20th ANNUAL MARCH MESSAGE
TO MASSACHUSETTS TREE FRUIT GROWERS (1998)
BY

RONALD PROKOPY, STARKER WRIGHT, WILLIAM COLI and CRAIG HOLLINGSWORTH
DEPARTMENT OF ENTOMOLOGY
UNIVERSITY OF MASSACHUSETTS
Web version translated and edited by Daniel Cooley

INTRODUCTION This is the 20th Anniversary of the March Message. Since its inception, the intent of the March Message has been to summarize new information and offer thoughts related to the management of insect and mite pests in Massachusetts. The March Message is not considered to be a publication, thus allowing the expression of opinion that might be withheld from a formal publication. Ron Prokopy will be on sabbatical leave from late January through late May of 1998. The information presented in the 1998 March Message is therefore perhaps less robust and less complete than in previous years, when writing of the March Message extended through February. This electronic version is largely a direct copy of the printed version, with a few links built into it.

CONTENTS

GENERAL IPM TOPICS AND OPINION
CHANGES IN ORCHARD CHEMICALS FOR 1998
UPDATE ON THIRD-LEVEL IPM STUDIES IN COMMERCIAL ORCHARDS
UPDATE ON DEVELOPMENT OF PLUM CURCULIO TRAPPING STIMULI AND TRAPS
UPDATE ON DEVELOPMENT OF PESTICIDE-TREATED SPHERES FOR APPLE MAGGOT
PROGRESS TOWARD ESTABLISHMENT OF T. PYRI IN COMMERCIAL ORCHARDS
UPDATE ON THE FOOD QUALITY PROTECTION ACT (FQPA): WHAT'S NEXT?
SELF-GUIDED IPM TOUR

PROBLEM PESTS: 1996 ACTIVITY, NEW FINDINGS AND THRESHOLDS
TARNISHED PLANT BUG
PLUM CURCULIO
APPLE MAGGOT FLY
LEAFMINERS
MITES
PEAR PSYLLA
PEACH PESTS

IPM MANUALS, SUPPLIES AND SERVICES
PURCHASE OF 1998 PEST CONTROL GUIDES, IPM MANUALS, ETC.
MONITORING AIDS: TYPES AND PURCHASING
PEST MANAGEMENT SERVICES AVAILABLE IN 1998

GENERAL IPM TOPICS AND OPINIONS

CHANGES IN ORCHARD CHEMICALS FOR 1998

In 1995, we saw the addition of Apollo and Provado, in 1996 the addition of Agri-Mek and Savey, and in 1997 the addition of Pyramite to the pool of chemicals available for use on apples and in some cases other tree fruits as well. In the works for future registration for use on apples and some other tree fruits are Spintor, Pennstyl (formerly known as Plictran), Comply and Confirm. However, new registrations have slowed considerably at the EPA owing to EPA's deep involvement in interpreting and administering the 1996 Fruit Quality Protection Act passed by Congress. Thus, for 1998, we anticipate registration of only Spintor.

Spintor (spinosad) will be intended for use principally against lepidopteran pests, particularly leafrollers. The active ingredients are called spinosyns, which are produced naturally from Actinomycetes (a microorganism). It is primarily a stomach poison, meaning it needs to be ingested to work best. It has fairly short residual activity after application and tends not to be very active against sucking insects such as aphids or leafhoppers. It appears to have moderate but not excellent activity against leafminers. Spintor could be a very valuable addition for controlling pests such as obliquebanded leafrollers, which are a major problem in western New York and several other regions but not a particular problem in Massachusetts.

Pennstyl (cyhexatin) is being redeveloped so that it no longer poses a threat to field workers or no longer appears in excess on fruit at harvest. Its intended use will be as a summer rescue material against mites. It would indeed be a very welcome material that in the past gave excellent mite control in many orchards and was very safe on beneficials. We do not expect this chemical to be registered for use until after the 1998 field season.

Pyramite (pyridaben) is now also labeled for use on pears to control pear psylla as well as European red mites and pear rust mites. Not much information is available comparing pear psylla control by Pyramite versus control by Provado or Agri-Mek.

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UPDATE ON THIRD-LEVEL IPM STUDIES IN COMMERCIAL ORCHARDS

Twenty years of research and extension work in Massachusetts prepared us to embark on a new level of IPM in apples in 1997: third-level IPM. In order to make the leap from second-level IPM (integration across all relevant discliplines, promoting biologically-based control approaches) to third-level IPM (integration of all pest management practices with all horticultural practices), in 1997 we embarked on the first phase of our third-level applied research program, which will span 1997-1999.

Our field experiments of 1997 were centered around performance comparisons of bio-based versus pesticide-based tactics for managing plum curculio, mites, apple maggot and flyspeck on large (M.7) versus medium (M.26) versus small (M.9) apple trees. The composition of New England apple orchards is in transition from large to semi-dwarf to dwarf trees, and neither we nor anyone else in the world has knowledge whether bio-based tactics perform as well on small trees compared with larger trees, upon which virtually all New England IPM studies had been conducted prior to the 1997 field season.

The 1997 third-level IPM experiment was conducted in a total of 48 blocks across 8 commercial orchards. Each of the 48 blocks was square, 7 rows across, averaging 49 trees per block. Of the 48 blocks, 16 were comprised of large trees, 16 of medium trees and 16 of small trees. all trees were mature and bore fruit. Of the 16 blocks of each tree size, 8 were under bio-based management to the maximum extent possible; the remaining 8 blocks were under grower-based first-level IPM management. The following sections discuss results obtained on plum curculio, apple maggot and mites as managed using bio-based versus first-level IPM practices in our experiment.


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PROGRESS TOWARD DEVELOPMENT OF PLUM CURCULIO TRAPPING STIMULI AND TRAPS

Among key insect pests that attack pome and stone fruit in North America, plum curculio (PC) is the only one for which there does not yet exist an effective monitoring trap. In 1995, we began in earnest to conduct research aimed at developing such a trap. Since then, we have conducted as intensive a research effort on PC as funds have permitted. Here, we present a summary of our 1997 findings. Full reports on each of the aspects described here are given in the Winter 1998 issue of Fruit Notes.

Evaluation of Unbaited Pyramid Traps in Commercial Orchards

In 1996, we evaluated unbaited black pyramid traps for their ability to predict need and timing of insecticide sprays against PC in a single small commercial apple orchard in Conway, MA. That study showed that even though such traps in optimum position (next to apple tree trunks) captured reasonable numbers of PCs, there was no correlation between periods of substantial capture and periods of substantial damage to fruit caused by PC. In 1997, we extended this study to eight large commercial orchards in Massachusetts. Black pyramid traps, intended to mimic tree trunks, are currently receiving much attention as potential monitoring devices for PC in peach orchards in the South.

In our 1997 study, we placed 3 unbaited black pyramid traps in each of 6 blocks of apple trees in each of 8 commercial orchards, for a total of 144 traps in all. Traps were emplaced at bloom at 3 positions: next to tree trunk, between tree canopies, and adjacent to the nearest woods. They were examined for PC captures every 3-4 days thereafter for 4-5 weeks. At each trap examination, 105 fruitlets on perimeter-row trees were examined in each block for PC damage.

Results showed that no fruit injury occurred in any blocks prior to the first insecticide treatment shortly after petal fall, even though there were some PCs captured by traps at each position. In every block type (small, medium or large apple trees), fruit injury increased between the first and second, between the second and third, and after the third insecticide application. However, in almost all cases, trap captures either successively decreased from levels that were reached prior to any insecticide applications or were nil throughout. There was no positive correlation between extent of trap capture and extent of damage for any trap position or any size of tree.

The findings of the extensive 1997 study are consistent with the more limited 1996 study: patterns of PC captures by black pyramid traps are poor predictors of need and timing of sprays against PC in apple orchards in the Northeast. Studies toward understanding why this is so and toward developing alternative trap types are described in succeeding sections of this report.

Studies on How PCs Approach Host Trees and Traps

In 1996, we undertook some initial studies aimed at understanding how PCs approach host trees and black pyramid traps. Only one of the 1996 studies involved direct observation of PC movement patterns and that study involved collecting and releasing observed PCs in a somewhat unnatural fashion. In 1997, beginning at petal fall, we made extensive direct observations of movements of PCs toward host trees and black pyramid traps under conditions as natural as possible for typical PC behavior, while still permitting effective observation.

PCs were tapped from tree branches onto a small piece of white bed sheet (a yard square or smaller) held taut on a wooden frame beneath. Apple foliage was scattered across the white sheet to provide hiding places for fallen PCs. It is well known that PCs drop frequently from tree branches to the ground (in response to disturbance by potential predators or unsuitable weather conditions) and then reenter tree canopies sometime thereafter. Our approach simply took advantage of this natural behavior. The sheet harboring PCs was carried quickly but gently to a point midway between the trunk and edge of a nearby tree. There, during one-hour periods spaced evenly across the day, we quietly watched the fallen PCs to see how they behaved.

In the first study, 31% of the 166 observed PCs left the cloth by flight and 16% by crawling. The remainder moved to hide under the scattered foliage or stayed put. Of those that flew, 79% flew toward the tree canopy above or toward inter-tree space. Only 17% flew toward the tree trunk. Of those that crawled, 88% crawled toward the tree trunk.

In the second study, 38% of the 104 observed PCs left the cloth by flight and 18% by crawling. Of those that flew, 74% flew toward the tree canopy above or toward inter-tree space. Only 15% flew toward a black pyramid trap next to the tree trunk and only 3% toward a nearby black pyramid trap at the edge of the canopy. Of those that crawled, 74% crawled toward the trap at the tree trunk and 10% toward the trap at the canopy edge.

Temperatures taken beneath each tree at the time of observed PC movement indicated that no flight but considerable crawling occurred at temperatures of 67F or less.

These extensive observations of the behavior of fallen PCs confirm the preliminary observations made in 1996 and indicate that PC reentry into host trees is exclusively by crawling at temperatures of 67F or less but predominantly by flight directly into the tree canopy at temperatures of 68F or greater. Only a small proportion of PCs flies directly onto the tree trunk or onto an adjacent black pyramid trap. Hence, under warm temperature conditions conducive to PC damage to fruit, most PCs bypass tree trunks and associated pyramid traps and move directly by flight into the tree canopy when reentering trees after falling.

Toward Traps Alternative to Black Pyramids

In an effort to develop traps alternative to black pyramids for monitoring PCs, we initiated preliminary studies in 1997 in which we examined the PC-capturing potential of vertical sticky Plexiglas squares attached to wooden poles emplaced just outside of canopies of apple trees and to non-sticky yellow or black cylinders placed over upright cut twigs inside of apple tree canopies. The 2x2 foot squares of sticky clear Plexiglas were intended to capture PCs flying toward tree canopies from overwintering sites or from nearby host trees, whereas the non-sticky cylinders were designed to attract PCs searching for twigs as resting sites (black cylinders) or for fruit borne on twigs as feeding and egglaying sites (yellow cylinders).

We found that about as many PCs per trap were captured by sticky clear Plexiglas squares as by black pyramid traps next to tree trunks. Importantly, periods of increase in PC captures by the sticky squares were significantly positively correlated with periods of increasing temperature and with increases in fruit damage caused by PCs the following day, whereas captures by black pyramid traps were not significantly correlated with either of these factors. This bodes well for some variant of a trap that intercepts PCs approaching tree canopies by flight as being a potentially effective predictor of PC damage.

We found also that non-sticky black cylinders 8 inches tall by 3 inches in diameter were more attractive to PCs foraging within tree canopies than were black cylinders of smaller diameter or yellow cylinders of similar or smaller diameter. Responding PCs were observed to crawl (but not fly) toward and onto a cylinder, and then to crawl upward toward the top, which was capped by an inverted screen funnel (boll weevil trap top) to capture them.

More work is needed in 1998 to extend these preliminary studies, which we believe do indeed show promise for two different approaches to trapping PCs that are alternatives to black pyramid traps.

Attraction to Host Plant Extracts

In 1997, we again conducted extensive trials using still-air Petri dish chambers to assay responses of PC adults to different structures of McIntosh apple trees in different stages of development. Results confirmed those obtained in 1995 and 1996 and indicated that odor from apple tree fruit and twigs emitted at petal fall and shortly thereafter is the most attractive host odor to PCs. Cooperating chemist P.L. Phelan sent us several individual compounds and blends of compounds that he collected and identified as components of McIntosh fruit or McIntosh twig odor emitted at petal fall. We found at least one compound (Amygdalin) to be attractive to PCs using Petri-dish assays. In 1998, we plan to test all individual compounds and several blends of compounds collected and identified by Phelan as being components of McIntosh odor emitted at petal fall.

Attraction to Odor of Conspecific Adults

In 1997, for the first time, we employed a new and perhaps more sensitive bioassay system for evaluating responses of PCs to odors emitted by conspecific adults in the absence as well as in the presence of attractive fruit odor. The new bioassay system consisted of a box (24 x 24 x 12 inches) constructed of clear Plexiglas into which 10 PCs were introduced at the center of the floor. A source of odor (or appropriate control treatment) was introduced into a small cloth bag hung at each of the 4 upper corners of the box. Under still-air conditions and darkness comparable to conditions experienced by PC adults foraging during calm nights for potential mates within host trees, we examined the extent to which released PCs accumulated at sources of potentially attractive odor.

In trials evaluating all possible combinations of odor-emitting and odor-responding males and females in the presence or absence of attractive fruit odor, we found that the treatment eliciting the greatest degree of response (an average of 60% of all individuals tested) was that of males to females in the presence of fruit odor. When feeding on fruit, females seem to emit a distinctive odor that we could detect by nose and that seems to be very attractive to males. Heretofore, it was thought that only PC males emit attractive pheromone, and indeed we can't yet rule out sound produced by females as having played a possible role in our tests. But the unique-smelling odor produced by feeding PC females leads us to believe that they are emitting pheromone. We plan further studies on this in 1998, and in cooperation with P.L. Phelan, to identify the attractive components emitted by females. Our 1997 lab and field tests using grandisoic acid, a putative pheromone produced by male PCs, showed no significant attraction of either female or male PCs to this compound, giving us impetus to look intensively at how PCs communicate with each other by odor.

Future Plans

For 1998, we plan to continue to study how PCs approach host tree canopies, with an eye toward developing an easy-to-use trap (simpler than a sticky Plexiglas trap) that will attract incoming PCs. We also plan to study further how PCs approach resources within host trees, with an eye toward developing an easy-to-use simple trap (a modification of a tall black cylinder) that will attract PCs after they arrive in host tree canopies. For both types of traps, it is a virtual certainty that attractive odor will be needed to bolster trap power. Toward this end, we plan to evaluate host odor compounds for attractancy and to determine if PC females do indeed produce attractive pheromone.


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UPDATE ON DEVELOPMENT OF PESTICIDE TREATED SPHERES FOR CONTROLLING APPLE MAGGOT


Over the last three field seasons, we conducted studies aimed at development of pesticide-treated spheres (PTS) as a substitute for sticky spheres for direct control of apple maggot flies. In concept, a PTS would be coated with a mixture of insecticide, sugar and latex paint (which extends the effectiveness of insecticide). A fly landing on such a sphere would feed, ingest insecticide, and die before damaging any fruit. The need to use Tangletrap to capture alighting flies would be eliminated. Our earlier trials indicated that dimethoate was the most effective among orchard-labeled insecticides for use on these spheres, but its high human toxicity poses too great a risk to the handler. In 1996, we found that the newly-labeled insecticide imidacloprid is a safer alternative to dimethoate and seemingly as effective.

Table sugar has proven to be by far the most effective fly feeding stimulant. However, while mixing with latex paint preserves the residual activity of the insecticide, all sugar is lost from the sphere surface following rainfall. We have taken 2 separate approaches to preserving residual activity of sucrose:

In 1997, we conducted two experiments leading to refinement of the latex paint and toxicant formulation and evaluation of each sphere type for direct control of apple maggot in commercial orchards.

Evaluation of Sphere Components

In our first experiment of 1997, we evaluated in lab studies three formulations of imidacloprid (EC, WP, technical grade) in combination with each of three formulations (flat, semi-gloss, gloss) of each of four commercial brands of latex paint (36 treatments in all). We found the EC and WP formulations of imidacloprid in Glidden Red Latex Gloss Enamel paint to be the most promising. We then placed wooden spheres coated with two concentrations of each formulation of imidacloprid in orchard trees and evaluated them for their ability to kill apple maggot flies at 0, 3, 6, 9 and 12 weeks after placement.

After 12 weeks of exposure to sunlight and 11 inches of natural rainfall, wooden spheres treated with 1.5% a.i. imidacloprid WP in Glidden paint killed 90% of arriving flies. Such treatment also rendered all flies incapable of laying eggs after feeding, and required that a fly feed on the surface of a sphere for only one minute to ingest enough toxicant to die. Performance of wooden spheres treated with 1.5% imidacloprid EC was slightly inferior, killing 87% of arriving flies. At lower concentrations (0.5% a.i.), neither the WP nor EC formulation performed as well (75% and 45% kill, respectively) as the 1.5% a.i. WP formulation.

This work has provided us with a formulation of a low dose of a safe and highly effective insecticide (1.5% a.i. imidacloprid WP) that can be combined with a particular type of paint (Glidden Red Latex Gloss Enamel) which offers very long and effective residual activity under field conditions.

Evaluation of Pesticide-Treated Spheres in Commercial Orchards

Two sphere types were developed in an attempt to extend the residual activity of sucrose on the sphere surface. Each wooden PTS was fitted with a 3-cm-diameter ring of specially formulated caramelized sucrose around the hook at the top of the sphere. The idea is to have the sucrose spread evenly down the sides of the sphere after each rainfall, continually replenishing the sugar supply on the sphere surface. For sugar/flour biodegradable spheres, the following composition of ingredients proved best: sucrose/fructose syrup (25%), pregelatinized corn flour (25%), wheat flour (25%), glycerin (10%) and water (15%). After hardening in the laboratory, such spheres emit a continuous supply of sugar to the surface, without regard to the amount of rainfall.

The effectiveness of our best wooden PTS and our best sugar/flour PTS were compared with sticky-coated spheres for direct season-long control of apple maggot flies. In all, we used eight orchards, each having four blocks of medium-sized trees (49 trees/block). Each block receiving spheres was surrounded by 26 spheres of the same type 5 meters apart, each baited with butyl hexanoate.

In short, sugar/flour PTS coated with 1.5% imidacloprid in Glidden paint performed as well as sticky spheres (.32% injured fruit) in providing direct control of apple maggot. Wooden PTS coated with 1.5% imidacloprid and fitted with a 3-cm-diameter sucrose ring were inferior (.56% injured fruit). None of the sphere types provided quite as good control as 2-3 insecticide sprays (.11% injured fruit).

Although all sphere types used in the field trial performed quite well in the face of high fly pressure, shortcomings need to be addressed and improvements need to be made before future use of PTS in controlling apple maggot in commercial orchard IPM blocks. Regarding wooden PTS, the caramelized sucrose rings melted away before the end of the field season, contributing to the reduced effectiveness of these spheres. Some of the sugar/flour PTS were eaten by birds and rodents while others were overgrown by fungi on the sphere surface, thus reducing the number of effective spheres comprising the barrier to fly entry into some blocks.

Future Plans

For 1998 deployment of wooden PTS, we plan to reformulate the sucrose ring atop the sphere to improve residual effectiveness of the spheres. For sugar/flour biodegradable PTS, we will evaluate various bird/rodent feeding deterrents and various fungicides incorporated into the body of the sphere.


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PROGRESS TOWARD ESTABLISHMENT OF T. PYRI IN COMMERCIAL ORCHARDS


Pest mites are usually completely controlled by predatory mites on unmanaged apple trees that receive no insecticide or fungicide. Some commonly-used orchard pesticides such as synthetic pyrethroids and EBDC fungicides kill or otherwise harm predatory mites, leading to pest mite outbreaks and need for miticide application. As discussed in previous issues of the March Message and Fruit Notes, about 90% of Massachusetts orchards harbor populations of Amblyseius fallacis. Unfortunately, populations of A. fallacis do not generally build to numbers sufficient for providing mite biocontrol until August. Studies in New York have shown that the predatory mite Typhlodromus pyri, where established, can be an extremely effective season-long biocontrol agent of pest mites, able to endure cold winter temperatures and periods of short supply of pest mites as food much better than can A. fallacis, but few Massachusetts orchards appear to harbor significant natural populations of T. pyri.

In the the Spring 1997 issue of Fruit Notes, we reported that when T. pyri were released in 1995 into blocks of apple trees in six commercial orchards in Massachusetts, they became established in all blocks in five of the six orchards. On average, after two years they had built into greater numbers in blocks managed under second-level IPM practices (no pesticide of any type used after early June) than in blocks managed under first-level IPM (sprayed with fungicide and insecticide through summer). These findings stimulated us to conduct further research on the establishment of T. pyri released in Massachusetts apple orchards.

In the 1997 field season, we released T. pyri on single trees in the center of blocks comprised of small, medium or large trees and managed under third-level IPM practices.

Releases of T. Pyri in Commercial Orchard Blocks

Our 1997 experiment was conducted in six blocks of apple trees in each of eight commercial orchards. Of the six blocks per orchard, two each contained trees on M.9, M.26 or M.7 rootstock, designated as small, medium-size or large trees. One block of each pair received first-level IPM practices, wherein growers applied insecticide and fungicide materials of their own choosing and timing of application, which extended from April through August. The other block of each pair received third-level IPM practices, wherein the intent was that no synthetic pyrethroid insecticide was to be used at any time, use of EBDC fungicides was to be minimized, no insecticide of any type was to be used after mid June, and captan or benomyl were the only fungicides to be used after mid June. T. pyri is known to be highly adversely affected by synthetic pyrethroid insecticide and also adversely affected by EBDC fungicide (when applied from bloom onward) but not by captan or benomyl. Each block was comprised of 49 trees (7 rows x 7 trees per row) of the cultivars McIntosh, Empire and Cortland. Third-level IPM is similar to second-level IPM in its focus on using biologically-based pest management practices, but it embraces integration with horticultural concerns (such as tree size) as an added component.

In May, blossom clusters harboring T. pyri were picked from an orchard at the New York State Agricultural Experiment Station at Geneva, sent by overnight mail to Massachusetts, and within three days were distributed to orchard blocks. Each third-level IPM block recieved 100 clusters, which were attached to twigs on the center tree of the block using twist ties. No T. pyri were released in first-level IPM blocks. Every 3 weeks from late July through early September in each of the 48 blocks, we sampled leaves from the center (release) tree and four trees on the perimeter of each block. The leaves were sent by overnight mail to Geneva, New York for the identification and counting of pest and predatory mites. In all, about 2600 leaves were sampled for each of the three sampling periods.

Establishment and Spread of Released T. Pyri

Throughout the season, significantly more T. pyri were present on the release tree in blocks of each tree size than on any trees at the perimeter of the blocks. In fact, extremely few or no T. pyri were found on any tree except those on which they were released. In contrast, there were no differences among tree locations within plots in numbers of A. fallacis or European red mites.

The finding that, on average, numbers of European red mites were not significantly fewer on release trees than on non-release trees on any sampling date in blocks of any tree size suggests that T. pyri were not able to build to sufficient numbers to provide biocontrol of European red mites during the three months following release. This was not a surprising result because T. pyri populations grow slowly and usually are not capable of rapidly controlling moderate to high density red mite populations. Even so, there was one block of small trees in which T. pyri were released where every tree (save one) in that block (as well as every tree in each of the other five study blocks in that orchard) was heavily bronzed as a consequence of mite injury. The only tree that was not bronzed was the center tree on which T. pyri were released.

For each sampling date, there was no significant difference among blocks of small, medium-sized and large trees in numbers of T. pyri found in third-level IPM blocks. In every case, third-level IPM blocks had significantly more T. pyri than first-level IPM blocks. For A. fallacis there were no significant differences in numbers found between first-level and third-level IPM blocks or among tree sizes for any sampling date. The same was true for European red mites.

For each release site, information on type and amount of insecticide, acaricide and fungicide used before bloom, from bloom through mid-June, and after mid-June was analyzed. Blocks of small, medium and large trees in the same orchard were treated in the same manner. With respect to insecticide, some Asana was used before bloom and some Lorsban after mid-June in first-level blocks. Both of these materials are known to be detrimental to T. pyri . The fact that they were not used in third-level blocks undoubtedly aided in establishment of T. pyri. None of the acaricides used in either first-level or third-level blocks is known to affect T. pyri substantially. As hoped, none of the third-level blocks received any Manzate, Dithane, Mancozeb or Penncozeb as fungicides, whereas first-level IPM blocks recieved substantial amounts of these materials up to mid-June. Third-level IPM blocks did, however, receive some Polyram before bloom and a small amount after bloom. Some data indicate that Polyram is just as harmful to T. pyri as the other four aforementioned EBDC fungicides, which are especially harmful when applied during or after bloom. In general, the profile of fungicides applied in third-level IPM blocks was quite (although not completely) conducive to establishment of T. pyri.

Potential for Mite Biocontrol from Introduced T. Pyri

The data presented here show convincingly that T. pyri became established on trees in which they were released: the centermost trees in third-level IPM blocks of small, medium and large trees. Growers participating in this experiment cooperated with its aims by not applying harmful insecticides or acaricides and by minimizing use of fungicides harmful to T. pyri in the blocks in which T. pyri were released. Interestingly, even more than three months after release, T. pyri failed to move even as far as four trees away downrow or crossrow, regardless of whether blocks were comprised of small, medium or large trees. We saw no evidence of suppression of European red mites by released T. pyri in any trees (except one) in which T. pyri were released. In the lone exception, a block of small trees, the foliage of the release tree remained dark green throughout summer whereas the foliage of all other trees in the block was decidedly bronzed by mid-July. For 1998 and 1999, we plan to sample the same trees sampled in each block in 1997. We expect that by 1999, T. pyri will have spread to all parts of each third-level IPM block and will have provided effective biocontrol of European red mites in such blocks, particularly in blocks of small trees.


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UPDATE OF THE FOOD QUALITY PROTECTION ACT (FQPA): WHAT'S NEXT?

In last year's March Message, we first called attention to the potential changes in registration of crop protection chemicals (especially for "minor use" registrations) that could result from passage of the Food Quality Protection Act of 1996. This legislation, which passed Congress unanimously in August of 1996, was intended to address problems caused by the outdated Delaney Amendment. At a recent USDA-sponsored meeting on FQPA in St. Louis, an EPA representative described the implications of the act with a sports analogy that "the height of the hurdle has been raised." He added that "a variety of factors have changed the way we do business" and that "it should come as no surprise that the world of OPs (41 registrations and 1,400 tolerances) is in trouble." According to the representative, the driving factor behind FQPA is "kid's risk," and that by law, EPA is no longer allowed to consider the benefits (of pesticides) in making registration decisions.

Some of the major changes in how food safety will be determined under the legislation include:

On the plus side, the act calls for expedited registration of "reduced risk" pesticides, especially those which would reduce use of older, more risky pesticides, and promotes the development and registration of "biopesticides."

Although EPA is still sorting through a number of issues (such as the 10X safety factor and whether pesticide registrants will henceforth be required to conduct in utero cancer studies), their representative at the St. Louis meeting reported that the agency has what it considers to be good data "on the hazard side." They also have information of dietary exposure, although more data are needed.

Currently, EPA has very little data on drinking water and residential exposure. In the absence of site-specific data, EPA uses very conservative models, both of which are based on a "static farm pond" source. The actual monitoring data they have available is better, but still conservative, since it tends to come from "hot spots which result in a lot of hits" (i.e. pesticide detections). Their dilemma is associated with whether an absence of data means that they should continue to use conservative assumptions, or not do so until data are called in. According to the spokesman, EPA is proceeding on a conservative track, using "default assumptions" of maximum use frequency, maximum rate and maximum allowable residue. In keeping with this conservative approach, EPA will not even use a "zero" for residues when presented with actual monitoring results, instead using "one-half of the limit of detection."

Consequently, even though non-dietary and water exposures have not been factored in, the so-called "risk cup" (meaning the total amount of pesticide a person could be exposed to every day for 70 years without additional risk) is already full for the OPs. One pesticide registrant reported that 14% of the "risk cup" was filled by chlorpyriphos alone.

So what is next? It should be pointed out that it is still somewhat early in the process, since, while EPA chose to first examine the situation with the OPs and carbamates, they will next conduct a similar review of pesticides with chronic health flags (B1 and B2 carcinogens), pesticides with other modes of action (e.g. pyrethroids) and ultimately pesticide inert ingredients.

Whatever happens, change will not be immediate, since EPA has until August of 1999 to make a finding and determine what to do. Among the options available to the agency are registration revocation, issuing "time-limited tolerances," modifying tolerances, allowing certain uses by "prescription" or doing nothing. Given the current watchdog group focus on FQPA, the last option is thought to be highly unlikely. Alternatively, Congress could push EPA to defer taking any drastic steps without reliable data on use patterns and rates and real exposure. Recently, 45 members of the House Agriculture Committee signed and sent EPA a letter suggesting that the agency is using much more conservative assumptions than Congress had ever intended. If current conservative assumptions are used, it has been estimated that under a worst-case scenario, 70-80% of OP and Carbamate uses could be canceled within the next 5 years. As Leonard Gianessi pointed out in his presentation in St. Louis, this would result in a "fundamental change" for US agriculture, given that OPs are used on over 64 million acres, and carbamates on 19 million acres. However, Gianessi pointed out also that while OP sales are estimated at $237 million annually, $128 million of this is on cotton alone, and that if 60 crop registrations were taken off the label, sales would only drop 5%. Hence, it is clear that the fate of OP and carbamate use on Massachusetts crops will ultimately depend on decisions taken by the registrants.

In the meantime, grower groups still have an opportunity to submit real-world data to EPA and USDA on regional patterns and levels of pesticide use and actual residues. The USDA expects to complete gathering data for submission later this year on actual food consumption patterns, especially of infants and children. We have also learned that a group of registrants have entered into a secrecy agreement to jointly develop aggregate risk assessment data for all of their OPs, and that this should be completed by the Fall of 1998. Some large agricultural states (e.g. California, Florida, Texas, Michigan) are actively working on data submissions for major crops. How, or if, such submissions are conducted for minor crops (given the absence of staff and money to conduct the required work) remains an unanswered question.


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SELF-GUIDED APPLE IPM TOUR

With support from an agro-environmental grant from MDFA, UMass extension produced a series of self-guided tours to explain IPM to customers at pick-your-own apple orchards. These tours were developed with guidance from cooperating growers who also contributed money for their construction. Each tour consists of eight signs that describe IPM, cultural control, biological control, monitoring, pesticide use and the biology and management of primary apple pests. Signs were constructed of plywood and Plexiglas, and mounted on pressure-treated posts. Growers added monitoring devices near appropriate signs to improve the educational experience.

A press release about the project was distributed statewide, providing an additional opportunity to explain IPM to the public. Most (not all) growers reported that the orchard tours were successful at their orchards. An apple IPM display for use at farmstands and farmers markets is under development for next year.


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PROBLEM PESTS:
1997 ACTIVITY, NEW FINDINGS AND THRESHOLDS FOR TREATMENT

 

TARNISHED PLANT BUG (TPB)

1997 Activity. In 1997, as in 1996, TPB trap captures and fruit injury were well below normal. Most growers were able to go without a prebloom spray against TPB and experienced little injury at harvest (1% or less). This is the third year in a row in Massachusetts that TPB has been below average both in trap captures and injury levels. The same has been true in other parts of New England and in Quebec. Is the cool spring weather that we have experienced during the past 3 years the responsible factor? Or are TPB parasites (Peristenus digoneutis) that were released in Mid-atlantic states, New York and New England a few years ago beginning to take hold and starting to drive down TPB populations? Or are there fewer and fewer alfalfa fields (prime sites for TPB population buildup) with the decline of dairy farming? Maybe all 3 of these factors have been involved in reducing early-season fruit-damaging TPBs. After all of this speculation getting our hopes up, we'll probably see a big year of TPB in 1998.

New Findings. Surveys in 1997 by Alan Eaton in New Hampshire showed that in some blocks, as many as 35% of TPB nymphs were parasitized by P. digoneutis, whereas none were affected by this parasitoid before inoculative releases occurred a few years ago. Good news indeed, especially if similar levels of parasitism are occuring elsewhere in New England.

Regarding insecticidal control, no new developments. The following is taken from the 1997 March Message. 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:

Cumulative TPB per trap

Type of Market

(Silvertip to Tight Cluster)

(Silvertip to Pink)

Wholesale (mainly fancy and extra fancy)

3

5

Retail

5

8

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PLUM CURCULIO (PC)

1997 Activity. In stark contrast to 1996, when PCs in Massachusetts emerged from overwintering sites early and attacked some fruit well before all petals had fallen from trees, 1997 saw a later-than-normal emergence of PCs. In fact, the weather was so cool for PC activity in 1997 that first damage scars were not seen until several days after petal fall in most parts of Massachusetts. PC damage accumulated steadily after that, with about 1/3 of the season's total PC injury occurring between the first and second PC spray, about 1/3 between the second and third spray, and about 1/3 after the third PC spray. Overall, PC damage for 1997 closed out at about 0.5% for many Massachusetts orchards, which was close to average. Because PC activity was strung out to as long as 5-6 weeks after bloom, many growers were indeed inclined to apply 3 sprays against PC. Some growers who applied only 2 sprays and stopped spraying in early June wished they hadn't because they took fruit injury as great as 2-3% during the latter 2 weeks of June. A similar pattern held true for most of the rest of New England.

New Findings. Evidence continues to build that it is the earliest blooming fruit cultivars in an orchard (be they of apricots, nectarines, peaches, plums, pear, or apples) that are most susceptible to PC damage. Does this suggest that pre-bloom sprays might help out in PC control? One might think so, but to date evidence supporting this idea is inconsistent, at least in regard to use of Guthion, Imidan or Lorsban for controlling PCs. As recently considered by Peter Jentsch of the Hudson Valley, perhaps a low-rate application of pyrethroid insecticide at mid- or late pink would provide enough punch to protect not only the earliest-blooming cultivars but also the latest-blooming ones against early-season PC. This approach is especially attractive for use in blocks containing cultivars that typically have a long bloom period (eg. Liberty) and blocks containing a mixture of early-blooming and late-blooming cultivars. Of course, the down side of using a pre-bloom pyrethroid in the very negative effect on mite predators. If there is a hot-spot block that year after year gets hit by PC because of strung-out bloom, then maybe a perimeter-row spray of Guthion or Imidan (full rate) or a spray of Asana or Pounce (1/4-1/3 rate) (for the very worst cases) would provide enough residual activity to give the entire block protection through bloom. PCs advance progressively from perimeter-row trees toward the interior of blocks, alleviating need for a whole orchard pre-bloom spray against PC.

While on the subject of perimeter-row sprays, a 1997 journal publication by Charles Vincent and colleagues in Quebec confirmed their earlier findings and our own experience in Massachusetts that perimeter sprays are equal to whole-block sprays against PC so long as PC populations are low or moderate in size. For Quebec orchards, a perimeter is considered to be the first 5 rows or first 20 yards of a block.

Maybe we at UMass are too cautious, but we are not yet ready to recommend doing away with all whole-orchard sprays against PC and going with only perimeter-row sprays until we have an effective trap for monitoring PC abundance. See above discussion in section on "General Topics and Opinions" for current progress on developing a PC monitoring trap. For the time being, we will continue to recommend at least one (or two) whole-orchard sprays against PC, especially where sawfly in a regular problem.

In regard to types of insecticides effective against PC, 1997 tests by Harvey Reissig in western New York showed that 3 whole-block treatments of Guthion gave about 92% protection against a large population of PCs, with about 72% protection by Lorsban, 71% by Diazinon and 53% by Provado. So Guthion (or its close cousin Imidan) remain as our standard against PC. As mentioned in the 1997 March Message, the residual activity of Sevin against PC is so short (3-4 days) that one shouldn't count on it to provide much more than a quick knockdown to be followed soon by (if not combined with) Guthion or Imidan.


Thresholds for Treatment. No change here from 1997 recommendations. The best guide to determining when to start spraying for PC is to examine fruit as high as can be reached on early-blooming trees of perimeter rows (or on newly unsprayed trees) in traditional hot spots and spray as soon as you see a fresh egglaying scar. Don't wait until fruit begins to size up before spraying. PC can damage a fruitlet as soon as the petals fall from it. When to stop spraying against PC? Consider using the day degree (DD) model of Reissig and Nyrop developed for New York. Calculate the numbers of DD above 50F (as a base) beginning at petal fall. The timing for the last spray should be such that an active insecticide cover is in place until 340 DD are accumulated. Day degrees for a single day are calculated by subtracting 50F from the average temperature for that day (that is, the average of the maximum and minimum).

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APPLE MAGGOT (AMF)

1997 Activity. As in 1996, AMF captures on red sphere monitoring traps and AMF injury to fruit at harvest were below normal. This was true in Massachusetts and most other New England states. AMF pupae overwinter in the soil and require rainfall to stimulate adult emergence. Very dry soil in June and July was not conducive to emergence, but emergence did get underway in earnest in August. Peak AMF populations in commercial orchards occurred from mid-August to mid-September in Massachusetts.

New Findings. A journal article by Trimble and Solymar in Ontario showed that 3-4 perimeter-row sprays of Imidan were equivalent to 3-4 full-orchard sprays of Imidan in providing AMF control in both years of testing. We found the same to be true in Massachusetts during extensive tests of perimeter-row sprays against AMF from 1986-1994. So this is a viable option for AMF control provided that there is no within-orchard emergence of AMF from fallen fruit of the previous year (early-ripening cultivars are especially prone to AMF larvae completing development before frost and giving rise to within-orchard emergence).

Reissig evaluated different insecticides against AMF in New York in 1997 and found that 3 treatments of Guthion reduced damage by a large AMF population by 100% compared with 72% reduction in damage by Lorsban and 0% reduction by Diazinon or Provado.

Progress on development of pesticide-treated spheres for controlling AMF is given above in the section "General IPM Topics and Opinions."

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 in early July. Continue monitoring in late-ripening cultivars through September.

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LEAFMINERS (LM)

1997 Activity. In contrast to the fairly quiet LM year of 1996, the year 1997 saw large (even huge) populations of LM in many (perhaps most) orchards of Massachusetts and other southern New England states. Interestingly, LM were pretty much at normal levels in northern New England and Quebec. To give but one example, in one 10-acre block of apple trees in a Massachusetts commercial orchard, an average of 1040 LM adults per trap was captured by bloom on the 8 sticky red rectangle traps stapled to tree trunks, with at least 2400 LM captured on a single trap - a new record for a Massachusetts orchard. In response to the high trap captures, most Massachusetts growers opted to apply insecticide against first-generation LM using either Provado or Agrimek. Since 1995, Provado has been labeled for use against LM. Observations since then suggest that Provado usually, though not always, holds down LM for the year in which applied and for the following year. But by the second year after application, if 1997 is any indication, populations built to damaging levels again. Precise reasons for this apparent trend are unknown. It could simply be a case of the ability of LM to multiply so fast (5-10 fold) from one generation to the next. By the time of the 5th generation after initial application (i.e. first LM generation of 1997 if Provado was applied against the first LM generation of 1995), populations have rebounded to high levels. Another reason could involve suppression of parasitism by use of Provado, although we have no direct evidence for this as yet.

Besides apple blotch leafminer (ABLM) and spotted tentiform leafminer (STLM), some Massachusetts orchards experienced very high levels of the apple leafminer, Lyonetia speculella (ALM) in 1997. In an orchard not treated against ALM in 1997, this species caused widespread damage to terminal growth and watersprouts (more about the life history and damage potential of this species below).

New findings. In 1997, Connor and Taverner published an interesting journal article on the evolution and adaptive significance of the leaf-mining habit of several kinds of leafmining insects. Advantages to larvae of spending their entire lives sandwiched between upper and lower surfaces of leaves were concluded to be: lower incidence of disease infection; a micro-environment with lower evaporative demand and therefore protection from desiccation; protection from effects of UV radiation; and avoidance of certain plant defenses, resulting in higher feeding efficiencies. Disadvantages were concluded to be: lower mobility and consequent higher mortality from parasitoids; higher mortality associated with premature leaf drop; and smaller than average body size. It would seem, therefore, that by the very nature of the evolutionary pathway leafminers have taken, they are particularly prone to attack by parasitoids. We should take advantage of this inherent "weakness" that lends itself so well to biocontrol by parasitoids.

In regard to apple leafminers (ALM), the following is condensed from remarks of Dick Straub of the Hudson Valley in the July 7, 1997 issue of "Scaffolds." Unlike the mines of STLM and ABLM, which have a stippled appearance, mines of the ALM appear as brown blotches. Also, ALM constantly expels frass (excrement) on a silken thread from the mine, which ABLM and STLM do not do. Finally, just before pupating, ALM larvae spin cocoons which are suspended by threads and resemble a hammock. ALM has 4-6 generations a year in the Hudson Valley, whereas ABLM and STLM have only 3 per year. Of particular importance is the fact that larval damage of ALM is confined to the youngest foliage, especially terminal leaves of vigorously growing shoots and watersprouts. Severely damaged leaves tend to drop off prematurely, thereby decreasing the number of the most photosynthetically capable leaves. Potential for economic injury is greatest in young blocks, which can ill afford to suffer reduced photosynthesis. Infestations of ALM are most apparent toward harvest. Fortunately, such infestations are not known to cause premature fruit drop. ALM do not seem to be controlled by organophosphate insecticides, but apparently are susceptible to the same materials effective against ABLM and STLM. Sprays against ALM may be needed only on non-bearing trees where vigor is essential or on bearing trees that had high infestations the previous season.

Many growers have now switched from using Vydate, Lannate, or a synthetic pyrethroid insecticide against LM to using Provado or Agri-Mek. Also, another new material (Spinosad) may be labeled for use on LM in 1998. How do these new materials compare with one another in effectiveness? In 1997, Glen Morin and Robin Spitko of New England Fruit Consultants (NEFCON) made such comparisons, with these results. When applied shortly after petal fall, Provado gave slightly better control than did Spinosad against first-generation LM. Spinosad does not have systemic (trans-laminar) activity but this may not have been the reason underlying its slightly less effectiveness. In a separate test, NEFCON compared Provado with Agri-Mek (plus oil), each applied at petal fall. Agri-Mek gave better LM control, with control effects lasting at least through second-generation LM. Finally, Larry Hull in Pennsylvania compared a pink with a petal fall application of Agrimek and found the petal fall application to be about 20 times more effective against LM. From this information, it seems that Agri-Mek at petal fall may be the superior choice among these 3 materials. More comparative information is needed, however, and regardless of which material is best against LM, alternation of materials from year to year is advisable to delay resistance. Also, we need to know more about effects of each of these materials against parasitoids and other beneficials.

In 1997, both NEFCON and Hull compared various adjuvants for use in combination with Agri-Mek at petal fall. NEFCON found Sunspray Ultrafine Oil (UFO) and HM 8902 to be equally effective as adjuvants and more effective than Regulaid or LI-700, which were about equal to each other. Hull found Sunspray UFO to be more effective than Sylgard 309, SilWet L-77, Regulaid or LI-700 when considering effects lasting through the second-generation of LM. So it seems that the best material to add to Agri-Mek might be Sunspray UFO for maximizing effects against LM. However, use of oil with Agri-Mek could pose a problem if captan were to be applied as fungicide.

Thresholds for Treatment. Our thresholds are the same as given in the 1996 and 1997 March Message, with the caution that trap capture thresholds apply to ABLM and less so to STLM and that they may be unreliable if fewer than 4 traps are used per 8-acre block. For Massachusetts, we suggest the following:

Cultivar

Cumulative ABLM per trap

Silvertip to Tight Cluster

Silvertip to Pink

McIntosh

4

9

Non-McIntosh

8

21

Cumulative first-generation sap mines per 100 leaves

McIntosh

7

Non-McIntosh

14

Cumulative second-generation mines per 100 leaves*

McIntosh

50

Non-McIntosh

100
* In a year of above-average rainfall, these thresholds for second-generation mines could be doubled.

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MITES

1997 Activity. The cool weather that prevailed through early June held down the growth of mite populations until mid-or late June. The 6-week warm to hot dry period from mid-June through late July was ideal for rapid mite population growth. The cooler, damper weather of August combined with predator buildup to put a lid on mite buildup, and populations declined to low levels by the end of August. In Massachusetts and several other states in the Northeast, two-spotted mites as well as rust mites were present in considerably higher than normal (possibly even damaging) numbers in some orchards. Was it the dry weather during July that led to these higher numbers, or was it a consequence of use of a new array of insecticides and acaricides? We can only speculate and hope that there will not be a repeat in 1998.

New Findings. Biocontrol by predators: The most important factor in maintaining pest mites below damaging levels is presence of sufficient predatory mites to promote effective biocontrol. Unsprayed apple trees rarely, if ever, experience problems with pest mites. The main reason: presence of a complex of predators that achieve biocontrol. We get into trouble in commercial orchards when we use insecticides, fungicides or miticides that disrupt predators, either by killing predators outright or adversely affecting some aspect of predator physiology, such as ability to reproduce.

Jan Nyrop of Geneva, New York has been studying mite predator biology and dynamics for several years now. Here are some of his conclusions, based on findings through 1997.

The predator Amblyseius fallacis, although present in most Northeast orchards, is rarely found in sufficient abundance in apple trees to provide mite biocontrol before mid or late July. The main reasons: (1) high susceptibility to cold winter temperatures that knock back overwintering populations to low levels; and (2) need of substantial motile pest mites as prey in April and May, absence of which causes A. fallacis to migrate away from apple trees. Because European red mites are still in the egg stage at this time, A. fallacis have little reason to hang around. So they emigrate and don't return until July. They have the capacity to eat a lot of pest mites and thus can do a good job of bringing down a large population of pest mites in August, provided they are not killed off by pesticides.

The predator Typhlodromus pyri can be found on apple trees throughout the year. It can withstand low winter temperatures better than A. fallacis and it can survive well on fungal spores in the absence of motile pest mites in April and May. In fact, Nyrop is now working on application of fungal spores to apple trees in spring to see if he can enhance more rapid buildup of T. pyri in spring. If T. pyri are not undone by adverse pesticides, Nyrop has shown conclusively that they, by themselves, can provide excellent mite biocontrol year after year beginning in May and lasting through the entire summer.

In 1996, Nyrop initiated and coordinated a project involving the release of T. pyri in several orchards in each New England state and in New York. The released T. pyri were all taken from a population in New York that (according to Nyrop's latest thinking) is more resistant to certain orchard pesticides (such as organophosphate insecticides) than are populations native to the areas in which they were released. Data taken in 1997 on the fate of 1996 released T. pyri have shown solid establishment in 36 of the 40 orchards in which they were released. T. pyri spreads slowly from tree to tree. Hence, leaf samples taken in 1997 were confined to the 6 trees per orchard on which releases occurred in 1996. These samples showed that for the release trees, T. pyri were able to maintain red mites below 5 per leaf throughout 1997 in all 36 orchards. In contrast, red mites exceeded 5 per leaf in control (non-release) plots in 10 of the orchards. T. pyri populations per leaf more than doubled from 1996 to 1997. This is good news indeed.

In Massachusetts (in cooperation with Nyrop), we began a study in 1997 of the rate of establishment and rate of spread of T. pyri released in 8 blocks each of M.9, M.26 and M.7 trees in May. Results (given above in more detail in the "General Topics" section) are very encouraging in regard to establishment, which occurred in all 24 blocks. We will be tracking rate of spread of T. pyri in blocks of each tree size in 1998 and 1999.

Undoubtedly the major stumbling block to establishment and spread of released T. pyri is use of pesticides having adverse effects. The following represents a compilation of 1997 information on adverse effects taken from Nyrop in New York, Mike Hardman in Nova Scotia, Noubar Bostanian in Quebec and Howard Thistlewood in Ontario. Synthetic pyrethroid insecticides have powerful adverse effects. The only exception might be use of a very low rate (one-tenth normal rate) or an encapsulated form of pyrethroid in a single pre-bloom application. EBDC fungicides such as mancozeb and polyram, as well as the fungicides dodine and ziram, also have powerful negative effects. They prevent hatch of T. pyri eggs. Because T. pyri lay few eggs before bloom, it seems that it is safe to use EBDC fungicides, dodine and ziram before bloom. But their use from bloom onward can be devastating to T. pyri, especially for mancozeb. These fungicides apparently do not kill T. pyri adults or nymphs, but are very detrimental to the eggs. Among miticides, neither Agri-Mek, Savey or Apollo are known to have any substantial negative effects on T. pyri. But Pyramite at a high dose have a negative effect, although a low dose seems to be OK. Organophosphate insecticides (except Dimethoate and Lorsban) and Sevin have minimal effects on released T. pyri, but Vydate, Lannate, and Carzol are harmful.

Control by miticides. By June of 1997, 4 new miticides had been registered since 1995 for use on apples: Apollo; Savey; Agri-Mek; and Pyramite. The first 3 in this group are intended for use just before or just after bloom, whereas Pyramite is intended as a rescue material for use in July or August. In the 1997 March Message, we presented an extended discussion of possible tactics for employing these materials. We will not repeat such discussion here. Rather, we focus on 1997 results from trials comparing these materials conducted by NEFCON in Massachusetts, Art Agnello and Harvey Reissig in New York, Larry Hull in Pennsylvania, Henry Hogmire in West Virginia, and Jim Walgenbach in North Carolina.

In regard to the miticides themselves, studies in New York showed that Apollo applied at petal fall performed considerably better (i.e. provided season-long mite control) than Apollo applied at tight cluster or at pink. This supports results of other studies reported last year. Unfortunately, it's not legal to apply Apollo after tight cluster. Savey at tight cluster gave mite control equivalent to Apollo at pink and to Apollo plus oil at tight cluster. The bottom line is that Apollo (1-2 oz/100) plus oil (1 gal/100) at tight cluster is about equal to Savey (1 oz/100) at tight cluster or pink in providing good to excellent mite control. In both West Virginia and New York, Apollo at tight cluster without oil failed to give season-long mite control, with plots requiring Pyramite by mid-July. In Pennsylvania, Agri-Mek plus oil applied at pink gave slightly better mite control than Agri-Mek plus oil applied at petal fall. The petal fall timing was much better than the pink timing against leafminers, however. In New York, Pyramite applied at petal fall gave much better red mite control than when applied at pink. In North Carolina, late-June applications of Pyramite, Vendex or Kelthane at recommended rates reduced red mites over the next 5 weeks by about 90, 80 and 60%, respectively, and reduced rust mites by about 70, 70 and 50%, respectively. One general observation is that control of two-spotted mites requires a higher rate of Pyramite than control of red mites. Unfortunately, no 1997 study of which we are aware directly compared 2 pre-bloom oil sprays with Agri-Mek, Apollo, Savey or Pyramite.

Agri-Mek must be accompanied by an adjuvant (such as oil) to facilitate its activity. Several adjuvants were compared in Massachusetts, New York and Pennsylvania in 1997. Among horticultural oil (such as Sunspray Ultrafine Oil), Sylgard 309, SilWet L-77, Regulaid and LI-700, no adjuvant proved better than oil. Silwet was a close second, with the others close behind. Oil is inexpensive but does pose potential phytotoxicity problems if captan is to be used in place of EBDC fungicides after bloom.

In 1997, some growers tried Silwet alone for mite control. In some cases, it provided immediate knockdown of motile stages of pest mites, much the same way that soapy water does. But it appeared to have little or no residual effect. Thus, mites hatching a day or more after application were not controlled.

Cyhexatin (formerly sold as Plictran) may be resurfacing under a new name (Pennstyl) and may receive a label for use on apples, but we do not expect that this labeling will occur until after the 1998 field season. Addition of such a chemical could be very good news for apple growers, especially those who do not have populations of red mites that were formerly (and still could be) resistant to cyhexatin.

As a final note, virtually all investigators who have worked on control of mites on apples would place highest priority on biological control of mites via predators as the best long-term solution to mite management. Many growers who have constructed their pesticide-choice programs so as to maximize the potential for mite predator buildup find they no longer need to use any miticide except for pre-bloom oil sprays. If it appears from early-season sampling or from previous years' experience that some miticide in addition to pre-bloom oil will be needed, then combined 1996 and 1997 information suggests that Apollo plus oil at tight cluster, Savey with or without oil at tight cluster or pink, and Agri-Mek with oil (or some other adjuvant) at petal fall or a week after petal fall are the choices that will provide best mite control with least adverse effects on predators. Pyramite ought to be considered only as a rescue material for use in late June, July or August. As strongly emphasized by Art Agnello of New York, growers should do everything in their power to reduce the likelihood of resistance to these new materials. Resistance has been shown to occur in some orchards after only 3 consecutive years of using Apollo or Savey (reports from other continents) and after only 4 consecutive years of using Pyramite (reports from Asia). Apollo and Savey are very similar in their mode of action. If a grower plans to use early-season miticides in a preventative-type program, then as suggested by Art Agnello, year 1 could involve Apollo or Savey, year 2 Agri-Mek, year 3 Apollo or Savey, year 4 Agri-Mek and so on.

Thresholds for Treatment. As pointed out by Art Agnello of New York, the miticides we used to use (for example, Omite and Plictran) were usually applied in response to a threshold population detected by timely sampling. Thus, thresholds were very useful for determining need for application. In contrast, Apollo and Savey must be used so early in the season that it is simply not possible to determine beforehand whether a given orchard will ultimately need intervention against mites. This shift away from a scouting-based (responsive) to a calendar-based (preventative) management approach does not bode well for implementation of good IPM practice. In addition, such a preventative approach is almost certain to lead to early development of resistance. Apollo and Savey were originally intended for use as rescue materials in summer and work well for this purpose. Concern with residue on fruit has constrained their use to pre-bloom, thereby defeating their employment within a traditional IPM approach.

What to do? We have no answer, except to continue to offer up thresholds developed in New York and intended for decisions on application of materials beginning at petal fall, which would involve potential use of Agri-Mek, Vendex, Kelthane, Pyramite and perhaps in the near future, Pennstyl.

Time Frame

Action threshold based on % leaves with motile mites

May 15 - June 1*

30%

June 1 - June 15*

45%

June 15 - July 1*

55%

July 1 - July 15**

65%

July 15 - August 15**

80%
*Take middle-age fruit cluster leaves
**Take middle-age leaves from anywhere

PEAR PSYLLA

1997 Activity. Prebloom oil programs, coupled with some solid options for treatment after petal fall led to good control of pear psylla through mid-July. Few growers found it necessary to use a late-season treatment of either Provado or Pyramite.

New Findings. Applications of Agrimek or Mitac 10-15 days after petal fall held psylla populations well in check this year. Provado, which was recently labeled for use on pears, has shown good knockdown ability when high populations of nymphs are present, but residual control is limited to about 10 days. Thus it is best suited as a late-season treatment. Some growers used a full label rate of Pyramite against late-season buildup, but found no significant reduction in psylla populations.

While chemicals currently available for control of pear psylla are performing well, studies were done in Washington State aimed at determining the effects of non-traditional control chemicals on feeding and egglaying of first- and second-generation psylla adults. Results indicated that use of oil, particularly prebloom treatments, significantly reduced the ability of psylla to feed or oviposit. Such findings further emphasize the importance of early season oil treatments in reducing the potential for late season problems.

Thresholds for Treatment. A second study was done in Washington State to determine if there was a relationship between numbers of psylla adults captured on sticky panel traps and real canopy populations, measured by limb tapping. In short, this study found no link between sticky trap captures and the canopy population. Because of the lack of an effective trap for monitoring buildup of pear psylla, inspection of terminals remains the most effective monitoring practice. A treatment of Mitac or Agrimek 10-15 days after petal fall is recommended if 6-10% of terminals are infested.

PEACH PESTS

1997 Activity. Injury to peaches by plant bugs and stink bugs was relatively light in 1997. In most orchards, regular sprays directed at plum curculio coupled with effective ground cover management were enough to keep these catfacing insects at bay. However, management of last year's peach crop was not challenge-free, as heavy infestations of peachtree borer were observed in several orchards. Infestations of peachtree borer and lesser peachtree borer often increase the severity of Cytospora canker infections, resulting in increases in the amount of gum exuded from the trunk and scaffolds of infested trees. Peachtree borer generally works at or below the ground surface, while lesser peachtree borer prefers to work beneath mouse guards or vegetation that has grown up around the trunk. Presence of either species is evidenced by frass (resembling pelletized sawdust) exuding from the trunk, often in association with Cytospora gum. In several cases last season, these borers were able to girdle tree stems, killing young to middle-aged trees in late June and early July.

New Findings. Recent studies in New Jersey focusing on tarnished plant bug activity emphasize control strategies for catfacing insects reported in last year's March Message. A critical step in keeping the pest population below damaging levels is rapt attention to groundcover management. Understory plants such as clover and broadleaf weeds are well known to harbor large populations of plant bugs, while tightly cropped, dense grasses discourage pests from taking up residence in the groundcover.

Approaches to Treatment. For control of plant bugs on peaches, shuck fall is the time to pay particularly close attention to signs of attack, as feeding peaks between shuck fall and 1/2" to 3/4" fruit. Research has shown that either Guthion or Imidan alone are at best 50% effective in preventing plant bug injury. Therefore, we recommend use of a full rate of Guthion or Imidan in conjunction with a 1/3 labeled rate of a pyrethroid such as Asana, Ambush or Pounce. We feel that because of the tendency of pyrethroids toward high absorption into and slow release out of the bark of the trees, the 1/3 rate of pyrethroid offers a good compromise, extending the residual effects of the chemical while limiting the destructive effects against mite predators. If mowing is planned in blocks of peaches, it is important that an active protective insecticide cover be in place at the time of the mowing. This will limit the feeding activity of plant bugs, which are numerous in the groundcover, when they are pushed into the canopies by mowing.

If signs of borer activity are seen early in the season, then a trunk/scaffold treatment may be in order shortly after petal fall. For peaches, we recommend Lorsban, although Thiodan can be effective if the weather is particularly warm (85 degrees or more). For such an application, particularly if borers are active near the base of the trunk, grass and duff should be pulled away, allowing the chemical to reach the pests.

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IPM MANUALS, SUPPLIES AND SERVICES

PURCHASE OF 1998 PEST CONTROL GUIDES, IPM MANUALS, ETC.

For 1998, the monthly newsletters; weekly Healthy Fruit messages; the March Message; the Peach, Pear and Plum Guide; and the 1998 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 the 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 to 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:


The 1998-1999 New England Apple Pest Management Guide will be mailed to all who subscribe to the $40 package of information. This edition of the NEAPMG was edited by Glen Koehler, Lorraine Los, Dan Cooley, Jim Dill, Bill Lord and Jim Schupp. An electonic copy, and other resources, are available at the Virtual Orchard.


There will be a new version of the Peach, Pear and Plum Guide for the 1998-1999 growing seasons, which will include updated pest biologies and control methods. The Peach, Pear and Plum Guide is edited by the UMass Tree Fruit Team.

Tree fruit management guides should only be used during the growing season(s) for which they were written. Information obtained from old guides may be outdated 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 management 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:

1998-1999 New England Apple Pest Management Guide

$15.00

1998-1999 Peach, Pear and Plum Guide

$**

Opportunities for Increased Use of Biological Control in Massachusetts

ID Code: EXPF 0900 0718

$7.00

Biological Control Fact Sheets:

Apple Blotch Leafminer

ID Code: IPMA 000L 594A

$2.95

Spider Mites in Apples

ID Code: IPMA 000L 595A

$2.95

** The 1998-1999 Peach, Pear and Plum guide will not be in print until April 1998.


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 the Bulletin Center, Draper Hall, University of Massachusetts, Amherst, MA 01003. Please use the ID code (if provided) to specify the publication you are ordering.


Fruit Notes, a quarterly journal published by the UMass Plant and Soil Sciences Department and UMass Extension, contains important new research findings on fruit growing in Massachusetts. The subscription price is $10.00 per year ($12 US funds for foreign subscriptions), and checks should be made out to the University of Massachusetts and sent to Wesley Autio, Department of Plant and Soil Sciences, Bowditch Hall, University of Massachusetts, Amherst, MA 01003.


Tree Fruit Production Guide 1998-1999. 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:

The New York Fact Sheet series features excellent photographs, and a set of 30 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. The on-line versions are available at http://www.nysaes.cornell.edu/ipmnet/ny/fruits/FruitFS/index.html. The general listing of Extension publications from Geneva is available at http://www.nysaes.cornell.edu/pubs/.


"Pest Management Fact Sheets" Cooperative Extension Service, University of New Hampshire, Durham, NH 03824. Free of charge. Fact sheets are available on:

On the web, contact UNH at http://ceinfo.unh.edu/entopubs.htm.

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 Michgan State University. Contains many excellent color pictures and straightforward information on most pests encountered in the field. Available in hardcover ($37.50) or laminated ($30.00) from: Bulletin Office-TFP, Michigan State University, 10B Agricultural Hall, East Lansing, MI 48824-1034. The publication number is NCR-63 (Common Tree Fruit Pests). Checks should be made out to Michigan State University. Other Michigan State Bulletins are listed at their web site, http://www.msue.msu.edu/msue/imp/