Christmas trees
Field crops
Fruit
Home and yard
Nursery and landscape
Turfgrass
Vegetable
Diagnostic Services
Soil/Plant Nutrient Lab
Enviro-weather
Regional IPM Center
Pesticide safety
Organic: New Ag Network
Invasive species
Sustainable ag & food systems
MSU ANR departments
MSU Extension
Site index
Contacts/permissions
| Fruit Crop Advisory Team Alert newsletter | |||||||
|
|||||||
 |
|||||||
| Vol. 23, No. 10, June 10, 2008 |
|||||||
| In this issue Small fruit news Potato leafhopper control in winegrapes Post-bloom management of fruitworms in blueberry Warm wet conditions can promote anthracnose fruit rot in strawberries The challenges of disease control during rainy spells
Blueberry IPM Twilight meetingOther news Regional reports Weather news |
|
||||||
| back to top |
|||||||
| Potato leafhopper control in winegrapes Potato leafhoppers (Empoasca fabae) can cause significant injury to winegrape vineyards, causing leaf cupping, reduced shoot growth, and leaf yellowing. These symptoms are most evident in sensitive cultivars, which react to the saliva and cell disruption caused during feeding. The most sensitive cultivars are white vinifera (such as Pinot Gris and Chardonnay), although some hybrids (e.g. Cayuga White) are also quite sensitive to this insect. The injury can delay the establishment of young vineyards and can compromise the vine’s ability to grow a large canopy that is needed to ripen fruit. Potato leafhoppers arrive in Michigan on southerly winds each spring, although their timing and abundance vary greatly between years. A small number of leafhoppers can cause a sensitive response in vines, resulting in a low threshold for this insect in vineyards of sensitive varieties. Recent research at MSU by Marcel Lenz and Stan Howell on potted Pinot gris grapevines has shown that as few as one potato leafhopper nymph per leaf is sufficient to cause the typical symptoms and measurable reductions in vine growth. However, these studies also suggest that vines can recover from damage if the insects are controlled. We are currently working with Paolo Sabbatini to examine the response of vines with varying levels of resistance and different crop loads. |
|||||||
| Scouting for leafhoppers
In vineyards sensitive to this pest, early detection is the key to maintaining protection against injury. Weekly scouting should be done through the spring with more frequent spot checks immediately after rain storms from the south. Potato leafhoppers live on the undersides of leaves and on stems, and move sideways when disturbed. They are bright green and about 1/8-inch long. Shaking the foliage of a vine can be used to see if any adult potato leaf hoppers are present (they will fly off the vine), but this will not help in detecting the nymphs which cannot fly. Adult potato leaf hoppers arrive first and lay eggs in the leaves, and the eggs hatch into nymphs in early-mid June. Both nymphs and adults can cause vines to exhibit leaf injury, cupping, and shoot stunting, so it is important to count both stages. Cultural control of potato leafhopper Host plant resistance is the main approach that can minimize pest pressure from potato leafhopper. Vineyards of juice grapes or thick-leaves hybrid varieties tend to have minimal concerns with this insect. Chemical control of potato leafhopper Foliar applications: Application of an effective insecticide to the foliage can quickly stop potato leaf hoppers from feeding on the vines. Grape growers currently have a number of effective broad-spectrum insecticide options available, including Sevin, Lannate, Brigade, Danitol, Capture, Baythroid, and Imidan which will provide a week or more of protection on the treated foliage. Although they are all active on leafhoppers, the performance of all of these insecticides is reduced by leafhoppers moving to untreated parts of the vine that have grown since the spray was applied. This means that another application may be needed to control potato leaf hoppers that move into the vineyard after the earlier spray. To address this problem, growers now have a number of systemic neonicotinoid insecticides that have valuable properties for potato leaf hopper control. These provide long residual control because they are absorbed into the foliage after spraying, move within the plant to improve the chance of controlling the leafhoppers, and making them much less sensitive to being washed off. Members of this class of insecticides now registered for use in vineyards include Provado, Assail, Actara, and Clutch. Soil-applied applications: Systemic insecticides provide unique tools for growers because once the insecticide is in the vine, it should provide a long duration of protection against insects feeding on the leaves, stems, and shoots of grapevines. This group includes rosechafer, Japanese beetle, leafhoppers, scale and mealybugs. Once the insecticide is absorbed by the roots, it moves in the transpiration stream to the foliage. Insects feeding on the vines would then receive a dose of the insecticide, causing either repellency, or death. Potential benefits of this approach to insect control include: longer duration of residual control against foliar pests, protection of insecticide from wash-off, control of multiple pest types with one application, minimal worker exposure to pesticide residues, and reduced toxicity to natural enemies. To get the insecticide into the plant, the soluble insecticide is typically delivered through a drip irrigation system. This is preferable to banding under vines followed by irrigation or rain, as the product moves to the root system more effectively. Our recent research supported this, as we saw high activity only on vines trained to drip, but not in vineyards where the applications were made to the weed-free strip before a rain. There are currently a number of soil-applied insecticides labeled for use in vineyards for systemic control of insect pests, including Venom, Admire Pro, and Platinum. Organic options: Although we have not conducted replicated trials, organic growers have reported activity of one percent Stylet Oil against potato leafhopper. This product can cause temporary inhibition of photosynthesis, so it should be used with caution. Another organic option expected to provide control for a few days is the pyrethrum insecticide Pyganic. Neem containing insecticides such as Azadirect, Ecozin, and Neemix are also registered for organic producers.
|
||||||||||||||||||||||||||||||||||||
| back to top |
||||||||||||||||||||||||||||||||||||
| Post-bloom management of fruitworms in blueberry With blueberry bloom complete in much of Michigan and beekeepers removing colonies from fields, grower insecticide options for fruitworm control expand. Blueberries are at risk from infestation by cherry and cranberry fruitworm, two moth pests whose larvae have the potential to infest fruit at harvest and which can cause reduced yield if populations are high. During the past week, monitoring traps have detected increasing catches of cranberry fruitworm across southwest Michigan and cherry fruitworm moths continue to be trapped. Scouting of bushes has revealed fresh cherry fruitworm and cranberry fruitworm eggs on clusters in Van Buren, Allegan, and Ottawa counties, and the first entry holes of larvae into fruit have been found. This emphasizes the need to maintain active management of these pests and continue monitoring in the coming weeks after bloom, because fruitworm activity typically extends throughout June. Once bees are removed from the fields, broad spectrum insecticides become an option that growers can consider for protecting their berries from fruitworm infestation. Guthion, Imidan, Lannate, Asana, Danitol, and Sevin are effective broad-spectrum insecticide options available to blueberry growers. With all these products, maintaining good coverage of the clusters is still important, to get residue to the parts of the berry where fruitworms are found such as in the calyx cup where eggs are laid. The larvae of the two species chew into the berries in this location with cranberry fruitworm larvae preferring to enter berries at the stem end. Because these insects move over such a small distance, it is important to use sufficient water and to consider spray additives (spreader-stickers) that will help spread the material across the berry surface. EPA’s phase-out of 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 test alternative programs on a few fields this season, so that an effective fruitworm control program is in place when Guthion is completely restricted. There are many options for chemical control of fruitworms, including some recently-registered products such as Assail that has performed well in our recent trials and Delegate which we are testing this season for the first time. See our earlier article in the Fruit CAT Alert from May 20 for a description of these options and their performance characteristics . Research trials in Michigan have demonstrated that Confirm applied at 16 oz/acre after bloom to fields with low or moderate fruitworm pressure can also achieve control of these pests. This insecticide has the benefit 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. We expect similar performance from the recently-registered Intrepid at 12 oz/acre. In trials conducted at commercial blueberry farms over the past few years, a program that used Confirm during bloom followed by Asana post-bloom was effective against fruitworms. We are also testing a Confirm, then Delegate, then Assail program this season. For organic growers, formulations of B.t. such as Dipel, Javelin, etc. and the spinosyn insecticide Entrust provide good control, but they must be reapplied every four to five days and they are not resistant to wash-off. In fields with a history of high infestation by fruitworms and where traps continue to trap, an additional application of insecticide may be required to protect fruit. The residual activity of the previous insecticide and the amount of rain since the last spray will be critical determinants of the need for reapplication. Residual control under dry conditions ranges from a few days for B.t. up to a few weeks for Guthion, Confirm, and Intrepid. Few insecticide residues can withstand an inch of rain, although Confirm and Intrepid are the most rain-resistant of the current options. While decision-making during this wet time of year can be very challenging, it is important to maintain regular checking of fruitworm monitoring traps, to check the bushes in hot-spots for eggs or larval entry-holes into berries, and to think about the amount of rain since your last spray to protect the fruit. |
||||||||||||||||||||||||||||||||||||
| back to top |
||||||||||||||||||||||||||||||||||||
| Warm, wet conditions can promote anthracnose fruit rot in strawberries The warm, wet conditions of the past week promote fungal disease development in strawberries, in particular anthracnose fruit rot. Foliar fungal diseases, such as Phomopsis leaf blight, scorch, and leaf spot also develop more rapidly in response to lots of rain and leaf wetness. Since we are currently at harvest, it is important to scout for fruit rots. Most people are aware of Botrytis gray mold, which is also a risk, but fewer may be familiar with anthracnose fruit rot. Anthracnose fruit rot is characterized by dark, circular sunken areas on fruit. This disease is usually caused by the fungus Colletotrichum acutatum, but other Colletotrichum species may also be involved. The fungus may also cause petiole and runner infections, flower blight, and anthracnose crown rot. Flowers and ripening fruit are very susceptible to anthracnose fruit rot. The pathogen can spread rapidly through fruiting fields during rainy, warm periods. Irrigation to help cool down the berries may also contribute to spread and infection. The first symptoms of anthracnose fruit rot are light brown, water-soaked spots on ripening fruit. The spots quickly develop into firm, round lesions, which usually turn dark brown to black and become slightly sunken. Under humid conditions, salmon-colored spore masses cover the lesions. Spore production, spore germination, and infection of strawberry fruit are favored by warm, humid weather. This explains why we often see anthracnose fruit rot appearing later in the picking season. Conidia are produced in a slimy matrix and are easily dispersed by splashing rain or by insects, animals or people moving through the field. Infected berries eventually dry up and mummify and can become a source of inoculum for the following season. C. acutatum is known to survive in infected plant material for up to nine months. Anthracnose fruit rot is very difficult to control when environmental conditions are favorable for infection during harvest. Therefore, control measures must begin early in the season. When planting a new field, start out with disease-free planting material. However, it is very difficult to detect the fungus in planting material because it causes latent (invisible) infections. The best approach at this point is to choose a reputable source of planting material. The spread of inoculum in the field can be reduced by mulching row middles with straw and using drip irrigation rather than overhead irrigation. Fruit with anthracnose lesions should be promptly removed from the field to reduce inoculum levels, especially early in the harvest season. Anthracnose fruit rot can be controlled by applying fungicides like Captan, Cabrio, Abound, Pristine, Switch, or Captevate. Of these, Pristine, Switch, and Captevate also provide good to excellent control of Botrytis gray mold. Furthermore, Cabrio, Abound, and Pristine provide broad-spectrum control of foliar diseases. If you have angular leaf spot caused by Xanthomonas fragariae (a bacterium), this can only be controlled with copper products.
|
||||||||||||||||||||||||||||||||||||
| back to top |
||||||||||||||||||||||||||||||||||||
| The challenges of disease control during rainy spells Extended periods of wet weather spell feast for fungal plant pathogens, since they are highly dependent on moisture for spore dispersal and plant infection. While dry spells earlier this spring might have threatened to create a “famine” year for fungi, the tables have indeed turned. Repeated or continuous wetting of infected tissues over several days is particularly conducive to spore production as it allows thorough wetting of infected canes or other overwintering plant parts and promotes spore release. In addition, heavy rains assist rain-splash-dispersed pathogens in getting the spores to susceptible plant tissues. Furthermore, extended wetness periods (12-48 hours) provide ample moisture for spore germination and infection of plant tissues. Diseases in small fruit crops that are promoted by warm wet weather include Phomopsis diseases; black rot, downy mildew, and anthracnose of grapes; leaf spot, spur blight, and anthracnose of raspberries; common leaf spot, Phomopsis leaf blight, scorch, and fruit rots in strawberry; and rusts in raspberries and blueberries. While powdery mildew generally thrives under warm-dry conditions, it does need rainfall in the spring and early summer to release ascospores from overwintered cleistothecia. So, rainfall at this time will increase powdery mildew disease risk later this season. The challenge is to apply sprays before rainfall events – with as much rain as we’ve had it is likely that most protectant fungicides have been washed off. A study by Xu et al. (2008) showed that when Captan was applied to apple leaves, Captan loss was primarily due to wash-off by rain. In fact, as little as one mm of rain washed off about 50 percent of Captan. Subsequent rainfall did not result in much more loss of the fungicide. The results may be explained by the fact that most of the Captan on fruit/leaf surfaces following an application can be washed off easily, but the remaining deposit is more tenacious. This has to be taken into account and the application rate may be adjusted accordingly. During periods like these, especially when followed or accompanied by windy conditions, it is very difficult to get the fungicides on at the right time, e.g., before an infection. This may be further complicated by fields being flooded preventing access with sprayers. Systemic fungicides should be used to get: 1) better coverage, 2) better rain-fastness, and 3) kick-back (curative) activity. They generally provide better disease control during or after extended rainy periods. Products are usually rain-fast within a couple of hours of drying, although longer drying periods may be better. The table (pdf format) shows which fungicides for small fruit crops are systemic or have systemic components. If relying on post-infection activity, use them at the highest labeled rate for the crop. Do consider that even systemic fungicides work better when thorough coverage is strived for by increasing spray volume and spraying every row or every other row. The pre-harvest interval and re-entry interval should also be considered as we are at or approaching. |
||||||||||||||||||||||||||||||||||||
| back to top |
||||||||||||||||||||||||||||||||||||
| Blueberry IPM Twilight meeting When: Wednesday, June 11, 6:00-8:00 PM Where: Cornerstone Ag Enterprise, LLC (Bodtke’s), 01240 57th St., Grand Junction, Michigan; The farm is located just west of Grand Junction on 57th St, north of Phoenix Rd (CR 388). What: Timely updates for control of pre-harvest diseases, insects, weeds, and discussion on the irrigation needs of blueberries. This is a free meeting with a light dinner served at 6:00 PM. Spray credits available for attending. Hope to see you there! For more information, please contact Paul Jenkins at: jenki132@msu.edu; 517-432-7751. |
||||||||||||||||||||||||||||||||||||
| back to top |
||||||||||||||||||||||||||||||||||||
| Regional reports 1 -- Southwest Mark Longstroth Bill Shane Weather Summer arrived last week. Temperatures rose into the 80s with lows in the 60s. Heavy storms passed through the region Friday (June 6), Saturday and Sunday. These storms brought heavy rains and high winds, blowing down trees causing local flooding and erosion. Hail also fell in many areas. Rainfall totals from these storms varied from a one to three inches. Allegan County received much more rain (almost seven inches) than areas to the south. Most of these rains were disease infection periods. Heavy rains wash off protectant pesticides so growers need to reapply protectants or switch to systemic materials. The rains also restored soil moisture levels. We expect cool temperatures for a couple days. Expect warmer temperatures Thursday and Friday with highs in the mid- 80s and lows near 60ºF. Our GDD totals are about 10 days behind 2007, three to four days behind average.
Tree fruit |
||||||||||||||||||||||||||||||||||||
| back to top |
||||||||||||||||||||||||||||||||||||
2 -- Southeast Much needed rainfall finally arrived across the eastern part of the state. Unfortunately strong thunderstorms, hail and wind also came with this rain. Most growers received between 1.1 inch and 1.6 inches of rain over the last week, however because of the slow moving nature of some of these thunderstorms, some growers have had as much as 2.5 inches of rain. Strong winds with the fast moving thundershowers that moved across the region on Sunday, June 8 in the afternoon caused some younger trees to snap at the graft union, as well as causing some trellis systems to snap or lean badly. Some scattered amounts of pea size, hail, slushy to hard, were reported in Sunday’s thundershowers as well. A few farms had a significant amount of fruit damage, however at most farms it appears to have passed without a major problem. With the heat of the last week, our season is now back to normal in terms of the degree day totals as well as tree phonology. Southeast Michigan GDD totals for March 1 to June 9
Tree fruits Apples have sized dramatically over the last week with most being in the range of 21 mm to 24 mm. However, there are apples approaching one inch in diameter. Fruit appears to be thinning quite nicely in most apple blocks across the region with heavy fruit drop. New pests in apples over the last week include the arrival of potato leafhopper adults and wide spread reports of fruit growers seeing apple scab lesions. Potato leafhopper adults arrived with thundershowers late last week and over the weekend, with numbers being moderate in most blocks. Spotted tentiform leafminer mines are starting to be seen in a few blocks, however the numbers are generally low across the region. Oriental fruit moth larvae have been seen in a few apple blocks, and trap catches have generally been down. Codling moth trap catches remain higher this year than in most years, and I am even seeing some pretty good trap catch numbers in pheromone disruption blocks. I am not certain why we have higher trap catch numbers in disrupted blocks this year, but that’s the way this season seems to be rolling out. There have been a good number of aphids that I continue to see in apples, including low numbers of green apple aphid, rosy apple aphid and wooly apple aphid. Oyster shell scale crawlers are still being seen, and I have not seen any San Jose scale crawlers. Mite numbers are generally lower this week due to heavy rains. Apple scab lesions have been reported in many blocks of apples over the last week. I am seeing both top and bottom leaf scab. Most of the scab that I am seeing appears to have a yellow halo around the margin, indicating that it is indeed burned out. With each of the rains that we have had the last few days, I continue to catch apple scab spores, indicating that we are not at the end of primary apple scab season. These spore catches are currant as of rain showers this morning (June 10). I continue to see a very few fireblight strikes in blight susceptible varieties. Many growers applied streptomycin yesterday for trauma blight as a result of the strong winds of Sunday afternoon. Powdery mildew continues to show up in fairly low levels. Pears are 11 mm to 21 mm with a wide spread of fruit size. I think that some of these smaller fruits will drop over the next few weeks, however time will tell. Pear psylla (all life stages) continue to be seen in pears, specifically in suckers of poorly managed trees. Peaches are at 12 mm to 21 mm in size, again with a wide range of fruit sizes. Green peach aphid continues to be seen in low numbers. Bacterial spot infected leaves continue to be seen in a few blocks of peaches. Oozing from bacterial canker from the trunk continues to be fairly common this year. There will need to be extensive thinning in most peach blocks this year. Sweet cherries are nearing pit hardening and are generally 16 mm to 18 mm in size where fruit are singles, and a bit smaller where there are more than one fruit per cluster. Fruit is beginning to color. I would expect to see harvest to begin in about three weeks. I continue to see some fruit discoloration or scarring from early season cold injury. Tart cherries are mostly at 12 mm to 14 mm in size, and some scarring continues to be seen in this fruit as well. Plums are mostly at 20 mm to 22 mm for the larger fruit. I continue to see some bacterial spot infected leaves. Some blocks and varieties continue to see heavy fruit drop. Small fruits Strawberry harvest is now underway in the southern part of the region. Harvest is expected to begin late this week, over the weekend, or early this week in most of the rest of the region. I am starting to see some fairly significant amounts of spittle bug across the region, and some lesser amounts of slugs. A few growers have applied slug bait. Raspberries are now at fruit set for early summer bearing varieties, and fall bearing varieties are about 12 to 15 inches in length. Some early signs of orange rust are starting to show up in summer fruiting raspberries, and I continue to see some light amounts of anthracnose. Blueberries are pretty much at fruit set for most varieties; it appears that the frost/freeze events of the spring were not as severe as I had indicated last week. We need to have another week of growth in order to more accurately access the size of the blueberry crop this season. Cherry fruit worm and cranberry fruit worm covers are being applied at this time. |
||||||||||||||||||||||||||||||||||||
| back to top |
||||||||||||||||||||||||||||||||||||
3 -- Grand Rapids Area Degree day accumulations at the Sparta weather station continue to be right at or slightly ahead of average now. Heavy rains moved through the area over the recent weekend, bringing some much needed rainfall – two to four inches fell in the past five days. Most apples are in the 15 to 18 mm stage and even bigger. All tree fruits are gaining size very quickly with the rainfall we’ve had. Thinning is all but complete, and thinners appeared to have worked well in response to the warmer temperatures lately. Our last apple scab spores were caught with the rain on May 30. There have been heavy rains from June 5 on and no additional spores were found on monitoring equipment, primary scab is over for the greater Grand Rapids area for 2008. There is some primary scab showing up in some blocks – much of it is unexpected since the primary scab season has been rather dry compared to normal. It looks like much of the scab comes from infections back in early May. Growers are encouraged to monitor their blocks very carefully to make sure they are clean of scab before reducing fungicides to normal summertime rates. MaryBlyt had the general Grand Rapids area in a very high risk for blossom blight for the past weekend for any trees with open bloom. There was very little bloom left coming into the heavy rains and higher temperatures, but there was some – especially on newly planted trees. High winds were the primary concern over the weekend with the many storms that moved through. Any ripping or tearing of leaves from high winds would have caused a serious trauma blight situation and growers were encouraged to cover. A little hail was reported, but mostly in the eastern areas of the growing region and very spotty. Some fire blight blossom blight strikes are showing up from earlier infections, so monitor blocks closely for the next few weeks for any new blight and remove accordingly. No new egg laying scars from plum curculio continue to be found in any apples. We expected to hear of more activity than actually showed up. Growers will want to continue to scout closely for any damage in small apple fruits. Apples are subject to plum curculio damage until they reach about 20 or 25 mm. Most stone fruits are out of the window where plum curculio will cause any more damage. European red mite eggs are all hatched. A few newly laid eggs were found late last week. Continue to monitor mites closely. A regional biofix has been set for codling moth in the Grand Rapids area for May 24. We’ve collected 234 degree days base 50 since that biofix, so the timing is right for those early egg hatch timed materials to go on. Obliquebanded leafrollers are mostly all pupated. Flight for the summer generation could begin at any time. A regional biofix has been set for Oriental fruit moth on May 8. We have accumulated 428 degree days base 45 since that biofix, so egg hatch is probably near its peak level and second cover sprays will be needed – especially with all the rain we’ve had washing away residues. Some initial flagging is being seen and small larvae can be found boring into growing terminals of stone fruits. Small fruit Blueberries in Central Michigan, north from Van Buren, are in green fruit stage. However, north of Ottawa County we still find blossoms, mainly in late season varieties. Weather conditions affecting the Central Region during the past weekend brought four to five inches of rain and also some pea-size hail that caused minimal damage to blueberry bushes. A visual inspection conducted on Monday, June 9 around West Olive, Michigan and in blueberry fields between Holland and Grand Haven, showed that, although fields were flooded, there was no observable damage to plants or fruits. Thus, we are not seeing any reduction in the size of the blueberry crop as a result of these weather events. If nothing changes during the rest of the season, we are expecting a large blueberry crop, similar or larger than 2007’s that reached 93 million pounds. Regarding early season pest problems, there a few outbreaks of mummy berry shoot strike. These are showing up in blueberry fields of small producers that delayed the early applications of fungicides. We are also seeing some early Phomopsis in twigs. This damage is occurring in fields that had Phomopsis infections in late season shoot growth. Very often, growers are mistakenly identifying this damage as winter damage. The recommendation is that growers that find this type of damage in their fields take shoot samples to the MSU Diagnostic Services Lab or to their MSU Extension office for identification. Early season insect pests including cherry and cranberry fruitworms are very active and ovipositions are already reported in Allegan and Van Buren counties. At this time, growers need to be applying pest control measures against fruitworms. So far, the growing degree-day accumulation in South Allegan is about 616, and around Fennville, Michigan the accumulation is of 485 degree-days. In Ottawa County, degree-days accumulated since March 1 is 498, approximately. The blueberry harvest continued in North Carolina, Georgia, Mississippi and California. However, most blueberries in the market are from Georgia, and North Carolina. During the past five days, blueberry prices in terminal markets of Chicago and Detroit fluctuated from $22.00 to $31.5 per flat (12 1-pt cups w/lids). |
||||||||||||||||||||||||||||||||||||
| back to top |
||||||||||||||||||||||||||||||||||||
4 -- West Central This past week temperatures were finally where they need to be this far into the season. Highs were in the high 70s to low 80s and the lows were in the 60s. Rain and storm after storm on a daily basis through most of the week made the headlines. Oceana and Mason counties received more rain over the weekend then for the whole period from April 1 leading up to this weekend. Sunday’s showers seemed to be the most intense around noon dumping a lot of rain in a relatively short period of time and than continuing at the slow pace for the rest of the day. Soil moisture has been restored for at least the next several weeks. After the recent frost setback, the crop that was left is developing rapidly. Apples are from 10 to 16 mm in diameter depending on variety. The thinning window is closing rapidly. Applications need to go on this week as soon as the opportunity presents itself. By next week, the fruit will be too big to effectively respond to the thinners. Pears are 12 to 13 mm in diameter. They are in the thinning window at this time. Plums are 13.5 to 14 mm. Peaches are 15 mm. Tart cherries are 12.5 to 13 mm. They have five to six fully expended leaves and are in the optimum window for applying gibberellic acid. Sweet cherries are greater than 15 mm. West Central Michigan GDD totals from March 1, as of June 8
This past week there were three apple scab infection periods. The rain on June 3 and June 5 produced a spore release. Last scab spores were picked up following the rain between 8:00 AM and 4:00 PM on June 5. The consequent rains did not result in any new spore releases and catches indicating the end of the primary. This year the end of primary scab occurred 13 days after the petal fall at 1024 DD32 post biofix at green tip (McIntosh). Fireblight canker margins are expected to ooze any day now. There is possible trauma blight in areas hit with high winds. Nectria blight is starting to show in Romes and may be confused with fireblight or frost damage. For cherry leaf spot, the combination of frequent rains and favorable temperatures resulted in a series of infections throughout the district. Oceana County had two moderate (June 3 and June 5) and one heavy (June 7 through June 9) infections. Mason County had one moderate (June 3) and two heavy (June 5 and June 7 through June 9) infections. Manistee County registered two heavy infections on June 5 and June 7 through June 9. There are bacterial canker symptoms in cherries. All of the frozen cherries that have yet to fall off and cherries with frost scars are of concern particularly now that we have warmer temperatures, frequent rains and high humidity. There is increasing the potential for brown rot development. It is necessary to make an adjustment in the regular protection programs to include materials that are affective after brown rot. Peach rusty spot and peach scab control applications need to go on. Strawberry angular leaf spot applications need to go on. Codling moth trap catches have doubled since last week. The average trap catches are from less than one to 46 moths per trap. Codling moth: GDD accumulation post biofix as of June 9
American plum borer numbers have gone up significantly. Lesser peach tree borer numbers are up. Scouts have reported the first greater peach tree borer catch last week. Borer complex applications/trunk sprays are recommended at this time and for the next 7 to 10 days. Tarnished plant bug is moving into the apple and peach blocks. Oriental fruit moth flight is still strong. Red banded leafroller numbers are still quite high at 6.5 moths per trap. Plum curculio is becoming more active again. There are increased numbers of trap catches as well as increased numbers of fresh scars on the fruit. There are relatively low numbers of aphids, mites and leafrollers. Potato leaf hoppers are beginning to show up in blocks throughout the area. |
||||||||||||||||||||||||||||||||||||
| back to top |
||||||||||||||||||||||||||||||||||||
5 -- Northwest Growing degree day accumulations at NWMHRS Growth stages at NWMHRS from June 9 at 3:00 PM Apples are 10-12 mm. Bartlett pears have 13 mm fruit. Sweet cherries: Hedelfingen and Napoleon have 12 mm fruit. Gold have 11 mm fruit. Tart cherries: Montmorency have 12 mm. Balaton have 13 mm. Apricots have 24 mm fruit. Plums are 10 mm. Grapes have 10-16 inch shoots. Weather The northwest region has had some unusual weather as has been observed across the rest of the state. The latter part of last week’s temperatures increased to the high 70s and into the low 80s. Storms moved in for the weekend, where we received 1.25 inches of rain in three days. The June rainfall total is 1.6 inches here at the NWMHRS. Winds have been intense over the past week, and growers have had difficulty applying pesticide applications. The humidity has also been high, often over 90 percent, which has caused continuous wetting events. We are at 749 GDD base 42 and 388 GDD base 50 at the NW Michigan Horticultural Research Station. Crop report The results of the late May freeze are becoming evident across the region. Areas in the southern locales of the northwest sustained more damage than many northern sites. At this time, the apple crop is light throughout the northwest, and Benzie and Manistee counties seem particularly hard hit. Many apple growers are reporting low yields in many blocks. The sweet cherry crop is looking better than once anticipated; frost fruit on the tops of branches is falling off and the remaining crop is sizable. However, quality will be the issue as frost scars are evident on the hanging fruit. Sweet cherries are in the 11-12mm size range. The tart cherry crop is far less than we reported last week. Estimates for the northwest range from 90 million pounds down to 55 million pounds, and many growers believe they have only one-quarter to one-third of a crop. The Balaton crop is extremely low in the northwest, and we believe this small crop load is due to lack of pollination. Bee activity was at a minimum during much of cherry bloom, and past research has indicated Balatons have other pollination issues. Fire blight and apple scab continue to be forecasted in the northwest region. Almost two weeks of infection periods are predicted with the wet and warm weather last week and into this week. Apple scab sexual spores are all mature at this time, but only 80 percent are estimated to have been discharged. Based on this model, we are still in the primary scab season and recommend protectant fungicide applications. We have biofixed for codling moths in the southern areas of the region and sporadically as far north as the NWMHRS. Biofix for codling moths vary greatly by block and monitoring should be done in individual orchards. Spotted tentiform leafminer catches are decreasing, and we are continuing to catch Oriental fruit moths in the station trap line (15-20 per trap). Plum curculio is still active and laying eggs. Cherry leaf spot has been predicted at moderate to high levels throughout the northwest region. American plum borer have been caught in increasingly larger numbers (about 12 per trap at the NWMHRS) and lesser peach tree borer moth trap counts have increased numbers (28 per trap). The first greater peach tree borer was caught at the station on Monday. Green fruit worm moths continue to be caught in the station trap line, and larva feeding damage is visible on fruit. One male San Jose scale has been caught on Old Mission Peninsula in a sweet cherry block. The warm, humid weather is likely to cause increased plum curculio activity. Lastly, we are beginning to see the results of the weather with high levels of European brown rot infections particularly in Balaton orchards and American brown rot is sporulating on mummy berries in the NWMHRS pathology block. Small fruit Not much is moving in grapes, but grape berry moths have been caught in increasingly high numbers at the research station. The impact of the freeze has been seen in vineyards around the region. Phomopsis is visible on canes, which is a little unusual for the northwest region. |
||||||||||||||||||||||||||||||||||||
| back to top |
||||||||||||||||||||||||||||||||||||
Weather news Several rounds of severe thunderstorms brought heavy rains, strong winds, and hail to many sections of Michigan (and other sections of the Midwest) on a daily basis from June 6 through June 9, causing widespread property damage and loss of power for thousands. The thunderstorms brought widespread rainfall to the state with totals since last Friday generally ranging from less than one inch in far northern and southern sections of the state to more than six inches in some west central counties. While increasing the risk of foliar disease, the rain greatly eased or ended problems with dryness that had intensified during recent weeks. The severe weather outbreak across the Midwest was associated with a meandering frontal boundary and an unusually hot humid air mass in place across the region, strong wind shear (increasing winds with height), and a series of upper air disturbances moving southwest to northeast across the region. On a statistical note, the severe weather outbreak kept the United States on pace to approach or set a new record for the greatest number of tornadoes in a calendar year. An area of high pressure is expected to bring a drier, less active weather pattern to Michigan through early Friday, June 13. A cold front will approach from the west late in the week, however, bringing the likelihood of more showers and thunderstorms in far western sections of the state by early Friday and across most sections by Friday afternoon or evening. Given that somewhat similar synoptic conditions to last weekend are expected to be in place by Friday, more severe thunderstorms will be possible. Fair and dry weather is expected following the frontal passage on Saturday and Sunday. Temperatures during the next few days will fall back a few degrees with highs Wednesday through Friday generally ranging from the mid- to upper 70's north to the mid- to upper 80's south and lows from the low or mid- 50's north to the mid- or upper 60's south. Somewhat cooler temperatures are a good bet by Saturday and Sunday. Further ahead, the medium‑range forecast guidance generally calls for the formation of upper air troughs across western and eastern sections of the United States with an upper air ridge expected across central sections. This would leave Michigan and the Great Lakes region in northwesterly flow aloft, which typically translates to cooler and drier than normal weather conditions. Not surprisingly, the National Weather Service 6‑10 day and 8-14 day outlooks covering June 15 through June 19 and June 17-23, both call for mean temperatures across Michigan to fall to below normal levels. Precipitation totals during the 6-10 day period are forecast to remain at near normal levels, while below normal totals are expected during the 8-14 day time frame. |
||||||||||||||||||||||||||||||||||||
| back to top |
||||||||||||||||||||||||||||||||||||
Email the web developer.