East Michigan fruit update – Aug. 14, 2018

Most fruit growers from Flint northward through the Thumb received another inch of rain. Drought conditions continue for most growers to the south.


Most fruit growers received over an inch of precipitation along and north of the I-69 corridor. The majority of this rain came last Wednesday, Aug. 8, with scattered showers over several days. While this region is still short of precipitation for the season, most areas are now only around an inch below normal.

Growers to the south of the I-69 corridor did get some rain showers in the past week, however most are still 2 to 3 inches below normal rainfall for the season. Most of these growers are still irrigating on a regular basis, and signs of drought stress are common in tree and small fruits. A few unfortunate fruit growers have received less than half of an inch of rain since early June.

Our season continues to run 10 to 14 days ahead of normal in growing degree-day (GDD) totals and about five days ahead of normal in terms of the start of harvest for some of our summer fruit crops. Degree-day totals have continued to build rapidly with hot day time temperatures and warm morning lows.

East Michigan GDD totals for March 1 to Aug. 13, 2018





Commerce (Oakland County)




Deerfield (Monroe County)




Emmett (St Clair County)




Flint (Genesee County)




Freeland (Saginaw County)




Lapeer (Lapeer County)




Pigeon (Huron County)




Romeo (Macomb County)




Tree fruits

Apples have continued to size well on farms where irrigation has been applied throughout the season and on farms that have received good rainfall in the past two week. Apples have responded well and taken on a good swell in fruit size. For others who are still experiencing drought and without irrigation, fruit size has stalled over the last three weeks.

Where soil moisture has been adequate, Honeycrisp are mostly in the range of 2.5 to 3.0 inches in diameter, with most other varieties 2.25 to 2.625 inches in diameter.Gingergold harvest has started on some farms, Sunrise harvest has wrapped up. Some Paula Reds continue to see fruit drop, but most of the drop is from fruit pushing other fruit off the limb.

Application of harvest management aids, such as AVG (Retain, 1-MCP [Harvista]), has started on Gala and Honeycrisp. Growers are lining up applications on these and other varieties.

Most farms have had a drop in codling moth trap catch over the last week. However, there are a few farms where trap catch numbers remain high, in the range of 25 to 70 per trap. In these problem blocks, codling moth controls will need to be maintained for at least two more weeks. With the heat of the season, we might have a partial third generation of codling moth.

San Jose scale crawlers have emerged this week, so controls can go on in the next seven to 14 days in problem blocks. This is the last window of the season to control them. While green apple aphids are not a new pest, good numbers have been seen in the past week, mostly on farms that have seen good rainfall over the last few weeks.

Apple maggot trap catch has dropped off this week. European red mite populations have also dropped off this week, especially at farms that have received rain. Predators have also reduced their numbers.

Brown marmorated stink bug trap catch continues to rise at most trapping locations. I continue to see more limited and very scattered feeding damage in some apple blocks and varieties. For some unknown reason, most of the brown marmorated stink bug damage thus far this season has been seen in Gala blocks; most of the damage was found in Honeycrisp last season, and most damage was found in Golden Delicious and Northern Spy blocks in the season before. This is a hard pest to scout for at this time of the season, as many times we will find damage to fruit where traps are close by and yet no adult trap catch has been seen. Entomologists think the pheromone used to attract this pest does not work well in summer as it is an aggregation type of pheromone, and this pest does not start to aggregate until sometime in fall, maybe mid-to-late August.

I am finding good numbers of lacewing adults, lady bug adults and minute pirate bugs.

Black rot symptoms on fruit are being seen at more farms this week. Necrotic leaf blotch in Golden Delicious and related strains is more common this week as well. Leaf spotting and yellowing symptoms are appearing rapidly. Sooty blotch and fly speck symptoms are yet to be seen this season, but fungicide applications need to be made later this month to control it.

Pears are mostly 2.25 to 2.5 inches in diameter. All stages of pear psylla continue to be present in poorly managed blocks, especially in blocks where suckers have not been removed.

Peach harvest is underway for Red Haven and other main season varieties across the region. Where soil moisture has been in good supply, they took on a final swell and fruit size and overall quality is good. Most peaches on these sites are between 3.0 and 3.5 inches in diameter. On dry soil sites, fruit size is a problem. Also on these sites, leaves are curled and trees look tough. I hope they recover before the season ends, otherwise I am concerned about tree health and winter survival.

Brown marmorated stink bug trap catch continues to slowly rise in peaches. I have been in a number of peach blocks this week where brown marmorated stink bug feeding damage was found at harvest or during grading. The fruit damage is light and scattered. If you find suspected feeding damage or adults in peaches, contact me via email, at tritten@msu.edu.

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

Plum harvest continues for Japanese varieties, with most varieties having a short crop. European varieties have continued to color well as they move toward harvest. Here again, the crop load is generally light. Most Stanley types are 1.25 to 1.375 inches in diameter. Some blocks continue to have light amounts of bacterial spot infection on the fruit causing spotting.

Small fruits

Strawberries continue to rebound well from renovation, especially where irrigation has been applied and now that some growers have received good amounts of rainfall. Regrowth has not been so good where soils are dry. Many new plantings have now filled in the row with good runner development. Runners needed to be pulled in one last time.

Some new plantings continue to have high populations of potato leafhopper. Some hard-to-control weeds are growing well in renovated berries, especially white cockle and butter and eggs.

Raspberry harvest continues on fall bearing red raspberries and a few late season summer red raspberry varieties. Most plantings of fall raspberries have a big crop coming on, but the volume of ripe berries has been light thus far this season. Now is a critical time for moisture to size these growing fall raspberry fruitlets.

Spotted wing Drosophila (SWD) populations continue to build in fall raspberries as they begin harvest. In the past three weeks, I have seen the number of larvae in fruit take a dramatic climb. Be watchful that covers for SWD control are being made on a five- to seven-day basis, and more often after rain events.

Blueberry harvest is quickly moving along at most farms. At some farms, harvest will wrap up in a week or so. The further we get into blueberry harvest, the more issues growers are having maintaining berry size.

Spotted wing Drosophila (SWD) populations continue to build as we move through the season. In the past three weeks, I have seen the number of larvae in fruit take a dramatic climb. Be watchful that covers for SWD control are being made on a five- to seven-day basis, and more often after rain events. Trap catch of blueberry maggot has dropped off this past week.

Grape berry size and vine growth continues. Pruning of root suckers and branches in the lower part of the canopy continues.

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