East Michigan fruit regional report – August 2, 2016

Weekend precipitation came to a few farms, but drought conditions continue at most. Last week saw first trap catch of brown marmorated stink bug. Red Haven peach harvest started over the weekend for southern growers.

Weather

Several thunderstorms and rain patterns moved over the region last Thursday, July 28, and over the weekend, July 30-31. Precipitation totals from these events vary widely across the region, but the bottom line is that for most farms, it only brought a few tenths on an inch of rain, not enough to bring an end to drought conditions.

The range of total precipitation from these latest series of showers that I have heard from fruit growers is 0.01 to 7.25 inches. If I average the precipitation from these latest rains for the eight Michigan State University Enviro-weather stations that I track degree-day totals in most of these reports, we received an average of only 0.29 inch. So, while a few fruit farms did receive some significant rain over the last week, drought conditions continue for most farms.

Newly planted and now established tree and small fruits continue to show signs of wilting, and some plants have died as a result of lack of rainfall. Growers continue to devote a great deal of time to irrigation activities. Fruit size continues to be reduced for all of our fruit crops, mainly due to the drought.

Our degree-day totals have continued to build due to heat and we are at least a full week ahead of normal. In terms of the fruit crop growth stages and beginning of harvest, we are also running about a week ahead of normal.

East Michigan growing degree-day totals for March 1 to Aug. 1, 2016

Location

GDD42

GDD45

GDD50

Commerce (Oakland County)

2,544

2,198

1,677

Deerfield (Monroe County)

2,835

2,462

1,895

Emmett (St Clair County)

2,474

2,139

1,634

Flint (Genesee County)

2,735

2,384

1,853

Freeland (Saginaw County)

2,483

2,153

1,652

Lapeer (Lapeer County)

2,509

2,173

1,668

Pigeon (Huron County)

2,306

1,991

1,516

Romeo (Macomb County)

2,629

2,282

1,760

Tree fruits

Apples are mostly 2.375 to 2.75 inches in diameter for most growers. Where growers had a good amount of rain over the weekend, I am already seeing a nice bump in fruit size. Harvest of Williams Pride and other summer apple varieties continues. Paula Reds and McIntosh are coloring. Growers are hand-thinning high value apple varieties. Growers will begin Retain applications on Gala late this week and maybe some McIntosh next week. The first Retain applications can be made four weeks prior to harvest. Sunburn is being seen in a few early varieties. Some growers are reporting bird feeding injury in apples, most likely due to drought.

Brown marmorated stink bug trap catch occurred on one farm this past week, and it was just one adult. While this does not trigger an application of an insecticide for control, it is a signal that other growers should be scouting for this pest. You may find it feeding on fruit or on leaves and branches. Apple maggot catch on yellow sticky board traps has been strong on farms that had good amounts of rain in the past week, but at most farms where soils are very dry, apple maggot emergence seems to have been delayed. I have not heard of any trap catch on red sphere traps.

In the last few days, I am finally starting to see codling moth trap catch for the second generation adult flight; this is later than in most seasons. Woolly apple aphid populations are slowly declining in blocks where an insecticide application was made, however woolly numbers are building in untreated blocks, with many woolly apple aphids moving out to terminals and on to fruit. European red mite and twospotted spider mite numbers have increased in the past week, a few blocks are above threshold levels. Japanese beetle adult numbers are about the same as the last few weeks. Obliquebanded leafroller larvae are feeding on fruit, but generally in low numbers. Beneficial numbers continue to build, especially lacewings and assassin bugs.

More black rot symptoms are being found on fruit this week. Sooty blotch and flyspeck disease symptoms should be appearing soon.

Pears are mostly 2 to 2.25 inches in diameter. Pear fruit size is being affected by the drought. Pear psylla numbers are high on suckers.

Peaches are 2.5 to 3 inches in diameter for most growers. Red Haven harvest began over the weekend in the south and is expected to begin late this week at most other farms. I have not seen any brown rot symptoms, but for growers who received a good amount of rain this past week, you may consider a brown rot fungicide application fairly quickly.

Sweet cherry and tart cherry leaves are starting to yellow, most likely from cherry leaf spot symptoms.

Plums have colored for European types. Japanese varieties are being harvested. The crop load is variable for both types, especially in some Japanese varieties as they have little to no crop.

Small fruits

Grape growth continues to be slow; Concord fruit clusters are filling out and European varieties are at berry touch. Japanese beetle and rose chafer adults are being seen, but in very low numbers.

Strawberry leaves are regrowing in renovated fields where irrigation has been applied. MSU Extension encourages growers to keep new and established berries well-watered. New berries are runnering well and are filling the row at most farms. Potato leafhopper populations are building in new plantings. Growers should watch for curled leaves, although this symptom can be somewhat confusing as some of the same symptoms can be seen with drought stress.

Raspberry harvest is about over for summer red raspberry varieties. Blackberry harvest is continuing at most farms. For fall red raspberry growers, limited harvest of shorter canes continues. Fall red raspberry canes are shorter this season than most years, and are much shorter than last season’s unusually long canes.

Trap catch of spotted wing Drosophila (SWD) continued with another big jump across the region, from an average of just over 14 adults per trap last week to an average of nearly 50 SWD per trap this week. Growers need to protect red raspberries now for SWD infestation. For more details on the SWD life cycle, control strategies and specific insecticide recommendations, consult the MSU SWD website.

Blueberry harvest continues. Berry size is a problem at most farms, mostly due to drought. As in raspberries, this week trap catch of SWD in blueberries has taken another big jump across the region, from an average of just over 14 adults per trap last week to an average of nearly 50 adults per trap this week. Growers need to protect now for SWD infestation. For more details on SWD life cycle, control strategies and specific insecticide recommendations, consult the MSU SWD website

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