East Michigan fruit update – Sept. 19, 2018

Brown marmorated stink bug trap catches have taken a sharp rise at some east Michigan farms. Apple and fall red raspberry harvest are in full swing.


With continued hot day time temperatures and warm morning lows, our seasonal degree-day totals are 14 to 18 days ahead of normal. The peak harvest dates of some of our apple varieties has been a few days ahead of normal, and yet for others it is behind normal. This season has been a tough one to figure out.

Most areas of east Michigan have had good rainfall over the last month, bringing our seasonal totals back to normal to above normal levels. There are still some small isolated pockets of the region that have not had good rainfall events since early to mid-June.

Tree fruits

Apple harvest is moving along at full speed across the region. Honeycrisp harvest is almost complete, with a good amount of fruit drop over this past weekend. Harvest of McIntosh, Jonagold and some Jonathan blocks is underway. Keep a close eye on early maturing strains and sites of Golden Delicious and Red Delicious.

Brown marmorated stink bug (BMSB) trap catch has taken a big jump since late last week at about a fifth of the farms we have been trapping at all summer long. I have also seen adults and nymphs in the foliage and feeding on apples. Trap catch numbers have been in the range of 40 to 50 per trap. For the rest of the trapping sites, BMSB numbers have continued to rise slowly but steadily for the last month. Adults and young nymphs are being caught in traps. Since harvest has started, apple growers are finding some limited BMSB feeding damage to fruit in the bin as it is being brought from the orchard, sorted and graded. It has been very hard to find this damage in the orchard prior to harvest. Most of this feeding damage is four to six weeks old.

At farms with these high BMSB trap catch numbers, consider making an insecticide application to protect fruit from feeding injury. This is a challenging thing during harvest, with long pre-harvest intervals for most products and worker protection requirements. For the rest of the 80 percent of growers who have not seen high trap catch yet at their farm, keep checking traps every few days to see if numbers begin to spike. For growers not trapping for BMSB, scout for BMSB as you and your harvest crews are in the orchard to keep a close eye out for them.

Woolly apple aphid populations have been building on terminal branches over the last month in a many apple blocks. San Jose scale egglaying scars are being found at many farms as fruit is being harvested. Control of both of these pests is not practical at this time of the season, but will need some targeted attention next season. Keep an eye out for both of these pests as harvest continues.

Sooty blotch and flyspeck are being seen on fruit in many apple blocks over the last two weeks or so. Black rot symptoms on fruit are being found on several varieties at some farms, mostly on Honeycrisp. A few more “waves” of leaf yellowing and drop have been seen on Golden Delicious and related strains from necrotic leaf blotch. Many unsprayed apple and crabapple trees are experiencing extensive leaf yellowing and drop caused by apple scab. Watching these trees can give you an idea of pest pressure for next season, and even the possibility of pin head scab developing in stored fruit this fall.

Sweet and tart cherry growers have continued seeing leaf yellowing and drop, which has been found mostly where soils have been dry this summer. Most of this leaf damage was caused by a combination of drought stress and cherry leaf spot disease.

Small fruits

Strawberries continue to look good for most growers now that good rainfall has been received over the last month or so. The rows in renovated fields have filling in nicely and new plantings continue to runner well. Some new plantings continue to have high populations of potato leafhopper.

Raspberry harvest continues on fall bearing red raspberries. Spotted wing Drosophila (SWD) populations continue to build in fall raspberries and will continue to rise throughout the fall. Be watchful that covers for control for SWD are being made on a five-to-seven-day basis, and more often after rain events.

Grape harvest of Concord types is taking place as well as some early maturing wine grape varieties. Downy and powdery mildew symptoms have been commonly seen on leaves across the region.

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