East Michigan fruit update – Sept. 16, 2020

Apple harvest is in full swing. Gala harvest is nearly complete with Honeycrisp and McIntosh harvest continuing. More rains have finally come to the region over the last two weeks.

Bitter pit symptoms in apple
Bitter pit symptoms in apple. Photo by Bob Tritten, MSU Extension.

Weather

Several rain events have come to the region over the last two weeks, bringing close to 1.5 inches of precipitation. Rainfall totals varied greatly over short distances. These rain events helped apples and fall red raspberries to size well. Fruit crops are showing reduced signs of drought stress over the last three weeks or so. Some forest and ornamental species of trees have seen excessive leaf drop in the last month due to drought stress.

For all our region, our season is still about seven to 12 days ahead of normal for growing degree day (GDD) totals and remains a few days ahead of normal for fruit crop growth stages and beginning of harvest. Yellowjackets continue to be a pest around farm markets and farm stands over the last three weeks or so.

East Michigan growing degree day (GDD) totals for March 1 to Sept. 15, 2020

Location

GDD42

GDD45

GDD50

Commerce (Oakland County)

3625

3163

2445

Deerfield (Monroe County)

3902

3421

2680

Emmett (St Clair County)

3506

3046

2340

Flint (Genesee County)

3840

3366

2628

Freeland (Saginaw County)

3589

3138

2427

Lapeer (Lapeer County)

3531

3068

2352

Pigeon (Huron County)

3486

3038

2349

Romeo (Macomb County)

3689

3223

2499

Tree fruits

Apples have sized and colored well over the last two weeks. Gala harvest is nearly complete, with McIntosh and Honeycrisp harvest taking place. As growers have started harvest, they are finding bins are filling faster than expected.

I have several late season apple pests to share today. The first is brown marmorated stink bug (BMSB). With the exception of a few isolated hot spots for this pest, trap catches have remained low this week in most blocks. Feeding damage has also been light and isolated in scope. 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 and Crispin. I am finding late BMSB instar nymphs and adults in apple blocks, but with little feeding damage. Where I am finding damage, it is mostly 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 State University Extension Michigan Fruit Management Guide (E-154) for specific control recommendations.

The drought conditions we have been experiencing this summer may be creating conditions conducive to BMSB movement from field crops and woodlots into orchards. Soybeans are also drying down; this may lead to movement into apple blocks. BMSB damage can occur between now and the end of harvest. BMSB movement into apple blocks is unpredictable, so scout for this pest every few days. This is a hard insect to scout for and prevent damage.

Woolly apple aphid numbers have continued to climb in many apple varieties and blocks. Growers are finding clumps of woolly apple aphids on terminal branches. Their honeydew can spoil apple finish and annoy harvesting crews. This is making for tough harvesting by pickers. If management is needed, Movento and Closer SC are both excellent aphid products with short, seven-day preharvest intervals. At this late date, control measures are tough because of preharvest intervals.

San Jose scale damage is showing up as blocks are being harvested. 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.

Black rot and bitter rot fruit infection symptoms are being seen in more and more apple blocks. Some growers are removing this fruit prior to harvest in high value blocks, like Honeycrisp. A new problem being seen in the past week is bitter pit symptoms in Honeycrisp and Jonagold. As apple harvest continuers, growers are seeing more and more fire blight strikes. These infections appeared much later in the season than usual.

Lastly, as apple growers are continuing with harvest, many are finding more apple scab on fruit than they anticipated. Overall, given the high apple scab pressure of this season, most growers have done a good job of controlling scab. To get a sense of the high pressure from scab this season, keep an eye on ornamental crabapples, most have lost all of their leaves due to apple scab. So, my three conclusions from these observations are that it was a fairly tough apple scab season, there will be a good amount of pressure next season and most growers did a good job in controlling it this season.

Pear harvest is finished, except Anjou and Bosc.

Small fruits

Strawberry regrowth has continued to rebound in renovated fields. Most fields have filled the rows well with good, healthy crowns developing for next season. Newly planted strawberry rows have also filled in well, especially after recent rains.

Raspberry harvest for fall red raspberries continues, however pickings have been light compared to most years. Consumer demand for fall red raspberries has been exceptionally strong this fall. Spotted wing Drosophila (SWD) trap catch has continued to slowly build over summer and fall. SWD protection programs need to be ongoing in fall red raspberries.

Grape harvest has begun for several early fall varieties. Yellowjacket feeding has been a problem for many varieties.

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