East Michigan fruit update – Sept. 2, 2020

Much needed rain moved over the region in the past week. Apple harvest for fall varieties has started. Brown marmorated stink bug feeding damage in apples is more common.

Weather

Precipitation from several thundershowers brought between 1 and 3 inches of much needed rain over most of the region. Rainfall totals varied greatly over short distances. Most of the region saw strong winds embedded in these thunderstorm events. A few growers reported very strong microbursts with winds in the 50 to 60 mph range, resulting in some good amount of fruit drop and trellis systems leaning over to 45 or more degrees. A few trees have snapped off at the graft union. I have heard of a few orchards north of the Flint, Michigan, area that received 1-inch hail in the thunderstorms of last week.

Fruit crops are showing reduced signs of drought stress this week. There is little to no moisture deeper in the soil profile, however. Some forest and ornamental species of trees have seen excessive leaf drop in the last few weeks due to drought stress.

For all of our region, our season has moved back a few days this week to being seven to 12 days ahead of normal for growing degree day totals and remains a few days ahead of normal for fruit crop growth stages and beginning of harvest.

Yellowjackets have become a major pest this past week around farm markets and stands.

East Michigan growing degree day (GDD) totals for March 1 to Sept. 1, 2020

Location

GDD42

GDD45

GDD50

Commerce (Oakland County)

3365

2945

2295

Deerfield (Monroe County)

3604

3166

2492

Emmett (St Clair County)

3265

2846

2206

Flint (Genesee County)

3566

3134

2465

Freeland (Saginaw County)

3351

2933

2289

Lapeer (Lapeer County)

3285

2864

2213

Pigeon (Huron County)

3230

2823

2202

Romeo (Macomb County)

2425

3000

2345

Tree fruits

Apple size has increased by 0.25 to 0.375 inches in the last week, mainly due to recent rainfall. For growers that have been irrigating on a regular basis over summer, most fruit are 3 to 3.5 inches in diameter. For growers not able to irrigate, fruit size has picked up in the past week to 2.5 to 2.75 inches in diameter. Many apple varieties are coloring very well this season.

Gala harvest started in the last day or so at many farms to the south. On Monday, Aug. 31, I took my first set of samples for the apple maturity project. See “East Michigan apple maturity report – Sept. 2, 2020” for more details on apple harvest.

Bird feeding damage continues to be seen, especially from crows in Honeycrisp. Growers are setting bins in many blocks.

Brown marmorated stink bug (BMSB) feeding damage in apples is more common again this week than last. This feeding damage is light and isolated in scope, and trap catches have remained low in most blocks. Feeding damage can occur on any variety of apples but is more common and easier to see on light skinned apple varieties, such as Golden Delicious. I am also finding late BMSB instar nymphs and adults in apple and peach blocks. Most of the apple feeding damage is being found on orchard edges and along fence rows and woodlots. Growers with known hot spots for damage in previous seasons are treating these spots with a border application of an insecticide targeting BMSB. Consult the Michigan Fruit Management Guide (E-154) for specific control recommendations.

The drought conditions that we have been experiencing may be creating conditions conducive to BMSB movement from field crops and woodlots into orchards. BMSB damage can occur between now and the end of harvest. As I shared in my report last week, BMSB movement into apple blocks is unpredictable, so scout for this pest every few days. This is hard insect to scout for and to prevent damage.

Last week I shared that if nighttime temperatures remained high that we might have a third generation of codling moth. However, with the low nighttime temperatures of the last week and looking forward to the predicted low temperatures for the next few weeks, I don’t think this will be a problem this season. Woolly apple aphid numbers have continued to climb in many apple blocks; growers are finding clumps of woolly apple aphids on terminal branches. More growers are finding increasing amounts of San Jose scale damage in many apple blocks. As growers are harvesting apples this fall, it is a good time to keep records of where this damage is being found to target oil applications next spring. Beneficial numbers continue to slowly build.

Black rot and bitter rot fruit infection symptoms are being seen in more and more apple blocks. Some growers are removing this fruit in high value blocks, like Honeycrisp. Sooty blotch and fly speck symptoms are being seen by more growers, but it is fairly light this season compared to most seasons.

Pears are mostly 2.5 inches in diameter. Bartlet harvest began at some orchards last week and will be wrapping up in the next few days for other farms.

Peach harvest has ended for most farms or will be wrapping up harvest for the last picking of Canadian Harmony and Crest Haven in the next few days.

Sweet cherry leaf yellowing and drop has slowed in most blocks.

Tart cherry leaf yellowing and drop has slowed in most blocks.

Plums have colored well this past week. Stanley variety of European plum is expected to begin later this week. Most plum blocks have a poor crop due to freeze/frost damage.

Small fruits

Strawberry regrowth has continued to rebound in renovated fields. Newly planted strawberry rows continue to fill out well. The window is now open for another herbicide application in renovated fields.

Raspberry harvest for fall red raspberries continues, however the early pickings have been light compared to most years. Growth or overall length of fall raspberry canes has been much less than in most seasons, mainly from a combination or drought early this spring and too much heat this summer. Blackberry harvest continues.

Spotted wing Drosophila (SWD) trap catch has taken another jump this week. SWD protection programs need to be ongoing in fall red raspberries.

Blueberry harvest has wrapped up for most farms.

Grape clusters are filling out nicely and veraison has started in most varieties. Yellowjacket feeding has become a major problem in the past week. Downy mildew symptoms continue to be found.

Saskatoon leaf yellowing and drop continues on leaves that were fed on by Japanese beetle earlier in the season. It is too late for control measures at this time, as the damage has already occurred.

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