Southwest Michigan fruit update – Sept. 17, 2019

Brown marmorated stink bug numbers really jumped last week. This pest is on the move.

handful of brown marmorated stink bugs
A double handful of brown marmorated stink bugs were trapped last week in Berrien County by Mike Reinke. Photo by Mike Reinke, MSU Extension.


Last week was warmer and wetter, more like summer than fall. High temperatures climbed into the upper 80s by mid-week with lows in the 60s. Storms moved across the region and brought showers. Most of these storms came in the evenings and early mornings. Rainfall totals varied quite a bit as these storms dropped heavy rain (0.3 to 1 inch) in a short time in some areas but not others. Rainfall for the week ranged from 0.8 to 2.3 inches, averaging about 1.7 inches.

The potential evaporation was only about a third of an inch for the week. Most soils still fairly dry. We are seeing more colors as plants that lose their leaves early are shedding their leaves.

The forecast this week is for warm, summer-like weather with highs near 80 and lows around 60. Cooler weather and rain will return by the weekend. The warmer conditions increased heat accumulations.

Last week, we gained about 200 growing degree days (GGD) base 42 and 140 GDD base 50. The warmer conditions also seemed to ramp up insect activity.

Southwest Michigan GDD summary from March 1 – Sept. 15, 2019


GDD 42 F

GDD 45 F

GDD 50 F

Benton Harbor (SWMREC)




Lawton (Lawton)




Fennville (TNRC)




Average for the SW region




Check out the animated weather forecasts from Jeff Andresen at the weather tab in the Michigan State University Extension Fruit & Nuts Page. Please note there is no weather video for this week. Articles and other regional reports can be found at the Fruit News page.

Tree fruit

Many growers have treated for late season insect pests in the few weeks. We continue to catch late season fruit pests. The numbers are similar to last week’s catch. Oriental fruit moth trap catches are still high in some orchards. Codling moth trap catches are trending down. Catches of brown marmorated stink bug adults really jumped last week. Very high numbers of brown marmorated stink bugs were caught in traps that had caught only a few insects previously. This pest is moving into orchards. Brown marmorated stink bugs can cause significant damage late in the season.

Peach shoot tips are susceptible to oriental fruit moth if they are still growing, otherwise this pest is not an issue this late in the season in peaches.

In cherries, post-harvest chlorothalonil applications are wearing off and more orchards are beginning to lose their leaves to cherry leaf spot.

Plum harvest has ended.

Apple growers are picking Gala and Honeycrisp for the fresh market. Apples are also being harvested for processing. The cool weather has enhanced fruit color and bird pecks are a problem on red fruit. Apple maturity reports are released on Wednesdays and posted to the MSU Extension Fruit & Nut News Page.

Brown marmorated stink bug numbers really jumped last week. This pest is moving into the orchard to feed on fruit and this injury will show up at harvest. See the brown marmorated stink bug update for Sept. 13, 2019 for more information. Growers may need to apply sprays to prevent injury to later maturing apples. Codling moth, oriental fruit moth and obliquebanded leafroller are also threats to fruit now. Growers may need additional insecticides to be on the safe side with later maturing varieties.

Small fruit

cranberry fruit
Cranberries are hidden under upright shoots. Photo by Mark Longstroth, MSU Extension.

Spotted wing Drosophila numbers are probably high, but few people are still trapping this pest. Growers should protect ripening fruit.

Grapes are ripening. The harvest of Niagara grapes for juice will begin next week and Concord harvest is scheduled for early October. Downy mildew is still a concern if harvest is further than a few weeks away.

We are still catching grape berry moth, so egglaying continues. Many growers have applied insecticides recently to protect against fruit flies, wasps and berry moth to try and keep the fruit clusters clean and reduce bunch rots. Botrytis and sour bunch rot of the berry clusters are a concern—see “Late season cultural and chemical options for diseases in grapes—don’t wait!

Blueberry harvest is finished. Recent rains have relieved some drought stress. Soils should be kept moist in September. Fruit bud development is starting and expanding buds are visible. Drought conditions can reduce next year’s crop potential by reducing flower bud numbers. Some growers have begun to prune their bushes because harvest is over and they have labor. Fall pruning reduces the plants winter hardiness and can set up increased winter damage if we have another cold winter.

Strawberries are growing well. Fall harvest of day-neutral strawberries is underway. The June bearing fields need be irrigated to maintain good plant growth. Day neutrals are setting flower buds now for next spring. Include fungicides to protect the leaves from foliar diseases—see “Protect strawberries from foliar diseases after renovation.”

Fall raspberry harvest continues. Raspberries and blackberries are very attractive to SWD and fruit needs to be protected from this pest. One effective way to reduce SWD is to shorten the harvest interval to two days and pick all ripe fruit. Sort out the soft berries and destroy them away from the field. In summer raspberries, old floricanes should be removed to increase sunlight and air flow in the planting reducing disease.

Cranberry harvest is expected in early October.

This is our final crop update for the 2019 season.

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