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| Fruit Crop Advisory Team Alert newsletter | ||||
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| Vol. 22, No. 9, June 5, 2007 |
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| In this issue Tree fruit news  Insuring the eradication of plum pox virus in southwest Michigan Sign-up for the fire blight tree assistance program ends June 29Small 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 fruitwormOther news Regional reports Weather news |
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| Insuring the eradication of plum pox virus in southwest Michigan 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 Benton Harbor, Michigan (view images). PPV is a serious disease of stone fruit that can cause significant yield and quality loss. PPV has been the most significant disease of stone fruit in Europe for many decades and was detected for the first time in Pennsylvania in 1999, Ontario in 2000 and in New York and Michigan in 2006. The Michigan Department of Agriculture (MDA) has worked very intensively since that time to test the Prunus trees at risk at this and other Michigan locations. After testing more than 50,000 samples in late summer, no new “positives” were found in Michigan. 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. Plum pox virus strain D, the type detected at SWMREC, will not infect cherry, but can infect several other Prunus species such as dwarf flowering almond (P. glandulosa), black thorn (P. spinosa), and Japanese flowering cherry (Prunus serrulata), among others. |
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| The 500 meter eradication order issued by the MDA is similar to action taken in Pennsylvania to deal with a much larger plum pox virus contamination problem. Because plum pox virus is a disease that is slow to show symptoms, the extensive eradication zone around a detection site is necessary to eliminate the possibility of latent infections. The 500 meter eradication zone is part of a larger quarantine zone of approximately a two-mile radius and a larger nursery stock regulated area of 7.15 mile (11.5 km) radius around the positive plum pox virus site (see Fruit CAT Alert issue Vol. 22, No. 1, March 27, 2007). 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 Fennville, Michigan. 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 Washington State University in Prosser, WA. The extensive testing at Prosser with ELISA, PCR and indicator species will insure that these peach lines are clean. |
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| Sign-up for the fire blight tree assistance program ends June 29 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 Michigan producers who suffered tree losses because of fire blight from January 1, 2000, through the 2007 crop year, which ends September 30. Michigan producers, who suffered a qualifying loss due to fire blight, may apply for the TAP until June 29. Due to this special authorization, all eligible applicants with qualifying tree losses will have to submit evidence of the required replanting by August 31. This is Michigan’s fourth sign-up under this authorization. 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 Michigan fire blight TAP). Payments are in the form of 75 percent cost sharing to replace the eligible trees within 12 months from the date the TAP application is approved. 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 |
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| Post-bloom management of fruitworms in blueberry With blueberry bloom almost complete in Michigan, grower insecticide options for fruitworm control expand. Monitoring traps have detected increasing catches of cranberry fruitworm in the past week across southwest Michigan, and our scouting on Monday found fresh cherry fruitworm eggs in Van Buren and Ottawa counties. This emphasizes the need for protecting fruit from fruitworm infestation in the weeks after bloom. Once bees are removed from the fields, broad spectrum insecticides can be used. 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 Michigan have demonstrated that Confirm® applied after bloom to fields with low or moderate fruitworm pressure can also achieve control of these pests. This insecticide has the benefits of minimal negative impact on natural enemies such as parasitic wasps, ladybeetles and lacewings, plus long residual activity because of resistance to wash-off and ultraviolet breakdown. 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. |
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| Blueberry IPM workshops - June 13 There will be two meetings for Michigan blueberry growers held on June 13 to update attendees on insect, disease and weed management. The meetings will highlight scouting blueberry fields for key pests such as fruitworms, aphids, mummy berry and virus symptoms, and will provide results from some of MSU’s ongoing blueberry IPM research. Attendees will also be updated on new pesticide labels and a new weekly IPM newsletter produced for the blueberry industry. See it online at: http://www.isaacslab.ent.msu.edu/blueberryscout/blueberryscout.htm The meeting will be presented by MSU Extension specialists and educators in the morning in Van Buren County and in the afternoon in Ottawa County. The morning meeting will be from 10:00 AM-12:00 PM at the Bodtke family’s Cornerstone Ag farm on 57th Street in Grand Junction. This is north of CR 388 (Phoenix Road), a few miles west of Grand Junction. The afternoon meeting will be held from 3:00-5:00 PM at the Carini family farm (Carini Farms), 15039 Port Sheldon St., west of US 31 in West Olive. For both meetings, signs will be provided to guide people to parking off the road. At both sites, we will meet at the processing sheds and unless it is raining, will then move to a nearby field for the scouting demonstrations and talks. For more information about these meetings, contact Keith Mason at (517) 242-5909 or masonk@msu.edu. RUP credits have been applied for. |
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| Disease control in grapes critical during and after bloom 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 Concord grapes. 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. Black rot 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, Concord berries become resistant to infection about four to five weeks after bloom, while some V. vinifera cultivars don’t become fully resistant until weeks after bloom. Thus, the period from immediate pre-bloom through early fruit development is crucial to protect grapes against black rot infection. In five years of trials in New York, good black rot control was achieved with one immediate pre-bloom and one to two post-bloom fungicide sprays. The second post-bloom application is strongly advised if black rot has been a problem in the vineyard the previous year, and should be considered prudent if wet weather is anticipated. During three years of fungicide trials in a ‘Concord’ vineyard in Fennville, Michigan, just two post-bloom applications of SI fungicides have provided very good control under high black rot pressure. An immediate pre-bloom application is advised only if black rot was severe in the vineyard in question in previous years. 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, Flint, Sovran, Pristine) are excellent protectants but provide only limited post-infection activity (probably <24 h). Flint and Pristine should not be used on Concord grapes because of potential phytotoxicity. Phomopsis 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 Niagara vineyard in rainwater collected in mid-May, so the potential for infection is certainly there. Each rainfall event will lead to spore dispersal and can also lead to infection if the tissue remain wet for a sufficient amount of time. The optimum temperature for infection is 59-68ºF, at which time about 6 to10 hours of wetness are needed for infection. The longer the tissue stays wet, the more severe the symptoms will be. Since rachis and flower clusters are now fully exposed, we should be concerned with preventing Phomopsis infection of the rachis and fruit, especially in mechanically pruned vineyards and vineyards with a history of the disease. Rachis infections are most closely correlated with yield loss. 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 Concord grapes). Phosphorous acid fungicides, such as ProPhyt and Phostrol, are also good and cost-effective alternatives. These are systemic and will most likely provide some kick-back activity. In trials done in Michigan, ProPhyt provided very good control of Phomopsis when sprayed on a 14-day schedule. Tighten the schedule and increase the rate if disease pressure is high. Ziram is a moderate to good protectant against Phomopsis and can be a tank-mix partner with any of the phosphorous acid fungicides. EBDC fungicides are good protectants, but cannot be applied after bloom has started in grapes grown for the National Grape Cooperative. EBDC’s have a 66-day pre-harvest interval. Powdery mildew 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. Berry age has a marked effect on susceptibility to powdery mildew. Researchers in New York showed that when clusters of ‘Chardonnay’, ‘Riesling’, ‘Gewürtztraminer’, and ‘Pinot noir’ were inoculated from pre-bloom to six weeks post-bloom, only fruit inoculated within two weeks of bloom developed severe powdery mildew. Berries became substantially resistant to infection by three to four weeks after bloom, resulting in diffuse, non-sporulating colonies on berries, and were virtually immune at six to eight weeks after bloom. Also, rachises of ‘Chardonnay’ and ‘Riesling’ fruit clusters developed severe powdery mildew when inoculated at bloom, whereas rachises inoculated 31 days after bloom developed only trace levels of powdery mildew. Therefore, early sprays (from immediate pre-bloom until three to four weeks after bloom) are critical for preventing powdery mildew on the clusters. This usually coincides with critical sprays for black rot. 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 Flint). Luckily, we do not have any reports of fungicide resistance to strobilurins in the powdery mildew fungus in Michigan, but in some vineyards where sterol inhibitors have been heavily used for many years, they appear to be less effective than they used to be. New fungicide options that provide excellent control of powdery mildew are Quintec and Endura. Therefore, it would be best to not entirely rely on SI’s during the most critical period for fruit infection (immediate pre-bloom until three weeks after bloom), but alternate or tankmix with other effective fungicides. Downy mildew 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. |
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| Regional reports 1 -- Southwest Mark Longstroth Bill Shane Greg Vlaming Weather and insect update 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.
Tree fruit 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. Plum fruits are about 18 mm in diameter. Growers should be protecting against plum curculio black knot and brown rot. 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. Small fruit 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, Concord bloom is ending. Vinifera bloom is just beginning. The rain over the weekend was an infection event for grape diseases. Growers who did not have materials on for the June 2-3 rain should consider materials with back action. Phomopsis lesions were found on grape leaves and shoots. Treatments for grape berry moth should be timed soon. We expect to see rose chafer soon. Check the MSU’s grapes.msu.edu website for scouting updates. 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. Meetings The next Monday Fruit Update meeting will be Monday June 11, 5:00 PM, at the Fruit Acres Farm in Berrien County. There are RUP credits available for the Monday Fruit Update meetings. There is a Blueberry IPM meeting on Wednesday, June 13, at 10:00 AM to noon at Bodtke’s Main Farm on 01240 57th Street, north of Phoenix Road east of Grand Junction. There is a second meeting in Ottawa County at 2:00 PM. This meeting will review scouting of blueberry fields; weed, insect and disease control in the mid-season before harvest. There are RUP credits available for these two blueberry meetings. 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 Lawton; July 12 at Bob Dongvillo's farm, south of Scottdale; and August 19 at Lemon Creek Vineyards, west of Berrien Springs. These meetings start at 6:00 PM. For more information on these meetings, call Mark Longstroth at (269) 675-8313. |
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| 2 -- Southeast Bob Tritten Weather 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.
Tree fruits Apples in the Flint area are 20 mm to 23 mm for Red Delicious, with Empire’s and Ida Red’s near one inch. I have seen a bit of fruit drop over the last week, however I’ve not seen any great amount of fruit dropping. Overall fruit is still sitting a bit heavy in some varieties, I don’t feel as though we’ve seen the full affect of thinning applications that were made over the few weeks. 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. Plum curculio infected fruit continue to be seen in higher levels, however the pest is no longer a threat to any tree fruit crops. Small fruits 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 Flint area, I expect harvest to begin over the weekend or early next week. With the exception of potato leafhopper, I’ve not seen any new pest problems in strawberries over the last week. Weeds have become more of an apparent issue as they are getting to be good size over the last week. 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. |
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| 3 -- Grand Rapids Area Phil Schwallier Amy Irish-Brown Carol Garcia-Salazar Weather 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 Grand Rapids area, and some growers are reporting damage from hail, but it seems to be localized to a few areas. Tree fruit 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 Grand Rapids area. 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 Grand Rapids area on May 10. Adult numbers have consistently been increasing in traps over the last two weeks but have seemed to flatten out or taper off over the last few days. We are probably at a peak hatch for Oriental fruit moth right now and flagging of peach and other stone fruit shoots can be found. There is also some apple terminal feeding from Oriental fruit moth in some blocks. 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 Grand Rapids. We have accumulated 275 DD50 since May 20 and just over 300 DD50 since May 15. Egg hatch should be well under way now, but not at a peak level yet. 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. Plum curculio have been actively making ovipositioning scars in stone fruits and apple over the last 10 days. Damage could continue for another week or so, but many apples are getting too large to be a favorable egg-laying site for plum curculio any longer. Green apple aphids are now present and starting to form colonies. |
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| 4 -- West Central Mira Danilovich Weather and crop development 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, Oceana County has had three wetting events, while Mason and Manistee counties have been under the same ongoing wetting event that started more than two days ago. 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 Central Michigan growing degree day totals since March 1-June 4
Tree fruit The previously mentioned rains were infection events: two infection periods for apple scab in Oceana County and one very long, ongoing infection event in Mason and Manistee counties. Sunday’s rain did produce spore discharge. Scab lesions are being found in some blocks. Fire blight symptoms are showing up sporadically in mainly the southern parts of the district where we had some infections. 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. |
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| 5 -- Northwest Nikki Rothwell Duke Elsner Growing degree day accumulations at NWMHRS Growth stages at NWMHRS (6/4/07—8:00am) 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 Revold Road (less than three miles away) only received 0.07 inch of rain. Another example of drastically different rainfall, were the three day totals for Benzonia, which recorded over 2 inches of rain, while the NWMHRS and Old Mission recorded less than a ½ inch of rain. In a nutshell, there are large differences in the amount of rainfall throughout the region. The weather will be cool for a few days, mid-50’s to mid-60’s, and then will warm up again. Overall, temperatures will fluctuate considerably in the next week. Tree fruit 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. Small fruit 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. |
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| Weather news Jeff Andresen The upper air trough that brought showers and thunderstorms to much of Michigan during the past few days will move east of the region by Wednesday, June 6, leading to a brief period of fair and dry conditions. A warm front is forecast to approach from the southwest by late Wednesday, bringing a chance for showers and thunderstorms, especially across northern and western sections of the state. Temperatures Wednesday will be a few degrees below normal, with highs ranging from the mid 60's north to the mid 70's south and lows generally in the 50's. 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 United States with a ridge across the east. This would leave Michigan under southwesterly flow aloft with an active storm track across the Midwest. The official NOAA 6‑10 day and 8-14 day outlooks for the June 10-14 and June 12-18 both call for above normal mean temperatures statewide. During the 6-10 day period, precipitation is forecast to range from below normal levels in southeastern sections of lower Michigan to above normal in northwestern sections of the state. A similar but less variable pattern is forecast during the 8-14 day period, with totals expected to range from near normal levels in southeastern sections of the state to above normal in the northwest. |
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