and may result in illegal pesticide application, or growers may miss new information about phytotoxicity or effectiveness. We highly recommend that growers discard old pest control guides in favor of the updated versions.
The 1987 publication "Opportunities
for Increased Use of Biological Control in Massachusetts"
summarizes information on the potential for biological control
of insect pests of apples, small fruits, cranberries, vegetables,
forage crops, greenhouse crops, and woody landscape plants.
Two fact sheets are available on
biological control of mites and leafminers on apples.
Costs:
| 1996-1997 New England Apple Pest Management Guide | $7.50 |
| 1997-1998 Peach, Pear, and Plum Guide | ** |
| Opportunities for Increased Use of Biological Control in Massachusetts
EXPF 0900 0718 | $7.00 |
| Biological Control Fact Sheets: | |
| Apple Blotch Leafminer IPMA 000L 594A | $2.95 |
| Spider Mites in Apples IPMA 000L 595A | $2.95 |
** The 1997-1998 Peach, Pear
and Plum Guide will not be in print until April 1997. Limited
copies of the 1995-1996 Guide are available, at $3.50/copy.
The costs above include production,
handling, and mailing expenses. Checks should be made out to
the "University of Massachusetts" and sent together
with your order to Bulletin Center, Draper Hall, University
of Massachusetts, Amherst, MA 01003. Please use the ID code
(series of letters and numbers) to specify the publication you
are ordering.
Fruit Notes,
a quarterly journal published by the UMass Plant and Soil Science
Department and Cooperative Extension, contains important new research
findings on fruit growing in Massachusetts. The subscription
price is $8.00 ($10, US funds, for foreign subscriptions) per
year, and checks should be made out to "University of
Massachusetts" and sent to Wesley Autio, Department of
Plant and Soil Sciences, Bowditch Hall, University of Massachusetts,
Amherst, MA 01003.
Some additional publications that
include information on insect and disease biology, identification,
or monitoring are:
Tree Fruit Production Guide 1996-97.
Penn State University. Price $13.00. Make checks payable
to Penn State and send with your name, address and the title of
the publication you are requesting to Publications Distribution
Center, College of Agricultural Sciences, Penn State University,
112 Ag Administration Building, University Park, PA 16802.
"New York Fact Sheets".
Tree Fruit Fact Sheets include Pear Psylla, Codling Moth, Plum
Curculio, Green Fruitworm, Obliquebanded Leafroller, Peachtree
Borer, Apple Maggot Fly, Spotted Tentiform Leafminer, European
Red Mite, Predatory Mites, Rosy Apple Aphid, San Jose Scale, White
Apple Leafhopper, Dogwood Borer, Woolly Apple Aphid, Oriental
Fruit Moth, Beneficial Insects, Redbanded Leafroller, Brown Rot,
Fire Blight, Powdery Mildew, Cedar Apple Rust. Excellent photographs.
A set of 30 fact sheets can be purchased for $18.55, prices range
from $1.00-$1.50 for most single fact sheets. These can be ordered
from Resource Center-GP, 7 Business and Technology Park, Cornell
University, Ithaca, NY 14850.
"Pest Management Fact Sheets,"
Cooperative Extension Service, University of New Hampshire,
Durham, NH 03824. No charge. Fact sheets are available on
tarnished plant bug, codling moth, red-banded leafroller, apple
maggot fly, plum curculio, European red mite, two-spotted spider
mite, aphids, scale insects, fire blight and apple scab.
Common Tree Fruit Pests,
published in 1994. A comprehensive guide to identification
and control of more than 50 arthropod pests of tree fruits. Written
by entomologist Angus Howitt of Michigan State Unversity. Contains
many excellent color pictures and straightforward information
on most pests encountered in the field. Available in hardcover
($37.50) or laminated softcover ($30.00) from: Bulletin Office
- TFP, Michigan State University, 10B Agricultural Hall, East
Lansing, MI 48824-1034. Publication is NCR-63 Common Tree
Fruit Pests. Checks should be made out to Michigan State
University.
Mid-Atlantic Orchard Monitoring
Guide. Published in 1995
by Northeast Regional Agricultural Engineering Service, under
the guidence of West Virginia University and with input from fruit
researchers throughout the Mid-Atlantic region. Contains throrough
and current information on pest and disease biology, monitoring
and treatment, as well as nutrition, irrigation and fruit evaluation.
Many color photographs. Available for $75.00 from Northeast
Regional Agricultural Engineering Service, Cooperative Extension,
152 Riley-Robb Hall, Ithaca, NY 14853-5701. Checks should
be made payable to NRAES.
A variety of pheromone and visual
traps is commercially available to growers as insect monitoring
aids. We have had considerable experience with the following
traps as part of our IPM research and extension efforts over the
past years.
1. Pheromone Traps
Leafminers
- Pheromone traps for spotted tentiform leafminer (STLM) adults
have been used in Massachusetts, but they are of uncertain effectiveness
in attracting apple blotch leafminers (ABLM), the predominant
leafminer species in most commercial orchards in Massachusetts.
Codling Moth (CM), Oblique-Banded
Leafroller (OBLR), Oriental Fruit Moth (OFM), Red-Banded Leafroller
(RBLR), Variegated Leafroller (VR), Lesser Appleworm (LAW),
Sparganothis Fruitworm
- Although traps have been used in the Massachusetts IPM program,
these pests are not usually much of a problem and so we have rarely
used trap capture data for management decisions. As part of our
on-going extension efforts, we plan to continue to monitor these
pests closely, as the leafroller pests, especially, may have the
potential to develop resistance to commonly used organophosphate
compounds. Monitoring for these pests will be more important
with a very low spray schedule.
Lesser Peach Tree Borer, Peach
Tree Borer, Dogwood Borer
- Pheromone traps are available for determining appearance and
abundance of adults.
Tufted Apple Bud Moth, Green Fruit
Worm - Generally these
pests have not been a problem in Massachusetts orchards and we
have not used pheromone traps for them in our IPM program. Green
fruitworm was a major problem in a few western Massachusetts orchards
in the early 1980's but numbers have declined in subsequent years.
2. Visual Traps
Tarnished Plant Bug (TPB)
- We continue to experience good results with the sticky white
rectangle traps for TPB. These traps should be set out at silver
tip (no later) and pesticide application need and timing based
on cumulative captures from silver tip to tight cluster or pink.
Leafminers
- Sticky red visual traps, stapled to tree trunks at silver tip,
continue to prove useful in indicating adult emergence and in
predicting need for treatment pre-bloom or at petal fall.
European Apple Sawfly (EAS)
- EAS adults are highly attracted to sticky white rectangle traps
that mimic apple blossoms. Traps should be placed at pink and
the need for pesticide application based on cumulative captures
from pink to petal fall.
Apple Maggot Fly
(AMF)
- Sticky red spheres that mimic ripe Delicious apples are an excellent
aid in monitoring AMF abundance. They are especially helpful
in June and July for determining first arrival of flies in early
variety blocks and in August and September for determining arrival
of late season flies immigrating into blocks of Delicious and
other late season varieties. Traps should be positioned in late
June for early-developing and mid-season varieties and in early-July
for late developing varieties. Sticky red spheres baited with
synthetic apple volatiles developed in New York are 2-4 times
more effective in capturing AMF than unbaited sticky spheres alone.
Traps should be cleaned of insects and debris regularly, preferably
once every 2 weeks, as capturing effectiveness will decrease with
the accumulation of dead insects.
Several variations of sticky red
spheres, including lightweight plastic molded traps, are available
from the IPM products division of Gemplerís.
Pear Pyslla - Sticky yellow traps can be placed 1-2 m from the ground in the south quadrant of the tree to monitor adult activity in spring.
Pear Thrips
- Sticky yellow traps should be set three feet high. We use a
tomato stake and a metal shelf bracket to mount the trap in the
correct position. Traps should be checked at least weekly from
ground thaw until fruit bloom. Current recommendations call for
a minimum of four traps per ten acre block. Monitoring for thrips
populations in nearby overwintering areas, e.g. sugar bushes,
can help to determine the potential for thrips immigration.
3. Tangle-Trap (A Tanglefoot Co. product)
Tangle-Trap (Bird Tanglefoot) is
a clear, odorless, non-drying adhesive that is used to coat the
reusable red sphere trap. Tree Tanglefoot is also a non-drying
adhesive, but it should not be used with the red sphere traps
since it is not clear or odorless.
4. Metos Apple Scab Monitoring Computer
This computer will determine if an
infection period has occurred for apple scab. In addition, it
can be used to calculate degree day accumulations in order to
monitor insect development.
5. Bird Control Balloons
Scare-Eye bird control balloons have
given good to excellent results in reducing bird injury to Cortlands
and other susceptible varieties. One balloon is effective over
a radius of approximately 20 yards.
Suppliers:
Pheromone traps, synthetic apple
volatiles, visual traps, bird repelling balloons, Tangletrap,
and magnification equipment for use in sampling are available
from:
Gemplerís
211 Blue Mounds Road
P.O. Box 270
Mt. Horeb, WI 53572-0270
(800) 382-8473 (Orders)
(800) 332-6744 (Customer Service)
Many pest management supplies are
also available from:
OESCO, Inc. (Orchard Equipment) Great Lakes IPM
Rt. 116 10220 Church Road
Conway, MA 01341 Vestaberg, MI 48891
(413) 369-4335
In addition to the weekly monitoring
and other information provided through University of Massachusetts
Extension IPM, growers are strongly urged to monitor their own
orchards, or hire private consultants to do so.
The Infonet computer bulletin board
system (BBS) is no longer available. However, a new Umass Extension
web page is available on the World Wide Web. The web page address
is http://www.umass.edu/umext/programs/agro. Questions
about the system should be referred to Bert Szala at (413) 545-1043
or 545-2230 or at berts@umext.umass.edu.
Two private consulting businesses
will continue to offer IPM consulting, scouting, and other services
in Massachusetts in 1997. Their addresses are:
New England Fruit Consultants (NEFCON) Polaris Orchard Management
56 Taylor Hill Road 364 Wilson Hill Road
Montague, MA 01351 Colrain, MA 01340
(413) 367-9578 (413) 624-5104
(413) 367-0313 (FAX)