East Michigan fruit update – May 5, 2020

Fruit growth has finally taken off with warmer temperatures over the weekend. There is freeze damage to many fruits from cold temperatures on April 22. More cold temperatures are expected over the weekend.

Weather

We have had a springtime mix of temperatures over the last week, from cool last week to much warm temperatures over the weekend. The net result has been a nice sprint of growth in fruit crops and a good jump in degree day totals in the past week. Many of our growing degree day totals have almost doubled in the past week. This being said, our season is still three to 11 days behind normal for most of our MSU Enviroweather stations in east Michigan.

As an indication of how slow growth stages have been progressing this spring, forsythia has been in bloom in the last four weeks, which is much longer than I ever remember.

Another round of cold temperatures is predicted for this coming Friday, Saturday and Sunday mornings. For tree fruit growers able to frost protect, this will be a critical time, as well as for strawberry growers. Low temperatures in the range of 26 to 28 degrees Fahrenheit are predicted. For tree fruit growers, I would suggest a close mowing of grass before the predicted cold temperatures and to run irrigation to wet the soil prior to frost to lessen the effects of cold temperatures.

Even with rainfall last Wednesday and Thursday, soils remain dry for this time of spring at most farms. Planting of tree and small fruit crops is complete at most farms.

East Michigan growing degree day totals for March 1 to May 4, 2020

Location

GDD42

GDD45

GDD50

Commerce (Oakland County)

246

171

85

Deerfield (Monroe County)

319

230

128

Emmett (St Clair County)

237

163

80

Flint (Genesee County)

292

208

105

Freeland (Saginaw County)

231

158

74

Lapeer (Lapeer County)

268

189

96

Pigeon (Huron County)

183

119

52

Romeo (Macomb County)

252

173

82

Tree fruits

Apple growth stages have finally moved a bit in the past week. In the very southern reaches on east Michigan, most apples are at full pink to a few early flowering varieties starting to see just a few king blossoms open. Most of the rest of the region is at first pink showing on king blooms.

Late last week, growers started to see extremely crinkled leaves in many apple varieties. This damage was caused by cold temperatures on the morning of April 22. Many growers thought they had burned these leaves from either an oil application or an insecticide. This damage to these first few smaller leaves will not be a problem in the future, they just look tough at this time.

Yesterday, I was able to check apple flower buds from many areas of east Michigan, and growers to the south in Monroe, Lenawee and Hillsdale counties have a good amount of king bloom damage from freezing temperatures that occurred on the morning of April 22. Apple growers to north have less flower bud damage. Where there is damage, growers are looking at 40% to 60% damage.

Several insect pests have shown up in the last week. These include many farms with high redbanded leafroller adult trap catch, some trap catch is in the range of 140 to 160 adults per trap. Just a few very small redbanded leafroller larvae are being found. Many farms are seeing high numbers of spotted tentiform leafminer adults in traps, in the range of 700 to 800 per trap. This insect has not been a problem for most fruit growers for the last 20 to 30 years. A few farms are starting to find oriental fruit moth adults in traps. Some horticultural oil applications have been made and others are still planned for San Jose scale and mite control.

Predators are starting to show up this week, with a ladybug adults and green lacewing larvae starting to be found.

Most apple growers had their first apple scab infection period in rain over the region last Wednesday and Thursday, April 29 and 30. Most MSU Enviroweather stations in the region had a light apple scab infection period. Most growers applied their first fungicide application to control this early apple scab.

Herbicide applications are continuing to be made in apples and other tree fruit. Pruning and brush chopping has wrapped up in apples at most fruit farms.

Pears are mostly at first white. I have not seen any flower bud damage in pears from cold temperatures. With warmer temperatures over the weekend, I am finding more pear psylla adults flying than last week, their numbers are generally low to moderate.

Peaches have moved from first pink last week to full bloom this week in the south to king bloom from I-96 northward. With cold temperatures on April 22, I have checked a good number of peach flower buds since then and can’t see any widespread signs of cold damage to flower buds.

Sweet cherries are at full bloom in the southern parts of our region to first bloom as you move north. I am finding a good amount of freeze damage in sweet cherries from the April 22 freeze. Damage ranges from 40% in the southern parts of the region to 60% in the northern parts of the region. Some flower buds are still viable. The best way I can describe our sweet cherry crop is that we have gone from a good crop of sweets three weeks ago to a good crop of sweet cherries two weeks ago to an OK crop this week. All losses are due to freezing from cold temperatures on April 22.

Tart cherries are at first white. In cutting a good number of tart cherry flower buds yesterday, I can find more damage to flower buds this week than last week, all due to freezing temperatures on the morning of April 22. I estimate the damage to be in the range of 30% to 40%.

Plums are at first white for European varieties, Japanese varieties are at full bloom. I am finding some freeze damage in all plum varieties, around 40% to 50% in many varieties.

Small fruits

Strawberry flower buds continue to emerge from the crown. New leaves continue to emerge from the crown as well on fruiting plants, with some leaves in the southern parts of the region about half expanded. On newly planted strawberries, yesterday I saw a strawberry farm with small leaves emerging from plants. I have found several farms where a few of the flower buds on the earliest varieties are black from freeze damage. In the end, I don’t think this will impact our yield in strawberries. I am finding a good amount of grass from mulch germinating in strawberry plants in the past week, grass herbicides are being applied at this time to control it.

Raspberry growth has taken off with the warm temperatures over the weekend. Summer red raspberry leaves are 1 inch in length and newly emerging canes are 3 inches in length. Canes on fall raspberries have emerged and most are 2 to 4 inches in length.

Blueberries are at tight cluster to early pink bud. I have seen some damage to flower buds in Jersey, but none in Blueray or Bluecrop varieties.

Saskatoons are at balloon stage.

Grapes are finally starting to move with some at early bud swell.

Haskaps are at petal fall for most flower buds. They flower over a long period of time.

This article was published in Futures, a magazine produced twice per year by Michigan State University AgBioResearch. To view past issues of Futures, visit www.futuresmagazine.msu.edu. For more information, email Holly Whetstone, editor, at whetst11@msu.edu or call 517-355-0123.

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