Southwest Michigan fruit update – June 14, 2022

Michael Reinke<reinkem3@msu.edu>, William Shane<shane@msu.edu> and Cheyenne Sloan<sloanche@msu.edu>, Michigan State University Extension - June 14, 2022

Cherries are beginning to color up. Harvest is just around the corner.

Sweet cherries. — Sweet cherry harvest will begin soon. The fruit are coloring up and softening. Some growers were putting on anti-crack sprays ahead of yesterday’s rain. Photo by Mike Reinke, MSU Extension.

Weather

Last week started cool. High temperatures on Tuesday and Wednesday were in the 60s. Temperatures slowly increased through the rest of the week and weekend with highs in the upper 70s by Sunday. A dome of high pressure entered the state on Monday bringing heat. Highs on Monday were in the mid to upper 80s. A warm front moved into southwest Michigan Monday evening bring more heat for the next couple days.

The cool start to the week was also a rainy one. Many areas saw rain on Monday, Tuesday and Wednesday with total amounts near an inch. A line of severe storms moved through southwest Michigan yesterday with high wind and rain amounts at Enviroweather stations recording a half to 1 inch and growers reporting up to 2 inches. Hail damage was reported for Cass County.

Damage to Concord grapes. — Yesterday’s storms were severe, but localized. Some growers are reporting damage. Here is concord juice grape with hail and wind damage from yesterday. Photo by anonymous grower.

This week will be hot. High temperatures on Tuesday will be in the upper 90s. Not much cooler Wednesday and Thursday. Friday will see a return to normal temperatures for the weekend. No significant rain is predicted the rest of the week.

With the cooler week, we picked up fewer degree days,149 growing degree days (GDD) base 42, 96 GDD base 50.

Southwest Michigan GDD summary from March 1 through June 13, 2022
Station	GDD 42 F	GDD 45 F	GDD 50 F
Benton Harbor (SWMREC)	1190	989	695
Lawton (Lawton)	1188	990	699
Fennville (TNRC)	1083	891	612
Average for the SW region	1174	976	689
Average last week	1025	848	593

Tree fruit

Tree fruit crops are finishing their natural June drop. With the sunny weather and high evapotranspiration rates this past week, trees in drought prone areas may start showing stress as the soils continue to dry out. Light colored foliage due to nitrogen deficiency is becoming noticeable as plant reserves are being used up.

Newly planted trees may have bloom, which are attractive to bees and other pollinators. Be cautious with sprays, avoiding when possible, and spraying at night when necessary to avoid harming pollinators.

Estimated emergence of San Jose scale crawlers is 400 to 450 degree days base 51 after the biofix. The biofix was the start of male flight biofix on May 16, 2022, according to the Trevor Nichols Research Center trapline. With the heat upon us, emergence should begin this week throughout southwest Michigan. Management of first generation will reduce damage later in the season.

Codling moth, oriental fruit moth, and obliquebanded leafroller are all being caught in traps. Codling moth egg laying has been for a couple weeks. Obliquebanded leafroller and second generation oriental fruit moth flights have begun in the last week or so. Egg laying will begin later this week.

Apricot crop is generally light, but better than last year. Some bacterial spot symptoms have been showing up.

Peach and nectarine fruit size is approximately 35 mm diameter for Red Haven in central Berrien County. Pit hardening is still a week or two off. June drop is reducing crop below a full load in some sites. Hand thinning has begun. Estimated harvest date for Redhaven for Berrien County is Aug. 1, about average. Crop potential is for the area is still decent to good. Oxytetracycline should be used instead of copper for bacterial spot to reduce chances of phytotoxicity. Rusty spot management is needed until pit hardening for susceptible peach varieties. Peach scab management is needed now. Both lesser and greater peach tree borer adults are flying. Pheromone disruption for these two pests, if being used, should be in place as soon as practical. There are trunk spray chemical options beyond chlorpyrifos, but read labels carefully when choosing.

Oriental fruit moth damage. — Oriental fruit moth damage is showing up. This time of year, most damage is on the terminal shoots of stone fruits. This flagging is a result of an oriental fruit moth larva burrowing in and feeding on the new shoot. Photo by Bill Shane, MSU Extension.

In cherries, tart cherries are straw colored with blush starting to show up. Sweet cherries are coloring up and softening ahead of harvest. Both crops look generally good for SW Michigan with some exceptions for some locations that saw an impact from early April cold spells and poor pollination conditions. ProGibb treatment for suppression of bloom on young trees generally starts about 3 weeks after bloom. Cherry leaf spot control should continue. The EnviroWeather station in Bainbridge township of Berrien County has recorded 8 cherry leaf spot infection periods since late April, two more than in 2021 at this same time.

In plums, crop potential is generally better for Japanese plums than for European types. Japanese plums are up to 25 mm and European plums are mainly around 22-23mm. Continue black knot management on susceptible cultivars until terminal growth is generally halted. Watersoaked bacterial spot symptoms are starting to show up on fruit. Internal worms, either 1^st generation codling moth or oriental fruit moth, are showing up in a few sites.

Apple varieties range from 32 to 37mm in diameter. Seeds and surrounding core flesh are turning brown in fruit that will drop. The primary apple scab spore release period appears to be nearly over. More reports of fire blight symptoms are showing up, but the general level is relatively low. Symptoms trace back to blossom infections. Tarnished plant bug and green fruitworm damage has been seen in the area. Tarnished plant bug becomes active when we see temperatures above 70. Treatments after bloom are typically common for this pest. Codling moth egg hatch is likely underway. Egg hatch is when treatments typically start for this pest.

Pears are at 23 to 28mm in diameter. Pear psylla adults are present in some blocks. Powdery mildew symptoms are present on terminal foliage of pears. This is the same strain commonly found on apples, but rarely on pears.

Small fruit

Grapes: Juice grapes are beginning to shatter. Some vinifera and many hybrid wine varieties are blooming. Marquette and Brianna varieties are finished blooming and fruit are near buckshot berries. Disease management of phomopsis, black rot, downy and powdery mildews are the primary focus currently. In wine grapes, materials to control botrytis should be included in the sprays. Downy mildew and phomopsis damage is being seen. Some growers have begun weed sprays.

Blueberry fruit are 10-13mm. Fruit set looks good in many locations. Disease focus should be on early fruit rot management. Cranberry fruitworm are being caught in pheromone traps. Cherry fruitworm moth catch is expected as well. According to Enviroweather, egg laying should be underway for both species. Fruit are required for egg laying and damage, so management usually begins after fruit set when egg laying begins. Second applications of fertilizer are wrapping up and weed control sprays are continuing.

Blueberry mosaic virus. — Blueberry mosaic virus causes splotchy yellow or pink patterning on the leaves. Here is Bluecrop blueberry with mosaic virus. It is not noticeable every year. The only way to get rid of it is to remove the plants. Photo by Cheyenne Sloan, MSU Extension.

Strawberry harvest continues. Maintain fungicide coverage to protect the leaves and help prevent fruit rots as fruit continue to ripen, especially with the heat and afternoon rain chances this week. The heat, humidity and especially yesterday’s storms may shorten the season for some growers. Slugs have been reported in some fields.

Anthracnose in strawberries. — Anthracnose is being seen in strawberries. With the warm humid weather, fungicide coverage is critical to protect the fruit from this and other ripe rots. Photo by Cheyenne Sloan, MSU Extension.

Bramble bloom is ending in raspberries and blackberries. Raspberry sawfly scouting should continue. This insect eats leaf tissue between the veins giving them a skeleton-like appearance.

Cranberries have greened up. Upright growth has begun, and flowers are visible as hooks. Bloom should begin soon with the hot weather this week.

Hops growth continues with some varieties 2-4 feet from the top. Downy mildew spikes have been a problem in susceptible varieties this year. Early season management is important to stay ahead of this disease in hops. European corn borer has been flying for a couple of weeks, but very few have been found during scouting of hopyards this year.

Upcoming meetings

Our regular Southwest Michigan Monday Fruit IPM Updates has moved to a hybrid format. The meetings are being held in person with virtual attending also available online. Our meetings are on Mondays beginning at 5:30 p.m. You do need to register to receive the Zoom link and password for these meetings. A link is emailed each Monday morning for that evening’s update. The webinars are free of charge and two pesticide applicator credits and certified crop advisor credits are available for each meeting.

The Southwest Michigan Viticulture Field Day will return to the Southwest Michigan Research and Extension Center for 2022. As tradition holds, the event will be the last Wednesday of July (July 27) and include presentations of ongoing research in southwest Michigan. The event will once again conclude with a steak dinner and local wine tasting. Registration information to come soon.

This work is supported by the Crop Protection and Pest Management Program [grant no 2021-70006-35450] from the USDA National Institute of Food and Agriculture.

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).