East Michigan fruit update – Aug. 4, 2020

Much needed rain finally arrived for most of east Michigan in the past week. Blueberry and early peach harvest continue across the region.

Weather

Most growers have received three to four much-needed rain events in the past week. Precipitation totals generally ranged between 1 and 2.5 inches. Several of these rain events were long and steady rains that will penetrate deeply into the soil. However, for the very southeast tip of Michigan, they received only 0.24 inches of rain over two events. Drought conditions remain for these growers but for most growers, drought conditions have eased.

For most of our region, our season is still three to seven days ahead of normal for growing degree days (GDD) and three to five days ahead of fruit crop growth stages.

East Michigan growing degree day (GDD) totals for March 1 to Aug. 3, 2020

Location

GDD42

GDD45

GDD50

Commerce (Oakland County)

2541

2207

1702

Deerfield (Monroe County)

2749

2398

1869

Emmett (St Clair County)

2475

2143

1646

Flint (Genesee County)

2700

2355

1832

Freeland (Saginaw County)

2511

2180

1680

Lapeer (Lapeer County)

2497

2163

1657

Pigeon (Huron County)

2419

2099

1623

Romeo (Macomb County)

2578

2241

1731

Tree fruits

Apples have continued to size. Most apple fruit are 2 inches in diameter with Honeycrisp being 2.25 to 2.5 inches, with some well-thinned Honeycrisp blocks having fruit at 2.75 inches. Jersey Mac harvest is about a week to 10 days from harvest. Harvest of a few summer apple varieties continues. Hand thinning continues for many apple varieties.

For the second week, there are no new insect pests to report in apples, but there are several developments on insects we have already seen this season. Apple maggot and codling moth trap catch has remained strong over the last week. Keep covered for both of these pests. Woolly apple aphid numbers are climbing in some blocks; growers are finding clumps of woolly apple aphids on terminal branches. I am finding a few apple blocks with fruit feeding damage from rosy apple aphids. More growers are finding light amounts of San Jose scale damage on fruit. Now is the time to keep good records of where these are being found to target oil applications next spring.

Twospotted spider mite populations continue to build, mainly along fence rows and close to woodlots. Apple rust mite and European red mite populations are continuing to slowly build as well. Some limited bronzing of leaves from all three of these insects is being seen. Most blocks are still below threshold numbers, and predators are building in numbers to help control them.

Japanese beetle populations have declined again this week. I have not seen any brown marmorated stink bug insects or feeding damage in apples, but be on the lookout for them or their feeding damage. Beneficial or predator numbers continue to build. New this week is finding red velvet mites for the first time. Lacewing eggs and adults, lady beetle adults and minute pirate bugs continue to be seen.

I am starting to see in just a few apple blocks the beginnings of pinhead apple scab on fruit and sheet scab on leaves. Sooty blotch and fly speck symptoms were first reported two weeks ago, and more growers are finding light symptoms this week. Black rot fruit infections are even more common this week.

Lastly on apples, bird feeding or pecking damage is being seen at more farms. I am uncertain of the particular bird species doing damage, as I have only observed the damage.

Pears are mostly 2 to 2.25 inches in diameter. Pear size should be good this year. We are about four weeks away from the beginning of Bartlet harvest.

Peach harvest continues for early varieties. Red Haven harvest is expected to begin in seven to 10 days. Fruit coloring is continuing this week. Most mid-season peach varieties are between 2 and 2.5 inches in diameter. I am concerned that peach size development has stalled for many growers. The result may be too many small sized peaches this season. Peach size in the Romeo, Michigan, area is better than other regions.

Again this week I have found a few peach blocks with just a few late stages of brown marmorated stink bug nymphs or very young adults. I did not find any feeding damage. We have been catching just a few brown marmorated stink bugs in traps this week. Japanese beetle populations have declined over the past two weeks. Rusty spot continues to show up on some early peach varieties, however in very light amounts.

Sweet cherry leaf spot disease symptoms and leaf drop are slowing where post-harvest fungicide applications have been made.

Tart cherry leaf spot disease symptoms and leaf drop is less common than on sweets. Where post-harvest fungicide applications have been made, symptoms have been reduced.

Plums are mostly 1.125 inches in diameter for European varieties, with coloring continuing to develop. Japanese varieties are continuing with harvest. Most plum blocks have a poor crop due to freeze/frost damage.

Small fruits

Strawberry regrowth has rebounded well in most renovated fields this past week, most likely from recent rain events. Growers with dry soils are continuing to irrigate both renovated fields and new plantings. Newly planted strawberry rows are filling out nicely at most farms. Potato leafhopper leaf cupping damage is common in newly planted strawberries.

Raspberry growth has responded well to recent rain events in the past week for fall raspberries. Fall red raspberry fruitlets continue to develop. Blackberry flowering and fruitlet growth continues.

Blueberry harvest continues on many varieties. Berry size is starting to diminish on mid-season varieties. The largest berries are 12 to 15 millimeters in diameter. Remaining berries are coloring well. Spotted wing Drosophila (SWD) trap catch started across the region seven weeks ago, and again this week trap catches remain low in blueberries. Regardless of this low trap catch, SWD protection programs need to be ongoing in blueberries. Blueberry maggot trap catch has continued for the third week in a row.

Grapes are at berry touch for all varieties. Japanese beetle populations have declined for the second week in a row. The third generation of grape berry moth is just starting. Control measures will need to start soon. Downy mildew is a new pest to report in grapes this week.

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