Summer Edition 2001 #9
Vol. 13, No. 14
July 26, 2001
Crop Conditions and Pest Summary
Strawberry fields are regrowing following renovation. Irrigation is important
at this time. Don't let those fields dry out. Leaf tissue analysis should
be done once there are fully mature new leaves on the plants. See more
on this below. Some fields continue to have feeding damage from root weevils.
Also keep an eye out for shot-hole feeding injury from straw-berry root
worm beetles. Highbush Blueberries harvest is in full swing. Yield is
variable. Continue to watch for Blue-berry Maggot Fly. Also, I have seen
a fair amount of Anthracnose fruit rot this year. This is often a postharvest
problem and one that is more often found on late season varieties like
Coville. Alternaria can also be a problem now. Also, see the Blueberry
Section below for information on Blueberry Scorch which has now been found
at two locations in Massa-chusetts. Summer raspberry harvest is continuing.
Yields appear to be fair to moderate. As mentioned in earlier issues of
Berry Notes, winter damage was high on many summer raspberry fields. New
cane growth is terrific, however. Primo-canes in some fields are twice
as long as the floricanes. Mites (both two-spotted spider mites and European
red mites) are flaring up in some locations. Predator releases will help
suppress them without the need for sprays during harvest. Call me for
sources (413-545-4347). Fall raspberries are coming along well. Regular
precipitation has benefited them and pro-duced strong cane growth. Early
varieties already have some green fruit in some locations. Some growers
have sprayed for potato leafhopper. This can still be a problem, so keep
checking your fields for 'hopper burn'. Grapes clusters are sizing up.
Reports indicate a very good crop, with good quality so far. Berry moth
is still a factor. Be sure to check traps or use mating disruption ties.
Also keep an eye out for Grape mealybug and European red mites. Mealybugs
are found be-tween layers of bark on the trunks, especially near spurs.
Mites reside on the underside of the leaves and often require a hand lens
in order to see them. Disease management programs should continue on a
post bloom schedule. Good coverage before bunch closing will help with
incipient infections and reduce bunch rot later on. Moving catch wires,
shoot thinning and leaf pulling are common activities now.
Strawberry Update - Sonia Schloemann, UMass Extension
Fertilization: You will be fertilizing your bearing fields with 25-60
lbs. N/acre as part of the renovation process, but new plantings will
benefit from a fertilizer applica-tion now, too. 30 lbs of actual N per
acre is the amount to apply. Use whatever form is cheapest. 200 lbs of
15-15-15 is one possibility, but 90 lbs of ammonium nitrate is fine if
you applied P and K at planting. Keep applying N at monthly intervals
until you've put on a total of about 100 lbs of actual N.
Leaf Tissue Sampling: Leaf tissue analysis is a way of determining the
actual nutritional status of plants. It is an excellent and inexpensive
way of finding out if your fertilization program is working or if changes
need to be made. The analysis provides information on foliar N, P, K,
Ca, Mg, Mn, Fe, Cu, B and Zn levels for the leaves sampled and recommendations
for corrective measures if needed. Combined with soil testing, leaf tissue
analysis can help pinpoint the source of problems and determine what measures
may be needed to ensure proper nutrition of the crop. For strawberries
sample from the first fully expanded new leaves after renovation.
Collect 30 - 50 leaves per sample. Sample different va-rieties separately,
if possible. Collect leaves from as many plants as possible in the sample
area. Remove the petioles (leaf stems) from the leaves. Gently wash the
leaves in tap water to rinse off soil or spray residue. Al-low the leaves
to air dry until they are brittle before plac-ing into a paper bag. The
cost per sample is $15. A check made out to the University of Massachusetts
must be sent in with the sample. Send sample(s) to the Soil and Plant
Tissue Testing Lab, West Experiment Station, Box 38020 UMass, Amherst,
MA 01003 or call (413) 545-4768. Test results will be accompanied with
recommendations.
Potato leafhopper: Check new plantings now for potato leafhopper (Empoasca
fabae) damage. Leafhoppers feed primarily on the underside of strawberry
leaves, causing them to yellow between the veins and become curled and
distorted. Feeding activity is most serious during the late spring and
early summer. Leafhoppers are 1/8 inch long, green, bullet-shaped insects
that take flight quickly if disturbed.
The nymphs are light green and do not fly. Nymphs are easily identified
by their habit of moving sideways when disturbed. Insecticides should
be applied only when large populations of nymphs are noted on the leaves
or symptoms become apparent.
Highbush Blueberry
NOTICE TO BLUEBERRY GROWERS: The presence of the Blueberry Scorch
virus (aka Sheep Pen Hill Disease) has been confirmed at two locations
in Massachusetts, one in Barnstable County and one in Berkshire County.
It is likely, given the distance between these two locations, that we
have this virus in other locations, as well. It is very important to note
the symptoms decsribed below in order to determine if you may have this
virus at your farm. It is also very important to determine if you have
aphids feeding on your bushes, since they are the vectors that will transmit
the virus from one plant to another. Growers should take some time now
to inspect their blueberry plants for aphids by looking at the underside
of the leaves on newer growth. If you notice aphids on your plants, especially
if you also have noticed a blossom blight/twig blight condition selectively
on 'Berkeley', 'Weymouth', 'Pemperton' or 'Dixi'. 'Blueray' appears to
exhibit different symptoms where just a dramatic leaf yellowing is found.
'Bluecrop' may not exhibit very noticeable symptoms, but may suffer lower
yeilds. Look at picutures of scorch in the NRAES Blueberry Production
Guide or in the Blueberry Disease Compendium. For readers with Internet
access, Washington State University has a very good fact sheet on Blueberry
Scorch. It can be found at http://www.geocities.com/martinrr_97330/BlSVweb/Pestalert.htm.
Please call me (413-545-4347) if you suspect that you may have this disease
in your blueberries. We are developing a protocol for systematically sampling
the state next summer, and will need the help of growers and private consultants.
Please note that I will be out of the office the week of July 29 to August
5. See more about this disease from New Jersey below.
Blueberry Scorch Virus - Peter Oudemans, Rutgers University
Blueberry scorch is a virus disease that is increasing greatly in frequency
in New Jersey. The pathogen causes flowers to die without being fertilized
and can re-sult in major crop losses. In Burlington and Atlantic counties
fields with 70-90% of the plants infected have been observed. Thus this
disease represents a serious threat to the blueberry industry.
Growers and scouts should watch for development of scorch at this time
and flag all suspect bushes. Symptoms (see below) are easily seen during
bloom. Growers should be aware if this disease is present on the farm
and where the infected bushes are located. Mark locations of the disease
on a farm map and monitor these areas next year. When suspect bushes are
found they should cut back and removed. Aphid scouting and management
should be made high priority in fields with infected plants.
Symptoms of the disease vary depending on the cultivar. In "Weymouth"
the classic symptoms of scorched blos-soms and a Phomopsis-like die-back
are commonly seen. In other cultivars such as "Duke" and "Bluecrop"
the blossom scorch is less common and fruit may appear to set but will
not develop. The plants may also appear chlorotic (yellowing similar to
nitrogen deficiency) and partially defoliate. The disease may be easier
to see by standing back from the bushes rather than close inspec-tion.
Shortly after the bloom period is over plants will begin to recover. Even
though symptom expression may not occur every year, infected bushes remain
a source of inoculum in the field increasing the possibility for dis-ease
spread. Significant yield loss is always
A virus causes blueberry scorch. Viruses are among the smallest pathogens
of plants. They cannot be cultured like bacteria and fungi and are too
small to be seen through a light microscope. They are usually detected
using antibodies used in kits that give a color reaction. Diagnosis by
symptoms is the fastest method but often needs to be verified through
a diagnostic kit. For viruses to infect a plant they must enter a living
plant cell through a wound. In the case of Blueberry Scorch, aphids can
carry the virus on the sucking mouthparts or the stylus and inject the
virus into the cell while feeding on plant sap. Once inside the cell the
virus begins to multiply and spread to other cells in the plant. Eventu-ally,
the entire plant becomes infected and develops symptoms. Once a plant
is infected it does not recover. Although infected plants may appear healthy
during some years the infection is persistent and will greatly reduce
berry production over the long term. Furthermore, the infected plants
represent a source of inoculum that can be transmitted to healthy plants.
For these reasons, it is a very good practice to remove infected plants.
Transmission of the virus is most likely by aphids. Al-though no experiments
have been conducted to prove this directly, transmission by of the virus
by aphids to other plants from infected blueberries has been accom-plished.
In addition, transmission of other similar vi-ruses is also accomplished
through aphid transmission. In addition, plant virologists have been unable
to trans-mit the virus between blueberry plants using infected plant sap.
This suggests that mechanical transmission by pickers, pruners, or harvesters
is also unlikely. Another very important point regarding transmission
is the role played by infected cuttings. For example, since mother plants
are often not allowed to flower they probably do not show symptoms. If
cuttings are used from these in-fected plants it is likely that the resulting
transplants will also be infected. This is an excellent way to introduce
scorch into a field. Therefore, testing mother plants for viruses is an
excellent sanitary practice that will have major beneficial effects on
the establishment of new fields. Testing kits are currently available
for the eastern strain of the virus. (Source: Blueberry Bulletin, Vol.
17, No. 4, May 3, 2001)
Disease Update from New Jersey - Gary C. Pavlis, Rutgers University
Anthracnose: Farm visits this week have shown that the hot, muggy, rainy
weather has increased the incidence of anthracnose. Spores are produced
during wet periods and are distributed to susceptible tissues by splashing
rain. It has been suggested that at least 12 hours of continual wetness
is required at temperatures of 59o to 85o F in or-der for these spores
to germinate and cause infection. The vast numbers of spores in each fruit
are spread to other fruit, again by rain or after harvest when one fruit
touches another. The fruit will then soften, pucker and exhibit some salmon-colored
sporulation. The only fun-gicides that are of use to us now are Captan
and Aliette. Dr. Peter Oudemans has suggested that if anthracnose is a
concern, it would be more effective to spray Captan before a predicted
rain then after because it is preventive in nature and cannot burn the
infection back once it has started after a rainy period.
Alternaria: Alternaria fruit rot is being seen in some fields. Those
using Captan in their sprays at this time may see some control. If you
are seeing a leaky, watery fruit rot with a dark green moldy growth on
the blossom end, that's Alternaria. The berries just seem to get soft
and leaky and of course are not attractive. This fungus overwinters on
twigs and in debris on the ground. Infec-tion occurs mainly after the
fruit begins to ripen. Overripe or injured berries are particularly susceptible
to decay. Wet or humid conditions favor growth of the fun-gus. (Source:
Blueberry Bulletin, vol. 17, No. 14, July 20, 2001)
Brambles
Raspberry Update from Ontario - Pam Fisher, OMAFRA
Harvest of raspberries continues and is winding down in the earliest
areas. A few growers have noticed a white, powdery appearance on Boyne
raspberries. This is not likely to be powdery mildew but is probably the
natural waxy bloom which develops on Boyne in response to hot dry weather.
Verticillium wilt can affect raspberries and I have seen two cases of
this problem in recent weeks. Affected raspberry plants will wilt and
dry up. The problem re-sembles Phytophthora root rot in some cases, both
pri-mocanes and fruiting canes can be affected. Black rasp-berries are
especially susceptible to verticillium wilt. In black raspberries, the
problem is easy to identify because the affected canes develop a very
blue colour along the stem. There is no control for this disease, although
soil fumigation before planting may help. Do not plant raspberries back
into affected areas for 3-5 years, and avoid susceptible varieties. (Source:
Ontario Berry Bulletin Agriphone For July 20, 2001)
Raspberry Cane Diseases - Pam Fisher, OMAFRA
Several pathogens can cause disease on raspberry canes. Identifying which
diseases are causing problems is the first step towards good control.
Anthracnose: The fungus causes conspicuous, pitted le-sions on the canes.
On primocanes, these lesions often have a purplish border, and are small,
oblong or squarish in shape and numerous. The lesions produce spores that
can spread to laterals and fruit in rainy conditions. An-thracnose can
weaken canes, reduce yield and vigour. This disease is frequently observed
on the cultivar Boyne. Qualicum also seems to be especially susceptible.
Spur Blight: The fungus invades canes near a spur, bud or node. Dark
triangle-shaped lesions develop at the base of the bud. During the winter,
these lesions turn whitish-grey. Spur blight can weaken buds and make
them more susceptible to winter injury.
Cane Botrytis: Like spur blight, cane Botrytis infects the cane at a
leaf spur or node, as leaves senesce. Dark brown lesions develop at the
base of the bud. Unlike spur blight, the lesions that develop from cane
Botrytis extend up and down the cane, and often surround several nodes.
Dark spore-producing structures, called micro-sclerotia, develop in infected
areas. These look like grains of black rice imbedded in the lesion. Infected
canes may be weakened and less productive, or die overwinter. I have seen
this disease frequently on Nova and Titan.
Cane Blight: Unlike the three diseases above, cane blight does not cause
noticeable lesions on the surface of the cane. This fungus invades raspberry
primocanes through wounds. A brown dicolouration is only evident when
the surface of the cane is scraped away (Figure 5). The fun-gus infects
the vascular tissue of the cane. Extensive in-fections may cause overwintering
canes to die. They are often brittle and break easily, because vascular
tissue has dried up. Canes that survive the winter may leaf out in spring,
only to collapse and die as harvest approaches.
Cane Gall: Outbreaks of this disease often occur follow-ing wet growing
seasons. Dark, warty galls erupt from infected tissue on fruiting canes,
often in very early spring. Soil-borne bacteria cause this disease, the
same bacteria that cause crown gall of raspberries. Infections occur through
a wound, by bacteria that are splashed from the soil to the wounded tissue.
(Figure 7) Cane gall is less serious to raspberry plants than crown gall.
However where cane gall occurs, be aware that crown gall may also be present.
Controlling cane diseases: Fungicides alone will not con-trol cane diseases.
Crop management practices are ex-tremely important. Keep rows narrow to
improve air cir-culation, and drying in the row. Do not over-stimulate
growth with excess nitrogen. Use a trellis to increase light levels reaching
the lower part of the cane. Leaves that drop off early because of low
light levels are espe-cially susceptible to cane Botrytis.
Pay attention to pruning and trellising practices and avoid wounding
primocanes. Wounds are an entry point for the pathogens that cause cane
bight and cane gall. Wounds can occur when new primocanes rub against
old pruning stubs, or trellis wire. Rough handling after harvest when
old fruiting canes are removed may also cause wounding of primocanes and
allow these diseases to infect.
Fungicides for cane disease management include lime sulphur and ferbam.
Lime sulphur is used in early spring before buds are 1/2 inch green. This
fungicide reduces levels of overwintering inoculum on last year's canes.
Ferbam is a protectant fungicide and is applied to protect new canes and
shoot growth from infection. It can be applied before bloom, and after
harvest. Do not spray Ferbam when bloom or fruit are present.
Mowing down infected plantings in early spring will break the cycle of
disease as it spreads from old fruiting canes to new primocanes. This
technique is used for fall-bearing raspberries, and in summer bearing
raspberries in a biennial system. It could be considered for severely
infested plantings in an annual system where growers are willing to forego
harvest for a year in order to bring disease levels under control. (Source:
The All Ontario Berry Grower, Vol. 00, No. 7, July 2001)
Grapes
Late Season Grape Disease Control - Bruce Bordelon, Purdue University
The first of July signals the shift from early season to late season
disease control strategy in grapes. From now until harvest the spray interval
can generally be extended to 14 to 21 days (depending on rainfall) and
growers must change fungicides. On most grape cultivars the last application
of mancozeb is recommended two weeks post-bloom because it has a 66 day
pre-harvest interval. One of the other protectant fungicides must be substituted
for mancozeb for the remainder of the season. Materials currently available
for late season disease control are captan, ferbam, and copper. The protectant
should be combined with one of the sterol inhibitors (SIs) such as Nova,
Bayleton, Rubigan, etc. Another option is one of the new strobilurin products
such as Abound, Flint, or Sovran. However, these may be a better choice
for the bloom and post bloom sprays because of economics. We are approaching
bunch closing so it is time to make an application for Botrytis bunch
rot control on varieties that are susceptible such as tight-clustered
hybrids (Vignoles, Seyval) and most vinifera, especially Riesling and
Pinot noir. Use either Rovral, Vangard, or Elevate and follow the guidelines
on page [98-99 of the New England Small Fruit Pest Management Guide -
SGS]. (Source: Facts for Fancy Fruit, No. 9, July 12, 2001)
More on Crop Estimation - Alice Wise, Cornell Cooperative Extension
From July 19, 2001 Vineyard Notes by Finger Lakes Grape Specialist Tim
Martinson, another method for crop estimation. "We are near 1200
growing degree days, traditionally a good time to weigh clusters for crop
estimates. Clusters achieve approximately 50% of their final weight at
1200 growing degree days [Riverhead is currently at 1500 GDD, so granted
it is a little late to ad-vocate this method though it is still interesting
to hear about]. This is a good time to estimate your crop - collect data
from representative 1 - 2 panel areas in the vine-yard. Count clusters,
and get average cluster weight by weighing at least 20 - 25 clusters.
Multiply by 2 to get an estimate of final cluster weight. Needless to
say, repeat this estimation procedure for each variety and block.
For Concords, 1200 GDD corresponds to the 'lag phase' - a pause in berry
growth between the 'cell division phase' and the 'cell enlargement phase'.
For other varieties of interest, timing might be different, and the 'multiplier'
may be different. It is important to check your actual harvested crop
against the estimates, and adjust timing and 'multiplier' accordingly."
Southeastern PA Winegrape Agent Mark Chien advo-cates a similar version
of crop estimation during the lag phase of berry growth. This is described
nicely by Steve Price in the Oregon Winegrape Growerís Guide. Lag
phase is associated with a hardening of the seed coat, about 55 days after
first bloom. At this time, 200 - 400 clusters are collected per block.
These are weighed and an average cluster weight is calculated. If doing
this for the first time, an assumption can be made that at this time,
clusters have reached half their final weight. As this process is repeated
for a few years, it can be fine-tuned. Chien points out, for example,
that Pinot Noir clone 4 was typically multiplied by 1.8 (instead of 2)
to get an estimated final weight. Like anything else in agri-culture,
this method is not full proof and is best done over a number of years.
(Source: Long Island Fruit and Vegetable Update, No. 20, July 20, 2001)
Meetings
July 31 Twilight Meeting at Wards Berry Farm
Tuesday, July 31, 5:30 - 8:00 PM., Ward's Berry Farm, 614 South Main
St., Sharon, MA
Contact: Frank Mangan (978-422-6374) for details.
Ward's Berry Farm was established in the early 80's by William and Ann
Ward. Since then, the focus has been high value specialty crops for retail
sale at the farmstand. A new year-round farmstand has been open as of
January 2001.
Business is operated by sons Jim and Bob Ward with lots of part-time
and some full-time help. Field crops include sweet corn, pump-kins, tomatoes,
gourds, decorative corns, strawberries, blueberries, squashes, beans,
peas, root crops, some IPM. Production greenhouse also. School tours,
parties, pick-your-own, and wholesale. Added value goods.
Directions: Interstate 95, Massachusetts Exit 8 (This is the segment
of 95 between Boston and Providence.) Can be accessed from Rte 495 or
old Rte 128. Go east, toward Sharon 1/2 mile (past Shaws Plaza). Farm
is on the right (yellow sign).
Mark Your Calendar for Massachusetts Marketplace 2001
Nearly 100 Bay State farms and food companies will showcase their products
at the sixth annual Massachusetts Marketplace Festival on Friday, August
24th and Saturday, August 25th at Elm Bank Reservation on the Wellesley/Dover
line. The Massachusetts Department of Food and Agriculture and the Massachusetts
Horticultural Society sponsor the event.
The Massachusetts Marketplace is an outdoor exhibition of new, unusual
and traditional local food, agricultural and horticultural prod-ucts for
both the trade and the public. Past exhibitors have included organic breads,
farmstead cheeses, miniature roses, ostrich meat, maple syrup, llama fiber
crafts, soups, wines, annuals and perennials, and organic produce.
For the first time, the public will be invited to purchase tickets to
Friday's exclusive preview reception. Non-industry guests will be wel-comed
between 3:00 pm and 5:30 pm. Tickets are $25 and can be purchased by calling
the Mass. Horticultural Society at 617-536-9280.
Saturday the Massachusetts Marketplace becomes a public festival. Consumers
can sample and purchase products and enjoy demonstra-tions, entertainment
and children's activities in a fun-filled atmosphere. Saturday's attendance
is expected to be well above last year's re-cord crowd of over three thousand
consumers. Admission on Saturday is $4, $3 for Mass. Horticultural Society
members and free for children under 12. Call the Mass. Horticultural Society
at 617-536-9280 for more information. "The Massachusetts Marketplace
edu-cates the public, food industry decision-makers and government policy
makers on the importance of the local food and agricultural sec-tor,"
said Massachusetts Commissioner of Food and Agriculture, Jonathan Healy.
"The Marketplace is the perfect occasion for our agri-cultural and
food producers to develop business opportunities," Healy added.
EVENT CONTACT: Mary Jordan, 617-626-1750, Mary.Jordan@state.ma.us
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