Southeast Michigan fruit regional report – May 13, 2014

Warmer temperatures in the last week are finally pushing rapid growth of our fruit crops, insects and diseases, too.


With warmer temperatures in the last week, growth and development of fruit crops are finally trending back toward normal. These same conditions have also brought increased disease and now insect pressure. With bloom underway at apple farms in the southern parts of the region, the risk of fire blight is upon apple growers.

Our season continues to run behind normal, but now only four to seven days behind normal instead of nearly two weeks. The Michigan State University Enviro-weather stations in our region have finally accumulated a good number of growing degree days (GDD) in the last week.

Most fruit growers report rain events four out of the last seven days, with many growers seeing very heavy rainfall totals on Wednesday evening, May 7, and all day Monday, May 12. Rainfall totals varied greatly over short distances, generally ranging from 0.3 inches in the Thumb to nearly 2 inches in other areas. Some farms had a total of 4 inches of rain in the last week. A few reports of light amounts of pea-sized hail have also been made from these two thunderstorm events.

Pest control operations are in full swing at most farms. Frost is predicted later in the week, so strawberry growers will need to be ready to frost protect. Soil moisture was just right at many farms early last week before the rains hit, allowing fruit growers to do a fair amount of planting. Most growers have finished planting for the year. Orchard fertilizer applications are being made as soil conditions allow. Pruning of apples and brush chopping is wrapping up at most farms.

East Michigan GDD totals for March 1 to May 12 , 2014





Commerce (Oakland)




Emmett (St Clair)




Flint (Genesee)




Lapeer (Lapeer)




Petersburg (Monroe)




Pigeon (Huron)




Romeo (Macomb)




Tree fruits

Apples are at king bloom in the southern areas of the region and at pink in the Flint, Michigan, area. Many growers applied oil last week. Most farms have had two fungicide applications in the last week for apple scab control, and many growers are considering a pink spray in the next few days (more details to come in future reports). Some of the apple flower buds are not developing as quickly and as fully as they normally do. I am not certain if this is a delayed winter injury or that some buds may be in a deeper state of dormancy and will take more time to develop. I am concerned that a few flowers in Ida Reds have opened early and are only dime-sized when fully open. This is odd and bears watching to be sure others develop normally.

It appears that we will have a long and widely spread apple bloom this year. Some Honeycrisp, Red Delicious and Fuji blocks appear to have light bloom this year; most other apple blocks generally have a good number of flowers this season. Growers doing bloom thinning will need to begin soon.

Insect pest pressure has finally begun to pick up in the last week due to warmer temperatures. The first oriental fruit moth was caught in a trap late last week and much higher numbers are being caught this week. I am starting to see a few tarnished plant bugs feeding in apple clusters. Much higher numbers of spotted tentiform leafminer adults and redbanded leafroller adults are being caught in insect traps in the last week. Several species of leafroller larvae are now being found in apples. I have seen a few European red mites just starting to hatch.

Insect pressure has been high enough at many apple farms in the past few days that I have made more than my normal share of pink cover spray recommendations to help bring down insect populations before bloom. I am continuing to see a few predators. Oil applications were made last week at most farms. It is not too late for oil in the Flint, Michigan, area and to the south.

With bloom in the south and fast approaching in other areas, the risk of fire blight infection is now upon apple growers. Most farms had a fire blight infection in the last day. All of our MSU Enviro-weather stations recorded one or two apple scab infection periods in the three to four wetting events of the last week. Most had a heavy infection period on Monday, May 12.

We continue to have apple scab spore release in each rain event, with 348 spores trapped in the last one. This is a good number of spores for this time in the growing season, indicating a higher than normal apple scab spore pressure this season. This past week has been a frustrating one for apple growers dealing with so many apple scab wetting events.

Pears are mostly at king bloom. Pear psylla adults continue to be very active with this warmer weather. It is present in all stages at this time. Michigan State University Extension advises pear growers to keep an eye out for fire blight infections.

Peaches continue to be in a sad state of affairs at most farms, with many varieties not leafing out and flower buds continuing to dry and drop from the tree. However, in the last few days I have just started to see a few leaf buds beginning to develop in the most vigorous shoots in the tops of trees. It is too early to tell if this is a sign of hope that these peach trees might survive the extreme cold winter and be viable to bear a crop of fruit in future years. I need to watch this growth carefully over the next three weeks or so to see if this growth continues or collapses when under the first stress of the season.

Trees that were under stress last season or are past their prime-bearing age appear to be dead or dying. Cambium tissue in twigs, scaffold branches and even trunks that were damaged from cold temperatures this winter are turning to a darker brown color. This is another bad sign for the potential of long-term injury in peaches. It appears that there is extensive winter damage in peaches this season, comparable to cold damage that occurred in the winter of 1994.

Sweet cherries are at full bloom to petal fall, depending on the variety. I was pleasantly surprised to see more bloom in sweet cherries than I expected.

Tart cherries are at full bloom. It looks like there was less damage in tart cherries than sweet cherries this season.

Plums are mostly at white bud to early king bloom for European types and full bloom to early petal fall for Japanese types.

Small fruits

Grapes are at late bud swell for Concord and Niagara. Wine grapes are showing extensive cane death in most varieties. There is between 60 and 80 percent winter damage in wine grapes at most farms this season due to winter injury.

Strawberry flower trusses have now emerged from the crown of the plant. Frost protection is now needed to protect these flowers. Leaves are finally elongating and are starting to look more on the normal side. I suggest a light application of nitrogen at this time to push strawberry growth a bit and add some vigor to most plantings. Angular leaf spot disease has been reported this last week at several farms, however in light amounts. Growers need to do a thorough job of scouting at this time to check for the angular, water-soaked translucent lesions on leaf surfaces. A copper application may be needed at this time to control angular leaf spot.

Raspberries are continuing to show signs of winter injury, especially summer red and black raspberries and blackberries. Some varieties that were starting to show green tips on the buds have stopped new growth and are continuing to shrivel. Canes of summer fruiting types have a significant amount of cambium browning, indicating potential winter injury. Fall raspberries continue to emerge from the ground and are now 2-4 inches in length. There was some death or browning to newly emerging canes for fall bearing raspberries from frost that occurred a few weeks ago.

Blueberries are mostly at early pink bud. Some twigs continue to die in many blueberry varieties due to winter injury.

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