Southwest Michigan fruit update – May 17, 2022

Michael Reinke<reinkem3@msu.edu>, William Shane and Cheyenne Sloan<sloanche@msu.edu>, Michigan State University Extension - May 17, 2022

Crop development was very fast last week. Tree fruit bloom is almost finished.

peach bloom — Peach bloom is finished. Early varieties are emerging from the shuck. Plum curculio damage has been seen in many blocks because of last week’s heat. Photo by Mike Reinke, MSU Extension.

Weather

Last week was hot. Southwest Michigan saw several days at or near record highs. Tuesday through Friday, high temperatures were near 90, lows in the upper 60s. The rest of the week was in the mid to upper 70s, still above average for this time of year. The only rain was recorded late Sunday and early Monday morning with totals near a tenth of an inch at most stations.

The coming week will not be as hot. The week will see highs in the upper 60s to mid 70s, rising to the low 80s at the end of this week before cooling back off for the weekend. Rain is forecast for Wednesday and again on Friday and Saturday.

With the hot week, we picked up a lot of degree days, 200 growing degree days (GDD) base 42, 144 GDD base 50. This is similar to warmer weeks we have seen in July and August in recent years. We collected almost 3 weeks of degree days in the past 7 days. We are almost caught up to the long-term average. The soils have also dried out and warmed up a lot in the past week.

Southwest Michigan GDD summary from March 1 through May 16, 2022
Station	GDD 42 F	GDD 45 F	GDD 50 F
Benton Harbor (SWMREC)	580	462	304
Lawton (Lawton)	574	458	304
Fennville (TNRC)	532	423	277
Average for the SW region	573	458	304
Average last week	373	279	160

GDD42 SWMREC 05152022 — Last week was warm enough to catch up on our degree day deficit. Last week we were 2 weeks behind. Today we are almost caught up.

Tree fruit

The hot week brought rapid development. Most tree fruits are finished or almost finished blooming. Even with bloom mostly finished, any remaining blossoms are attractive to bees and other pollinators. Be cautious with sprays, avoiding when possible, and spraying at night when necessary to avoid harming pollinators. Plum curculio sickle-blade-like damage has been seen on developing stone and pome fruit.

The Enviroweather biofixes for Oriental fruit moth and Codling moth have been met and are being caught in traps. Post bloom management of these moths is beginning this week.

Apricots are out of the shuck and at 15-18mm.

Peach and nectarine bloom is almost finished. Most fruit are in the shuck or emerging now. As fruit emerge from their shucks, switch away from copper to oxytetracycline to reduce chances of phytotoxicity. Rusty spot management is needed after shuck split for susceptible peach varieties. Peach leaf curl symptoms should be showing up soon.

In cherries, bloom is almost finished. Sweet cherries are at 12mm, tarts are up to 9.5mm diameter with some bloom still in some blocks. Recent rains have been cherry leaf spot infection periods helped along by warmer temperatures.

20220516_tart cherry — Tart cherry bloom is almost finished. Many fruit in Berrien County are 7-9 mm in size. They are big enough to be attacked by plum curculio. Photo by Mike Reinke, MSU Extension.

In plums, all varieties are coming out of the shuck. Many are still under 6mm. Continue black knot management on susceptible cultivars until terminal growth is generally halted.

Apple varieties are mostly at petal fall with some late blooming varieties still with significant bloom. Very early varieties are 10 to 12mm in diameter. Conditions were favorable for fire blight on Sunday and Monday. Scab sprays are needed during the primary scab season from March to early June to protect against ascospores released in rains. With warm temperatures and rain predicted this week, protectants are preferred over systemic fungicides at this time of year for scab control to reduce the number of systemic fungicide applications and thereby slow the development of resistance. Powdery mildew and rust control generally start at pink. Tarnished plant bug and green fruit worm damage has been seen in the area. This insect becomes active when we see temperatures above 70. Treatments after bloom are typically common for this pest. Codling moth biofix was likely last week or the start of this week for most areas. Treatments for this insect should begin in the next week.

Pear bloom is finished.

Small fruit

Grape have moved quickly in the recent hot weather. Concord and Niagara are at 8 inches of growth in Berrien County, 6 inches in Van Buren. Hybrid wine grape varieties are mainly 4-7 inches. Vinifera grapes are 2-4 inches for most varieties. Pre-bloom management of phomopsis, black rot and powdery mildew are the primary focus at this time. Wild grape bloom is expected soon. Wild grape bloom is used as the biofix for grape berry moth management later in the season.

Blueberries are at bloom or petal fall, depending on variety. This is still a good time to be scouting for mummy berry Spores are being released now and will spread with rain events later this week. Remember when applying fungicides to avoid applying when bees are flying- typically between 10 am and 4 pm. According to Enviroweather, Cherry fruitworm biofix was likely this past week, cranberry fruitworm biofix should be this week for growers in Berrien County next week for Allegan County. Biofix indicates when the adults start to be caught in traps. Fruit are required for egg laying and damage, so management usually begins after fruit set.

image-20220516-blueberry sloan — Blueberries are blooming throughout the region. Some varieties are beginning petal fall. Fruit biofixes will likely be set in the next week or two. Photo by Cheyenne Sloan, MSU Extension.

Strawberry bloom has begun. All the leaves are out by now, maintain fungicide coverage to protect the leaves and help prevent botrytis as fruit begin to show. With fruit beginning to form, western flower thrips populations should be monitored and appropriate insecticides used as needed.

20220516_strawberry — Strawberries are blooming. Some early varieties are beginning to show fruit set. Photo by Mike Reinke, MSU Extension.

Bramble leaves are unfurled. Shoot elongation has begun and new canes are emerging in fall bearing raspberry fields. In more advanced areas, fruiting buds are being seen. Raspberry sawfly scouting should begin. This insect causes leaf damage that can stress the plant, potentially reducing the crop potential.

Cranberries green leaves are beginning to emerge.

Currant and gooseberry bloom has ended. Many varieties are near 6mm.

Hops bines are growing again. The heat sped up regrowth. They are beginning to train up the strings.

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 Blueberry Prebloom Meeting will be held on Wednesday, May 18, 2022, from 1-4:30 p.m. at the MSU Trevor Nichols Research Center at Fennville, Michigan. The meeting will be In-person and via Zoom for those unable to travel to Fennville. We have prepared an interesting program addressing the topics that are relevant for the industry at this time of the season.

Join MSU Extension on June 9 from 5-7 p.m. for our Blueberry Preharvest Meeting at the Van Buren ISD in Lawrence Michigan. We will hear from MSU researchers and educators and have a few updates from industry leaders. We will send out more information as the program schedule is finalized. This program will be offered in person and virtually at no cost, so make sure and sign up today! It

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).