Southeast Michigan fruit regional report – April 21, 2015

Warmer spring like temperatures late last week and over the weekend quickly advanced development of our fruit crops.


Tree fruit growers are seeing green tissue in most varieties. Small fruit growers are seeing new leaves emerging in strawberries and summer fruiting brambles; and new canes emerging from the soil for fall bearing raspberries; and swelling of buds and green tip in blueberries. Grapes are the exception with no visible growth. 

With warmer temperatures the growth of our fruit crops has picked up to a point where our season is back to normal in terms of degree day totals. Degree day totals have tripled from just two weeks ago and have doubled again in the last week.

Rain started on Sunday afternoon (April 19). Michigan State University Extension reports most apple growers applied their first apple scab control with most using copper.

With a general lack of rain this spring, our soil moisture conditions remain somewhat dry. Rainfall totals for Sunday/Monday and thus far today have only brought 0.25 to 0.55 inches of precipitation.

Most growers are completing their planting for the year, winter pruning, brush chopping and removal. Now is the time to set insect traps.

East Michigan Growing Degree Day Totals for March 1st to April 20th,  2015





Commerce (Oakland)




Emmett (St Clair)




Flint (Genesee)




Lapeer (Lapeer)




Petersburg (Monroe)




Pigeon (Huron)




Romeo (Macomb)




Tree fruits

Apples are at half inch green with a few early varieties at early tight cluster. With cooler temperatures expected for most of the week, growth stage advances will slow down. A few areas had a light apple scab infection period last Thursday (April 16), but all stations are currently reporting an ongoing infection period that started Sunday late afternoon. I caught a good-to-high number (90 per rod) of apple scab spores at my trapping location yesterday morning and another good number this morning as well. I was a bit surprised to see such a high number of spores for this early in the season. Most growers applied a copper spray ahead of the rain event and will go back fairly quickly. This could be a long wetting event, so there is a need to get back out quickly to re-cover.

Insect activity is starting to pick up for the season. I found a few spotted tentiform leafminer adults flying yesterday, but their numbers are still low. Redbanded leafrollers are starting to be caught in traps as well.  

I have not found any flower bud damage from extreme cold temperatures this winter in apples as of yet. Bud burst was a good time to accurately assess possible flower bud damage. Recall that last year there was significant damage to major scaffold branches and trunks in apples. This damage was not anticipated and was most pronounced in Golden Delicious and related strains. The damage did not begin to show up until mid-May or so, and resulted in total tree loss in many blocks. It is too early to assess this type of cold temperature damage.

Pears are at bud burst and show some bud damage due to cold temperatures this winter. Pear psylla adult flight was strong over the weekend.

Peaches are at swollen bud, but it is hard to determine in most blocks because most buds were killed this winter from extreme cold temperatures. Recall that peaches are one of the most cold tender tree fruits and flower bud loss is expected when temperatures fall below -13 degrees Fahrenheit. Most injury occurs between -13 F and -16 F. Most growers have significant flower bud losses, with flower buds appearing to be dehydrated and starting to fall off. It was so cold at many farms that I can see damage to twigs, scaffold branches and even trunks. This damage is showing as brown to cinnamon colored cambium tissue.

Sweet cherries are at bud burst with no early white bud visible yet. It appears about a third of the flower buds were damaged from the cold events of this past winter. Generally, two to three dead florets are seen in the flower cluster or bud. These levels of damage are greater than damage from a light frost during bloom or a wet, rainy day during pollination at bloom.

Tarts cherries are approaching early white bud. Tart cherries mostly show less damage in the colder sites than sweet cherries.

Plum damage is extensive in Japanese plums, however a few buds are now at bud swell. There is less winter damage in European plums as they are more cold hardy than Japanese types. Most European plums are at green cluster.

Small fruits

Strawberry leaves are just starting to emerge from the ground in the Flint area. Straw was removed late last week in more southern growing regions. If straw mulch has not been removed yet, I would suggest waiting for warmer temperatures.

Raspberry canes of summer fruiting types are starting to show leaf growth. Summer fruiting types have a significant amount of cambium browning, indicating potential winter injury. Fall raspberry canes are starting to emerge from the soil at most farms.

Blueberries are at bud burst to ¼ inch green. Initial bud assessments indicate damage in flower buds. The damage takes two forms: dead flowers in the flower cluster or bud, and withered shoot tips that dried from subfreezing conditions and cold winds. Generally, what we are seeing is several dead florets per bud.

Grapes show no movement. There is some damage in Concords and extensive winter cold damage to wine grapes, however damage varies greatly between varieties and sites. 

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