Southwest Michigan fruit update – July 6, 2021

Michael Reinke<reinkem3@msu.edu>, Mark Longstroth<reinkem3@msu.edu> and William Shane<shane@msu.edu>, Michigan State University Extension - July 07, 2021

Summer fruit harvest is underway for berries and tree fruit.

Peaches on a tree. — Early peach varieties are beginning to color. Some are beginning harvest now. Photo by Mike Reinke, MSU Extension.

Weather

Scattered rain early last week resulted in half an inch to an inch and a half of rain for the region. The week started warm with highs in the 80s, cooling to 70 degrees Fahrenheit to start the weekend. By Monday, the high was back up to near 90 F for much of the region.

This coming week will see slightly lower temperatures with highs in the upper 70s for the week. Lows will be near 60. The best chance of rain will be on Thursday.

Soils still have some moisture from all the rain in the last two weeks. This soil moisture has come at the right time. Plants are fully leafed out and July and August are when plants use the most water.

With the warmer week, we picked up a number of growing degree days (GDD) last week: 202 GDD base 42 and 146 GDD base 50.

Southwest Michigan GDD summary from March 1 - July 4, 2021
Station	GDD 42 F	GDD 45 F	GDD 50 F
Benton Harbor (SWMREC)	1888	1619	1225
Lawton (Lawton)	1911	1640	1234
Fennville (TNRC)	1693	1438	1067
Average for the SW region	1863	1596	1201
Average last week	1661	1415	1055

Tree fruit

Resumption of dry and hot conditions has put water stress on young trees. San Jose scale males began showing up in the Trevor Nichols Research Center trapline on May 24 (biofix). San Jose scale control in the summer is focused on crawler control. Crawlers emerge about 400 GDD base 51 F after biofix, which is occurring now in much of the region. Japanese beetles are continuing to emerge.

Apricot harvest continues in the area. Ripening fruit has increased susceptibility to brown rot.

Apricot tree — Apricot harvest has begun. This is when they are most susceptible to brown rot. Photo by Mike Reinke, MSU Extension.

Early season peach and nectarine varieties Desiree, Earlystar and PF Early Eight Ball are developing red blush. Varieties prone to bacterial spot are developing yellow leaf tips. The most common insect problems affecting fruit now are oriental fruit moth and tarnished plant bug. Fruit turning from green to yellow/red and with insect injury have increased susceptibility to brown rot.

In cherries, sweet cherry harvest is ending. Tart cherries are now being harvested. Some wind whip damage from recent rains is present on some fruit. Spotted wing Drosophila (SWD) catches continue to be low but should increase soon. The low numbers are probably due to the hot, dry spring. With the wet conditions of the last couple weeks and abundant wild ripe berries, we expect numbers to increase in the next week or two. Cooler weather will also increase SWD numbers. Late harvested tart cherry blocks may need protection.

Since the early spring was so dry, cherry leaf spot symptoms are scarce for this time of year, but recent rains have been very favorable for infection.

In plums, early season plumcot (a plum-apricot hybrid) variety Spring Satin will be ripe within a week, with Early Golden and Methley following soon after. Plums are generally not susceptible to SWD until the fruit are noticeably soft.

Apple fire blight symptoms are still relatively rare. Sufficient wetting has occurred to increase the risk of sooty blotch and flyspeck infection on fruit. Codling moth, obliquebanded leafroller and oriental fruit moth flights and mating are continuing. Codling moth entries are becoming easier to see as the larvae get larger and push more frass out. The Trevor Nichols Research Center has reported catching apple maggot at low levels in the past two weeks.

Apples on a tree. — Apples are sizing up quickly. Apple maggot are now being caught. Monitoring is important for accurate management of this pest. Photo by Mike Reinke, MSU Extension.

Small fruit

Grape fruit size is increasing. Labrusca grapes are nearing bunch closure. Many hybrid wine grapes are already at berry touch or bunch closure. Vinifera grapes are at buckshot berry to berry touch, depending on variety and site. May 25-27 can be used as general dates for wild grape bloom in southwest Michigan. This is used for determining grape berry moth biofix. According to the grape berry moth model on Enviroweather, egglaying of the second generation should have begun between June 30 and July 3, depending on location. There were several disease infection events with the recent storms.

Protectant fungicide sprays to control Phomopsis, black rot, downy mildew and powdery mildew are the management focus for the month after bloom. Anthracnose has also recently been found. Wine grape growers will also want to include botrytis in their disease management plans.

Japanese beetle on leaf. — Japanese beetles are emerging. They are generally not as big a problem as they were years ago but can still cause sporadic problems. Photo by Mike Reinke, MSU Extension.

Blueberry harvest has begun. With all this rain, disease control should focus on protecting green fruit from anthracnose and alternaria. Wet fields are making spraying difficult, and many growers are using aircraft to get their sprays on. SWD numbers have been very low across the region. This is probably due to the hot, dry conditions in May and early June. With cool wet weather and the ripening of wild berries such as bush honeysuckle and black raspberry, growers can expect to see increased numbers in about a week.

Michigan State University is participating in a USDA-funded survey asking blueberry growers about their pollination practices. If you can, please take a few minutes to fill out the survey.

Strawberry harvest has ended. Renovation should begin as soon as you can work in the field.

Raspberry harvest has begun in Berrien County, with the harvest of both red and black raspberries. Blackberry bloom is ending. Fruit is sizing and coloring. SWD larvae were found in unsprayed backyard fruit last Friday. Raspberries are very attractive to SWD, and we expect number to increase in the next week.

Blackberries ready for harvest. — Raspberries are being harvested. Some blackberries, like those here, are starting to color. Harvest will begin soon. At this time, spotted wing Drosophila populations are low but are expected to increase soon. Photo by Mike Reinke, MSU Extension.

Miscellaneous crops

Chestnut bloom is continuing.

Hazelnut bloom has begun.

Currant harvest is beginning.

Cranberry bloom is ending.

Upcoming meetings

Viticulture Field Day will be returning to an in-person event this year. The event location is 12 Corners Winery on July 28. This will be an all-day event beginning at 9 a.m. The traditional steak dinner and wine tasting will return. There will be limited attendance. Pre-registration is highly recommended.

This article was published by Michigan State University Extension. For more information, visit https://extension.msu.edu. To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters. To contact an expert in your area, visit https://extension.msu.edu/experts, or call 888-MSUE4MI (888-678-3464).