In this issue
Tree fruit news
§
Insuring the eradication of plum pox virus in
southwest
§ Sign-up for the fire blight tree assistance program ends June 29
Small fruit news
§ Post-bloom management of fruitworms in blueberry
§ Blueberry IPM workshops - June 13
§ Disease control in grapes critical during and after bloom
§ TNRC trapline data: Cranberry fruitworm
Other news
§ Regional reports
§ Weather news
Bill Shane and Mira Danilovich
District Fruit Educators
In July 2006, plum pox virus (PPV) was detected in a single
plum tree sampled at the MSU Southwest Michigan Research and Extension Center
(SWMREC) in
Under order of the Michigan Department of Agriculture and
with the guidance of the United State Department of Agriculture, SWMREC is
eradicating all peach, plum, nectarine and apricot trees (approximately 13,000
trees) within 500 meters of the block that once contained the PPV contaminated
plum tree.
The 500 meter eradication order issued by the MDA is similar
to action taken in
The quarantine will be cancelled when sampling of all
susceptible fruit bearing and ornamental trees in the quarantine zone is
negative for plum pox virus for three consecutive years. In the interim, much
of the activity of the MSU peach breeding program, including establishment of
new nurseries, will be moved to the MSU Trevor Nichols Research Complex near
As of June 4, 2007, 18 acres of peaches, nectarines, plums
and apricots have been uprooted at SWMREC, ending with the eventual removal of
all 24 acres of these fruit types. With the help of a Project GREEEN grant and
support of the Michigan Peach Sponsors, high value peach selections from the
MSU peach breeding program have been sent to the North Region Special Project 5
(NRSP5) virus-testing facility of
State Executive Director for the Farm Service Agency, Nancy Dietz, announced today that sign-up for the Tree Assistance Program (TAP), which provides financial relief to owners of eligible trees damaged by fire blight, ends June 29.
For several years, there has been a tree replacement program
specifically for
To qualify for payments, eligible owners must have suffered
losses of 15 percent or greater for an individual stand, adjusted for normal
mortality (1 percent for
For more information, or to apply for TAP assistance, tree owners should contact their local Farm Service Agency (FSA) office. Additional TAP information is available on FSA’s website at: www.fsa.usda.gov
Rufus Isaacs & John Wise
Entomology
With blueberry bloom almost complete in
Guthion, Imidan, Lannate, Asana,
Danitol and Sevin are effective broad-spectrum insecticide options available to
blueberry growers. With all these products, maintaining good coverage is still
important to get residue to the parts of the berry where fruitworms are found:
within the calyx cup of the berry where eggs are laid, and also at the stem end
where cranberry fruitworm larvae tend to enter berries. Use enough water and
consider spray additives to help spread the material across the berry surface.
EPA’s phase-out for Guthion will
remove this insecticide from blueberry production by the end of 2012. Given the
current reliance on this chemical for fruitworm control, it would be wise for growers
to gain experience with alternatives on a portion of their fields now so that
an effective program is in place when Guthion is completely restricted.
Some selective insecticides, like
Confirm, SpinTor, Entrust and Bts
might also be useful after bloom (See the Michigan Fruit
Management Guide, MSU bulletin E-154 for specific recommendations for each).
Recent research trials in
Correct timing and coverage are
critically important for fruitworm control, so regular scouting of fields, use
of sufficient spray volume to get good fruit coverage and selecting appropriate
spreader-stickers can maximize the increase activity of most insecticides
applied for fruitworm control.
Rufus Isaacs
Entomology
There will be two meetings for
The meeting will be presented by MSU Extension specialists
and educators in the morning in Van Buren County and in the afternoon in
For more information about these meetings, contact Keith Mason at (517) 242-5909 or masonk@msu.edu. RUP credits have been applied for.
Annemiek Schilder
Plant Pathology
The bloom and post-bloom period is a critical for disease control in grapes, as the young clusters are highly susceptible to diseases, including black rot, downy mildew, powdery mildew and Phomopsis. The risk is especially great if we have a lot of rain and moderate to warm temperatures during this time. Cool, wet weather during bloom can also allow Botrytis to get a foothold in the clusters of susceptible varieties by promoting growth on senescing flower parts.
The main aim for fungicide sprays at this time is to protect
the clusters from infection by these pathogens, while simultaneously protecting
the foliage as well. Some infections that occur during this period may remain
dormant (invisible) until the berries are close to veraison (black rot) or
ripen (Phomopsis, Botrytis). As the berries mature, they become naturally
resistant to new black rot, downy mildew, and powdery mildew infections and the
need for protection diminishes. This happens quite rapidly (two to three weeks
after bloom) for downy mildew, three to four weeks after bloom for powdery
mildew and four to five weeks after bloom for black rot. Some wine grape
varieties remain susceptible to black rot a couple of weeks longer than
However, be aware that the cluster stem (rachis) and especially the berry stems can remain susceptible longer than the berries in most cases. The only disease to which berries remain susceptible throughout their development is Phomopsis, but the risk of infection diminishes after bunch closing because spore release drops off then. Botrytis is more of a risk late in the season as the clusters become more susceptible after veraison, especially in tight-clustered varieties. In general, aim to protect the clusters from the major diseases from immediate pre-bloom until four to five weeks after bloom. If cluster development is variable, make sure that the latest developing clusters have caught up before easing up on the spray program.
Temperatures in the high 70’s and low 80’s are perfect for
black rot. At these temperatures, only six to seven hours of wetness are needed
for infection. Black rot is a tricky disease in that infections can remain
latent (dormant) for a long period of time, so you won’t know that you have the
disease until is it too late to do anything about it. Infections can take place
anytime from bloom onwards, but only become apparent at or shortly before
veraison. Grape berries are highly susceptible to black rot infection for the
first two to three weeks after bloom. Then they become progressively less
susceptible as they develop, finally becoming highly resistant about four to
eight weeks after bloom depending on the variety and year. In general,
In five years of trials in
Sterol-inhibitor fungicides (e.g., Nova and Elite) continue
to provide outstanding control of black rot, and provide several days of
post-infection activity. When using SI fungicides on a post-infection schedule,
use the highest label rates because post-infection activity is strongly
rate-dependent, particularly when extended “kickback” activity is required. The
strobilurin fungicides (Abound,
Cane and leaf lesions have been showing up in vineyards. The
extended rainy period that we are currently experiencing is conducive to
infection. Phomopsis spores were also plentiful in a
If at this time you find a lot of lesions on the leaves and
canes, infection pressure will be high for the fruit also. Best fungicide
options for control of Phomopsis during and after bloom will be Abound, Sovran
or Pristine (do not use Pristine on
No powdery mildew has been sighted in vineyards yet. However, we have had several occasions for primary ascospore release this spring. Ascospore discharge is initiated in the spring if 0.10 inch of rain occurs at an average temperature of 50ºF or more. This results in thorough wetting of the bark where the cleistothecia have overwintered. When the cleistothecia are sufficiently wetted, infectious ascospores are discharged within four to eight hours and are carried by wind to susceptible plant tissues. They can infect any green surface on the developing vine and do not need water for infection. The fungus then grows on the plant surface and produces a second type of spore (conidia), which are windborne and cause secondary infections. Under optimal conditions, the disease can spread rapidly, as the time from infection to production of conidia can be as short as seven days. Although infections can occur at temperatures from 59 to 90ºF, temperatures between 68 and 77ºF are optimal for disease development. Temperatures above 95ºF inhibit spore germination, and the fungus may be killed at temperatures above 104ºF.
Sulfur remains an effective and inexpensive protectant
fungicide for powdery mildew control in non-sulfur-sensitive grape varieties.
The most effective systemic fungicides for powdery mildew control are the
sterol inhibitors (Nova, Elite, Vintage, etc.) and the strobilurin fungicides
(Pristine, Sovran, Abound and
Downy mildew primary infections start if rains occur (at least 0.4 inches) and temperatures are above 50ºF over a 24-hour period. Check the recent weather conditions at your location on the MSU's Enviro-weather website. I think in many locations, the most recent conditions certainly qualify as a primary infection period for downy mildew. It takes 7 to 12 days for the lesions to form after infection has taken place, so keep an eye out for downy mildew. Early in the season, downy mildew lesions may be confused with low-concentration Gramoxone and possibly Chateau herbicide injury, which also cause yellow spots on leaves. However, if no herbicide was used and no herbicide spots are present on lower leaves, the spots may be downy mildew. Look for white sporulation on the underside of the leaf.
A spray for downy mildew at this time is recommended for susceptible varieties, especially in vineyards with a history of disease. Severe downy mildew infection can result in premature defoliation of the vine. Ridomil Gold MZ and Ridomil Gold Copper have excellent curative and protectant activity against downy mildew. Under moderate infection pressure, they will provide three to four weeks of protection. Of the strobilurins, Pristine, Abound, and Sovran are good choices. Other effective fungicides are mancozeb, ziram, and fixed coppers. ProPhyt and Phostrol are also good alternatives: they provide excellent curative action and about 7 to10 days of protective activity. Under high disease pressure or when spraying after an infection period, use higher rates.
Mark Longstroth
Bill Shane
Greg Vlaming
Last week was hot. Highs were in the 80s and lows in the 60s. With moist soils, all crops made good growth. A cold front moved through the region on Saturday, June 2, with a rain event Sunday and Monday. Precipitation totals were about 0.5 to 1.5 inches of water, with less rain falling close to the lake. A long wetting period of 40 to 50 hours at about 65ºF was a major infection period for all fruit diseases. The forecast is for cooler weather with showers and temperatures in the 70s forecasted this week.
Only a few rose chafers have emerged. Potato leafhoppers are easier to find. Plum curculio damage is common, but we expect that most of the damage from this generation has already occurred. We don’t except much more in the future.
|
|
Grapes from April 1 |
|||
|
Location |
GDD 42 |
GDD 45 |
GDD 50 |
GDD 50 |
|
1171 |
980 |
708 |
610 |
|
|
1268 |
1074 |
786 |
649 |
|
|
1048 |
867 |
608 |
528 |
|
Peach fruit are 20-25 mm in diameter and small fruit are dropping. We are not yet at pit hardening. We are finding Oriental fruit moth larvae feeding in the fruit. Oriental fruit moth trap catch is low. Flight of the first generation has ended, and the second generation of Oriental fruit moths should be emerging soon, so pheromone traps should be renewed. Growers should protect susceptible varieties from peach mildew or rusty spot. Rust spot symptoms have been reported.
Tart cherries moved quickly in the warm weather and fruit are yellowing. Growers should not apply ethephon until all the fruit on a tree or in an orchard has changed color to yellow. Maintain protection for plum curculio and cherry leaf spot. Cherry leaf spot symptoms are appearing in many tart cherry orchards. Now is the time to put out cherry fruit fly traps.
Sweet cherries are straw-colored and early varieties are coloring. We had a significant drop of aborted and injured fruit last week. Growers need to protect against plum curculio and brown rot. Now is the time to put out cherry fruit fly traps.
Apple fruits are 0.75 to 1.25 inches in diameter. We had a heavy drop, and the fruit set looks good in most orchards. Fire blight symptoms are becoming common. The weekend rain probably removed almost all the primary scab spores. Growers should check their orchards for scab lesions on the leaves and determine if they should maintain fungicide protection. The waxy fruit is not very susceptible to scab infection at this time, but young leaves are very susceptible. Codling moths were biofixed on Wednesday, May 9 (325 GDD50 at SWMREC). We are past the peak of egg laying. We are catching Obliquebanded leafrollers. Biofix was last week at 950 GDD base 42. Treatment is timed for 450 GDD after biofix at peak egg laying. The second generation of Oriental fruit moths should be emerging soon and pheromones should be renewed in traps. European red mites are scarce and were probably reduced by the heavy rains. Rosy apple aphids are curling leaves, and green apple aphids are feeding on shoot tips. Growers may want to treat young nonbearing trees to control potato leafhopper.
Pear fruit are 25 mm in diameter. Pear rust mites are browning leaves in unsprayed trees.
Blueberries have green fruit. Shoot growth has stopped, but many shoots have begun a new flush of growth. Cranberry fruitworm are still flying and fruitworms can be found feeding in the fruit. Growers should apply fungicides to reduce anthracnose fruit rot later. Be sure to check the new Blueberry IPM Newsletter at the MSU Blueberry Site.
In grapes,
Strawberry harvest from matted rows has begun. The fruit ripened rapidly in last week’s heat. Growers may want to treat young plantings to control potato leafhopper.
Summer raspberries have green fruit, and the crop looks good.
Cranberry shoots are elongating and flower buds are emerging.
The next Monday Fruit Update
meeting will be Monday June 11, 5:00 PM, at the Fruit Acres Farm in
There is a Blueberry IPM meeting on Wednesday, June 13, at
10:00 AM to noon at Bodtke’s Main Farm on
A series of twilight grape scouting IPM meetings will start
next week. The dates and locations are; June 14 at Tim Seppala's farm, east of
With warm temperatures and more than adequate amounts of rainfall at most farms over the last week, we have seen a wonderful flush of growth of fruit and foliage in all of our fruit crops. With these storms, we have also seen several new insect pests as well as more fire blight and apple scab symptoms.
Rainfall over the region brought around 0.75 to 1.0 inch of rain over the weekend, however there have been several reports of rainfalls in the range of 2 to 3 inches. Needless to say our soil has adequate moisture supplies. Newly planted tree and small fruits are looking very good with the heat and the abundance of rainfall over the last week. The season is running about five to seven days ahead of normal in terms of degree day totals and a few days ahead of normal in terms of tree growth or phenology.
|
|
|||
|
Location |
GDD42 |
GDD45 |
GDD50 |
|
Commerce ( |
1016 |
831 |
576 |
|
Emmett (St Clair) |
957 |
782 |
543 |
|
|
1009 |
827 |
579 |
|
Lapeer (Lapeer) |
1001 |
823 |
578 |
|
|
1124 |
933 |
667 |
|
Romeo ( |
989 |
820 |
575 |
Apples in the
New pest problems to report in apples this week include potato leafhopper adults, two-spotted spider mites and more fire blight showing up. Potato leafhopper adults have been seen in moderate levels in many blocks of apples, as well as all of our other tree and small fruits. Codling moth trap catches are generally on the rise, with most all farms biofixing in the last two weeks. We are seeing good numbers of codling moth in traps in non-mating disrupted blocks. This is a good indication that mating disruption continues to be effective. Oriental fruit moth trap catches are generally down. Apple grain aphids and green apple aphids are being seen in increasing numbers. Wooly apple aphids continue to be seen here and there, however I did see one good colony affecting rootstocks last week. Spotted tentiform leafminer mines are showing up in a few blocks of apples, however their numbers are fairly low. San Jose scale adults are starting to be caught in traps. Dogwood borer larvae continues to be active in rootstocks. European red mite egg laying has continued across the region, however their numbers are generally low. Predators seem to be working hard at keeping their numbers low. Twospotted spider mites were seen in increasing numbers last week. I continue to see numbers of predators rise over the region, which is a good sign for the rest of the season. Mullen bugs are being seen in increasing numbers, however now they are predators feeding on aphids and mites. Early in the season, they were considered a feeding pest and caused considerable damage in several blocks across the region.
Rain brought a heavy infection period to all of our reporting stations on Saturday, Sunday and throughout the day on Monday. The long wetting period even extended over to this morning at some weather stations. We continue to catch apple scab spores at both of our monitoring stations, however, numbers are now on the decline as we are headed toward an end. However, I want to emphasize that we are not at the end of primary apple scab season. Apple scab lesions are now being seen on foliage and fruit. Fire blight strikes are being seen in more orchards over the last week. Some of these strikes are from trauma blight caused by high winds. There are also a few blocks with blossom blight infections becoming more evident. Streptomycin burn continues to be seen at most farms across the region.
Pears are at 20 mm to 22 mm in size. Pear psylla adults continue to be seen, however they have been controlled at most farms in the last few weeks. I’ve seen fire blight strikes in a few blocks of pears.
Peaches also continue to size quite well, with Red Haven being in the range of 21 mm to 1 inch in diameter. Thinning is beginning on peaches. I also could see some good numbers of potato leafhoppers in peaches across the region. Green peach aphids continue to be seen, however their numbers are being reduced dramatically by predators.
Sweet cherries are sizing quite nicely and are mostly at 18 mm to 21 mm in size. I’m seeing some reddening fruit develop as well as some fruit drop, however most of this fruit has been damaged either by insects or birds, and will most likely continue to drop to the ground. However, based on the early straw-coloring of fruit, I think that our harvest season is going to be ahead of normal. It will most likely begin late this month. I continue to see potato leafhopper in sweet cherries, as well as a few black cherry aphids. Bacterial spot infected older foliage continues to be seen, and some of those leaves are dropping to the orchard floor.
Tart cherries are mostly at 13 mm to 14 mm in size. Again, I continue to see potato leafhopper, mostly at low levels. Cherry leaf spot and bacterial spot infected leaves continue to drop in tart cherries as well.
Plums are sizing
quite nicely with most around 20 mm to 22 mm in size.
Strawberries have
mostly finished bloom, and we are now starting to see some fruit that is
getting closer to being ripe. Farms in the southern part of the region have
opened for harvest in the last few days. In the
Raspberries continue to be in bloom for summer red raspberries. Fall red raspberries are now about 20 to 24 inches in length and look fairly good with no major pest problems to report. The only pest problem to report is potato leafhopper in raspberries.
Blueberries are at 10 mm to 12 mm fruit size for the larger fruit. We’ve seen a tremendous amount of new foliage develop over the last week, they are finally looking a bit more normal in terms of leaf growth. Cranberry fruitworm and cherry fruitworm have been controlled at most farms over the last week.
Phil Schwallier
Amy Irish Brown
Carlos Garcia-Salazar
Many apple fruits are at the 20 to 25 mm size, and much too
large for chemical thinners to have any effect. Recent stormy weather brought
some hail and high winds through the
We most likely had our last apple scab infection over the past weekend starting with rains in
the early morning hours on Saturday, June 2. There was a very light number of
spores discharged with this initial rain event, but no other spore found in the
additional rain events on Saturday evening and Sunday. I will continue to check
spore rods until this low pressure event moves out of our area, but I don’t
expect to find any more spores for 2007. You needed to be covered for this
latest rain event, which did result in a heavy apple scab infection for the
general
There are just a few strikes of fire blight on blossoms being reported in commercial orchards. Growers have done a good job protecting from blossom blight this year. The recent hail and high wind event caused a trauma blight situation and orchards needed to be covered up in fire blight susceptible varieties.
A regional biofix for Oriental fruit moth was set for
A regional biofix for codling moth was set for May 20. This
date might be too late or too early for a few blocks, but it should work for
the majority of acres around
European red mites were relatively common this year and many blocks that have a petalfall miticide are looking good. In blocks without any controls so far, adult European red mite can be found, and newly laid eggs can also be found. The recent hot temperatures really pushed European red mite development over the last week in blocks with no controls on yet.
Green apple aphids are now present and starting to form colonies.
There has been summer-like weather conditions with daily
temperatures into the 80’s and lows in high 50’s to low 60’s. Humidity was high,
but no precipitation before Saturday, June 2. It started as scattered showers
then by Sunday, developed into a more wide-spread event. Out of this system,
Crops are developing very nicely. It looks like a full crop of apples, pears and peaches. Cherries are a bit thin in some spots, but overall, the crop potential looks about the same as last year or slightly above. For now it promises excellent quality! Sweet cherries have started to change color and are looking very good.
West
|
Location |
DD42 |
DD45 |
DD50 |
Rainfall last week |
Rainfall since 4/1 |
|
Hart |
945 |
771 |
532 |
0.41 |
5.07 |
|
Ludington |
857 |
694 |
474 |
0.42 |
5.22 |
|
Manistee |
923 |
753 |
520 |
1.1 |
4.76 |
The previously mentioned rains were infection events: two
infection periods for apple scab in
These rains were infection rains for cherry leaf spot as well. Scouts and consultants are reporting finding cherry leaf spot lesions mainly in the blocks that had severe problems last year. Bacterial canker is showing in sweet cherries. Well-defined symptoms are present on spurs and on the fruit.
Codling moth applications are still going on depending on the “floating” biofixes. We had biofixes from May 15- May 28. European red mites are a problem in a few isolated pockets. Scouts are reporting first catches of obliquebanded leafrollers. Plant bugs are being found in higher numbers than previous years. Tufted apple bud moths are flying. There are quite a few potato leafhoppers around.
Growing
degree day accumulations at NWMHRS
GDD42 874
GDD50 482
Growth
stages at NWMHRS (6/4/07—8:00am)
Apples have 15 mm fruit.
Pears:
Sweet cherries: Hedelfingen, Gold, and Napoleon have 12-13 mm fruit.
Tart cherries: Montmorency and Balaton have 12-13 mm fruit.
Apricots have 32 mm fruit.
Plums have 13 mm fruit.
Grapes: Chardonnay have 10-16 inch shoots.
Last week, we had very hot, dry weather, especially for May.
The weekend brought rain into the area, but it seemed to be extremely spotty. For
instance, the NWMHRS recorded 0.43 inches of rain, while Jim Nugent’s farm on
The weekend rains have resulted in apple scab infection periods at all weather stations throughout the area, despite the spotty actual rainfall. All infection periods are considered to have a high level of infection, especially with the duration of wetting events lasting 50-70 plus hours. Based on the apple scab model, spores are at 100 percent maturity and are about 90 percent plus discharged. We predict that these rains will discharge the last of the mature spores, and we hope to call an end to primary scab in the near future. Powdery mildew is starting to show up in apples. Fire blight is also present in some susceptible varieties in the region.
Spotted tentiform leafminer traps only caught an average of 39 miners per trap. Codling moth trap counts were up at the NWMHRS this week with 14 moths per trap. We captured our first obliquebanded leafroller adult this week, and we are still catching Oriental fruit moth.
As mentioned above, the weekend rains have extended into Monday, which have resulted in a high cherry leaf spot infection. Cherry leaf spot control is crucial at this time with these prolonged wetting periods and rapid leaf growth. We have observed European brown rot in Balaton at the NWMHRS as well as some other blocks in the area. We have not seen this disease in Montmorency so far this season. However, we did find some American brown rot on Montmorency tarts in an isolated incidence. Powdery mildew is just starting to be visible on cherry leaves in a few orchards.
We captured a few more obliquedbanded leafrollers in cherry than in apple with four moths per trap. Lesser peachtree borers are flying in higher numbers this week (about 13 moths per trap), while American plum borers are on the decline. We are still catching plum curculio in our traps, and we have observed oviposition damage in both tart and sweet cherries. With these cool temperatures, plum curculio will slow down, but will resume with increase in temperature.
In grapes, potato leafhoppers have arrived full force to the northwest. We are seeing adults, as well as some leaf cupping and yellowing of leaves. Because of the dry weather, we have noticed some deficiencies showing up but we have not clearly identified them as of yet. Powdery mildew has also been noticed in a few vineyards in the area.
Jeff Andresen
Agricultural Meteorology
Geography
The upper air trough that brought showers and thunderstorms
to much of
Windy and much warmer weather will be likely statewide Thursday, prior to the passage of a cold front from west to east overnight Thursday into Friday. Daytime temperatures Thursday will surge into the 80's to near 90EF and fall only into 60's Thursday night and strong southerly winds from 15-25 mph will hinder any spraying operations. The front will set off at least scattered showers and thunderstorms in western sections of the state late Thursday and early Friday in the east.
Following the frontal passage, high pressure is expected to move in for the weekend, leading to cooler, fair and dry conditions Saturday and Sunday. Temperatures will fall back to near normal levels over the weekend, with highs generally in the upper 60's to mid 70's and lows in the 50's. Rainfall will be possible once again by Tuesday of next week.
Further ahead, medium range forecast guidance is consistent
in calling for the formation of an upper air troughing feature across western
sections of the