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| Fruit Crop Advisory Team Alert newsletter | |||||||||||||||||||||
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| Vol. 22, No. 14, July 24, 2007 |
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In this issue Next issue August 7 |
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| Activity of codling moth insecticides on secondary pests John Wise, Trevor Nichols Research Complex David Epstein, Entomology Second generation codling moth adult flight has increased over the last 10 days at the TNRC, initiating a July 15 biofix for the upcoming egg laying and hatch period. Field reports suggest that at the same time apple growers will be planning to control codling moth, several secondary insect pests, including Japanese beetle, apple maggot and spotted tentiform leafminer may need to be managed. The following table includes a list of insecticides recommended for second generation codling moth control, and their activity on these secondary pests. Table 1. Activity of insecticides on secondary insect pests
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| Predicted peak 2007 apple harvest dates Phillip Schwallier, district horticulture educator and station coordinator Amy Irish-Brown, district ICM educator Clarksville Horticultural Experimentation Station Apple maturity for 2007 is expected to be a week to 12 days ahead of normal for most of the state, which experienced an early end of winter. As a result, bud growth developed across the state with an early bloom in all areas. This year however, the south part of the state was damaged by a severe freeze in early April. Bloom was extended and fruits did not set well on older wood. Many areas have an apple crop born of one year old wood, which bloom later than our recorded bloom dates. Predicted dates in the southern part of the state are less accurate than most years for this reason. There was an extended bloom which contributes to a less accurate prediction. Also, there is quite a variation in crop load. Trees with light crop loads will mature earlier than these predicted dates. Heavy cropped trees will mature after these predicted dates. The early bloom and weather following bloom, give us predicted harvest dates (Table 1) as much as 14 days ahead of normal. These predicted harvest dates are for the center or peak harvest of these varieties for CA storage. This year the 2007 predicted harvest dates are compared to the rough normal harvest dates and last year's predicted harvest dates. This year the state will harvest apples roughly five to seven days ahead of last year (Table 2). Hot temperatures during July and August will hasten the maturity of some varieties. Gala is notorious for ripening early when late summer temperatures are above normal. Other varieties are less prone to hot temperatures advancing fall maturity. Still other varieties ripen when cold temperatures occur at near harvest time. The normal harvest dates for other varieties are listed in Table 3 for the Grand Rapids area. This year's 2007 predicted dates are a rough estimate based on the McIntosh, Jonathan and Red Delicious predicted dates. Other areas of the state should adjust non-predicted varieties based on their own history. Table 1. 2007 predicted peak harvest dates
Table 2. 2007 predicted peak harvest dates compared to normal and last year
Table 3. Normal peak harvest dates for varieties for the Grand Rapids area
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| Post harvest sprays for cherry leaf spot Nikki Rothwell, NWHRS George Sundin, Plant Pathology Cherry leaf spot is the most important fungal disease of tart cherry in Michigan. The leaf spot fungus Blumeriella jaapii infects leaves with symptoms first appearing on upper leaf surfaces as small purple spots. As spots accumulate on leaves, the leaves turn yellow and fall. The amount of lesions required to cause leaf yellowing and drop is variable. Late summer (August, early September) defoliation reduces the ability of trees to store photosynthate in roots leading to an overall loss of vigor and leaving trees more susceptible to killing by winter injury. Early-defoliated trees also typically exhibit reduced flower bud formation and often set less fruit the following season. As harvest will be winding down for cherries, many growers will be considering post-harvest applications for cherry leaf spot. Considering the shortage of rain this season, the disease pressure has been much lower compared to seasons past. We have also seen very few cherry leaf spot lesions on cherry leaves in the region for these two reasons plus saving a spray, growers may want to opt out of a post-harvest spray. However, there are a few other factors to reflect on this season when deciding if a post-harvest spray is warranted: 1) Ethrel damage from the past two years, 2) drought-like conditions this summer, 3) mite numbers, and 4) predicting the precipitation for the rest of July and into August. All of these factors have caused stress to trees, and trees under stress can be more prone to winter damage. As many know, Ethrel (ethephon) damage has been observed in blocks all across the northwest, both in sweet and tart cherries. This damage occurred in the past when ethephon was applied during hot and dry weather conditions during 2006 and in many blocks in 2005. Trees under stress, particularly drought stress, become more susceptible to ethephon damage. Damaged trees exhibit excessive gumming, and branches lose their leaves. Growers with trees stressed by Ethrel damage in 2005 or 2006 (or 2007 if we should have any) should consider a post-harvest spray to ensure that excessive leaf loss from cherry leaf spot does not predispose trees to winter damage. Drought is another condition that will cause tremendous stress to trees. So far this season, we are approximately 2.5 inches below our normal precipitation levels (based on the past 26 year average). Trees that have been under stress due to lack of moisture may also be less likely to withstand severe winter conditions, so again, growers should prevent leaf loss due to cherry leaf spot. Mites are another stressor growers may not have considered when making a decision about a post-harvest disease application. Mites can cause early defoliation within the inner canopy of trees, and if that defoliation is combined with defoliation from cherry leaf spot, trees could head into the winter at a severe disadvantage. Lastly, we cannot guess as to the weather for the remainder of July and into August. Unfortunately, growers will have to gamble on the weather to decide if they will need a post-harvest application. Often growers do not notice cherry leaf spot later in the season until they observe lesions forming on the leaves, and at that point, it is often too late for control. However, at this time, growers should be scouting the tops of trees for yellow leaves. This indicator is usually the first sign of cherry leaf spot infections that occur at this time. The tops of trees tend to be more infected at this time because of reduced spray coverage reaching these high areas. Growers also need to keep in mind that even a relatively low level of infection now could spread rapidly if sufficient rain events occur in the coming weeks. Leaves typically defoliate a few weeks after they begin to show disease symptoms. Thus, the goal of a cherry leaf spot management program is to maintain a healthy canopy on trees at least through the end of September. This recommendation would ensure an adequate amount of leaves on trees into late October and beyond. The fungicide of choice for leaf spot control after harvest is chlorothalonil (Bravo). Bravo 82.5 WDG at a rate of 3 lbs./A provides excellent leaf spot control. In addition, Bravo is a broad spectrum fungicide and thus is not subject to fungicide resistance concerns. |
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| Northwest wine grape IPM update
The last IPM Update for northwest wine grape growers and vineyard managers will be held on August 3 at Leorie Vineyards at the base of the Old Mission Peninsula. This update will run from 3:00-5:00 PM. This meeting will feature Drs. Annemiek Schilder, Rufus Isaacs and Paolo Sabbatini. |
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| Regional reports 1 -- Southwest Mark Longstroth Bill Shane Greg Vlaming Weather The last two weeks have been hot and dry. Highs have been in the 70s and 80s. Scattered storms passed through the region last week dropping from a trace to several inches of rain, most sites received 0.5 to 1.0 inch of rain. Fruit crops are showing signs of drought stress, shedding older leaves, setting terminal bud and slowing fruit growth. Soils are still dry and soil moisture reserves are low. The forecast is for warmer weather. The dry conditions this season have resulted in very little disease pressure in most fruits.
Insects Japanese beetles are common. Tree fruit Peach growers are harvesting Summer Serenade, Garnet Beauty and PF7. Some Red Havens are being picked. Dry conditions are hastening ripening. Flavor and quality are very good, but fruit size is suffering due to lack of water. Western flower thrip damage is showing up on peaches. Peach constriction disease (phomopsis) is becoming more obvious, but is generally causing minor damage. Oriental fruit moth catch is down indicating the end of the second generation. The third generation should emerge at about 2400 GDD base 45, so pheromone lures should be changed in the next two weeks. San Jose scale damage to nectarine fruit was seen in our area. Cherries look good with little sign of cherry leaf spot. In apples, Pristine and Earligold are being picked. Codling moth catches for the area have increased with the start of the second generation. Biofix for high-pressure sites was July 14 and for lower pressure sites was approximately July 21. European red mite numbers are high in some orchards. Sooty blotch symptoms were found in minimumly sprayed orchards on Monday. Small fruit Blueberry harvest continues. Currently, we are picking Bluecrop, Jersey and Elliot. Growers are irrigating to maintain fruit size. Sprinkler irrigation is conducive to fruit rot development and fungicide protection is very important in these fields. Anthracnose and Alternaria can be found. Blueberry maggot is flying in some areas. Japanese beetles and blueberry aphids are out. Grape berry growth and shoot growth are slowing under the dry conditions. Grape berry moth trap catch numbers are up. The second-generation flight has started. Japanese beetle and grape leafhopper numbers are building. Strawberry growth is good where irrigation has been used and potato leafhopper controlled. Raspberry harvest is ending. Japanese beetles and potato leafhopper are easy to find. Miscellaneous Michigan Department of Agriculture tests for plum pox virus at the Southwest Michigan Research and Extension Center have been completed and were negative for 2007. Testing of the surrounding area and elsewhere in the state is ongoing. The next grape IPM scouting meeting will be 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 Continued drought has been the weather story for the region for nearly two months. Our soils remain very dry, and signs of drought stress on our fruit crops are more evident as each day passes. The greatest amount of stress is seen on newly planted tree and small fruits. Many farmers have received light rain showers over the two weeks, but in most cases the total rainfall has only helped to settle the dust. A very few lucky fruit farms have received significant rain from thundershowers over the last two weeks. Growers with irrigation systems are irrigating almost around the clock. Growers without irrigation systems are hauling water to newly planted trees and small fruits. Cooler temperatures have persisted over the region for the last two weeks; however our season is still running nearly two weeks ahead of normal. Southeast Michigan growing degree day totals for March 1 to July 23
Tree fruits Apples are mostly 2.5 inches in the Flint area. Fruit size is very good this year despite the drought. Lodi harvest is complete, with a few later summer varieties now being harvested. Most growers have completed hand thinning operations. Summer pruning of apples is now underway at most farms. Over the last two weeks, we’ve had low numbers of apple maggot catch, and only at a few orchards. One of these farms had a significant rain event that most likely triggered emergence. So with the widespread drought, apple maggot emergence has been delayed. When we do finally get rainfall, I expect that you will see a fairly good flush of apple maggot. Codling moth trap catches have started to increase as the start of the second generation is now underway. A few farms biofixed for second generation codling moth adult flight late last week or early this week. Japanese beetle populations seem to be on the downside across the region. If we get more rain, that number may go back up. Growers need to do a thorough job of scouting all of their fruit crops a couple of times a week to make certain that the Japanese beetles have not moved in. Japanese beetles are easy to control with a variety of insecticides; however with populations in neighboring woodlots being so high this year, you will find that a reapplication of an insecticide may be needed about a week or so later. The true difficulty with Japanese beetle control comes as crops are nearing or are in harvest. Currently, this is the situation for blueberries and peaches with split pit, where shorter pre-harvest interval insecticides will be needed. San Jose scale crawlers have slowed their movement a great deal. Most have now settled back under their scale for another year. Most folks had a few oriental fruit moth, however generally their populations are low. Larvae of obliquebanded leafroller are common across the region this last week. Fall web worm adults have begun to emerge and are doing their webbing. European red mite numbers are high in a many blocks of Red Delicious and are starting to move out from there. The population is building, so keep an eye on them. Apple rust mites are very heavy at a few farms; however most blocks have a lower population. We have seen great populations of mite predators in the last few weeks as well. Powdery mildew is more common now on apples. Sooty blotch and flyspeck cover sprays need to be included as growers are spraying the rest of the season. I have not seen symptoms yet. Pears have taken on a nice swell over the last two weeks across the region, with most being around 2.5 inches in diameter. Peaches continue to size and color well, with most at around 2.5 inches. Harvest of early varieties continues, with Red Haven to begin in about a week. I’m seeing continued leaf drop in many blocks of peaches. In some cases, it is caused by bacterial spot and others by drought stress. X-disease symptoms have been seen at a few farms across the region, also causing lead drop. Plums have not sized very much over the last two weeks, with most around 1.25 inches in diameter. However, color is starting to develop. Small fruits Strawberry renovation has wrapped up across the region. Newly planted strawberries are runnering well at this time. I have observed and had more reports of white grub problems than I have ever seen in my almost 30 years of working as a horticulturist with MSU. I continue to see a good number of new plantings that are suffering from severe potato leafhopper burn. There are also several new plantings that need to be watered badly. Remember to keep both renovated and newly planted strawberries watered well during these times of drought. Raspberry harvest is now complete for summer red and black raspberries. I saw a fair amount of cane collapse as we neared the end of harvest, most likely due to a combination of winter injury and drought stress. Fall red raspberries are being harvested across the region. Japanese beetle populations were heavy at many farms across the region; please do a good job of scouting. Blueberry harvest is underway across the region. Where irrigation has been applied, we have good berry size this year. Low numbers of blueberry maggot catch have been reported at several farms across the region over the last two weeks. Japanese beetle populations are starting to decline in blueberries. Grapes continue to grow well. I am seeing a fair amount of powdery mildew at many farms across the region. Miscellaneous July is a great time to do leaf analysis or tissue testing for tree and small fruit crops. |
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3 -- Grand Rapids Area Sweet cherry harvest is complete. Early peach varieties started to be harvested last week. Peach fruit size has been good or average, despite the very dry conditions we are under. Some rain has moved through the area over the last few weeks, with some areas getting about half an inch and other areas getting none. The rainfall has been very spotty and much too light. Irrigation continues. Non-irrigated, newly planted fruit trees continue to look quite stressed. Tree fruit pests Obliquebanded leafroller are past peak larval activity right now, and many are very large and pupation has begun. Numbers and damage from obliquebanded leafroller is way down this year in the Grand Rapids area. Second generation Oriental fruit moth should be just past their peak egg hatch and larval activity is probably at a peak. Cover sprays are still important in stone fruits, especially peaches. Growers should watch the pre-harvest interval (PHI) of cover materials carefully. Harvest is very early this year, so PHI’s may be more of a factor than in recent years. A new regional biofix for codling moth has been set for second generation on July 10. We have seen a definite decrease of flight and zeros for at least one week at most sites, giving us confidence to set a second biofix for second generation. We should be at early egg hatch now from that July 10 date, so cover sprays are becoming more important once again to manage codling moth in your apple blocks. European red mites continue to be a problem in some blocks, but many more predators are being found this week compared to the last few weeks. Continue to monitor mites. Green apple aphids continue to be found, but numbers are dwindling. Predators continue to be found in aphid colonies. There are still a few wholly apple aphids being found here and there, but numbers are very low. Growers in the Grand Rapids area have been dealing with Japanese beetle for the last few weeks. Numbers of beetles should be increasing, but instead, seem to be dropping off. If we get a good soaking rain, growers should be on alert to find more Japanese beetles in their fruit blocks; I don’t think their activity is over yet. When putting out cover sprays, be sure to add something in for summer diseases. It’s been dry and summer diseases probably won’t begin to express themselves on fruits until we get some rain, but fungicides will help prevent that. Retain applications should be put on about 30 days from anticipated harvest. Check out the article in this CAT Alert issue with predicted harvest dates. Some of the early apple varieties are getting close to the 30-day window for Retain applications. |
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4 -- West Central In the last two weeks, the weather has been relatively cool. Temperatures have been in high 60 to low to mid 70’s for highs and the lows were generally in the 50’s. The main story has been the lack of precipitation. Our area has been in moderate drought conditions. Soil moisture is low and is being depleted through high daily evapotranspiration rates. Surprisingly, fruit size is not as bad as one might expect given the lack of moisture. Cherry harvest is wrapping up. As of July 14, the West Central region has harvested 39.8 million pounds. The latest weekly raw product report for the fourth week has not been posted yet at the time of this report. Information regarding harvest is posted on the CIAB web site at http://www.cherryboard.org/ . West Central Michigan growing degree day totals since March 1 as of Monday, July 23
Tree fruit Disease situation varies from block to block. In some, there are visible symptoms of scab on the leaves and on the fruit in apples, pears and peaches. Fireblight that is present is the result of the trauma sustained earlier in June. There is almost no cherry leaf spot to speak of. Most of the blocks look very good to excellent. Blocks with the known high disease pressure should be considered for post harvest Bravo sprays to minimize the potential of outbreaks next year. There is some leaf spot on peaches, as well as symptoms of powdery mildew/rust spots. Insects continue with their activity. Codling moth has started the second generation. Across the board, it appears that the regional biofix could be set for July 14. Our trap count indicates accelerated activity of American plum borer. Lower numbers have been reported for lesser and greater peachtree borers, oriental fruit moth, obliquebanded leafroller, redbanded leafroller and cherry fruit fly. We did have our first apple maggot catch on July 19. Apple maggot is expected to start laying eggs in 7-10 days from the first catch or around July 26-30. |
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5 -- Northwest GDD42 2158 GDD50 1379 Weather No significant rainfall occurred in the past week. However, there were reports of hail in the Maple City and Old Mission areas. Crop report Growers in the Northwest are still harvesting tart cherries. Overall quality has been good, except where high winds resulted in some wind whip symptoms. Balatons are also approaching ripeness, and a few growers have begun to harvest these trees. Many post-harvest sprays have gone on in the past week. Early plums are ripe at the NWMHRS. Summer red raspberries are wrapping up in the area. No apple diseases have been observed at this time. Codling moth numbers remain low this week with only two moths per trap. Obliquebanded leafroller numbers are also low in apples at the NWMHRS, but we have observed hatches of small larvae in the past week in the terminals. Oriental fruit moth numbers are higher at the station this week, with over five per trap. Spotted tentiform leafminer numbers are through the roof. We caught our first apple maggot on sticky spheres this week at the NWMHRS; we had reports of maggot from scouts at the middle of last week. Still no disease in cherries unless you really look hard. When we have, we can see a bit of brown rot and cherry leaf spot, but your eyes are usually tired out by then! Powdery mildew is still prevalent in most orchards. Insect numbers are low overall, except for greater and less peach tree borers whose numbers rose from last week (16 per trap and 31 per trap). We have had reports of obliquebanded leafroller larvae during the harvest of tart cherries. |
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| Weather news Jeff Andresen An upper air ridging feature anchored across the Great Plains region led to yet another abnormally dry week across most of Michigan and the Great Lakes Region (some lucky areas did receive significant rainfall, but were the exception). Since the end of the first week in June, precipitation deficits have grown in many areas to the 2-4 inch range, which unfortunately has also coincided with periods of greatest seasonal plant water needs. The lack of water is currently most acute across southern and interior sections of northern Lower Michigan, and across western and central sections of the Upper Peninsula. In general, weather forecast guidance for the next couple of weeks does not suggest any major changes that would lead to meaningful relief from the dryness. A weak upper air trough will move from the upper Ohio Valley into southern Lower Michigan by Thursday, bringing the chance for a few showers or thundershowers. Because moisture with this system is lacking, any rainfall through Thursday is expected to remain light (less than 0.25 inch) and only scattered in terms of areal coverage. Further ahead, a cool front is forecast to move through the state Friday, which will bring the best chances for rainfall during the upcoming week. Showers and thunderstorms will be possible in northwestern sections of the state overnight Thursday, and across the Lower Peninsula on Friday. Fair, dry, and slightly cooler weather is likely during the upcoming weekend into early next week. Temperatures are expected to remain close to seasonal normals during the next few days, with highs ranging from the upper 70's north to mid 80's south and low temperatures from the upper 50's north to low 60's south through Friday. Temperatures will fall back a degree or two following the passage of the cold front Saturday. Next week, a broad ridging jet stream pattern is projected across the Upper Midwest, which will likely lead to a return of warmer than normal temperatures. Both 6-10 day and 8-14 day outlooks, covering July 29 through August 2 and July 31 through August 6, call for above normal temperatures. Unfortunately, the outlooks also call for normal to below normal precipitation totals during both time frames. |
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