East Michigan fruit update – May 8, 2018

Bloom in apples is coming quickly, so look out for fire blight conditions.


Warm weather this past week has pushed our spring ahead very quickly. Our growing degree-day (GDD) base 42 totals have doubled in the past week, and finally with both warm daytime and nighttime temperatures, our GDD base 50 totals have nearly tripled in one week. Our season is still running seven to 10 days behind normal in terms of GDD totals, however when I look at growth stages, we are about five to seven days behind normal. We could have a very short or quick bloom period this season for our fruit crops.

Most of the region received between 0.5 to 1.5 inches of rain last Wednesday, Thursday and Friday, May 2-4. The wetting also brought the first major apple scab infection for most apple growers. Despite the rain, our soils have dried considerably over the same period. Most of the rapid soil drying came as a result of warm daytime temperatures and very windy conditions. A good amount of planting has taken place over the last two weeks. Most growers have completed planting.

Flower bud damage in peaches and sweet cherries from winter cold temperatures has become most apparent in the last week. Last week I reported some limited damage in a few varieties of apples. This week I am starting to find some wood damage in the cambium of apple trees, mostly in young trees between 3 and 5 years old. This is being seen in trees that were already stressed. It is unclear at this time the extent of this injury and if it can repair itself.

Beekeepers have been busy replenishing hives in an effort to prepare for the pollination of most of our tree fruit crops coming into bloom in the next week. I have seen a good number of bumblebees working to pollinate stone fruits in the past week, and yesterday it was nice to see a few honey bees working in sweet cherries and Japanese plums. Dandelion are in full bloom in many areas of east Michigan, which usually coincides with apple bloom, but not this crazy spring.

East Michigan GDD totals for March 1 to May 7, 2018





Commerce (Oakland County)




Deerfield (Monroe County)




Emmett (St Clair County)




Flint (Genesee County)




Freeland (Saginaw County)




Lapeer (Lapeer County)




Pigeon (Huron County)




Romeo (Macomb County)




Tree fruits

Apples are at first bloom in early varieties in the south and tight cluster to first pink in the north. Most growers have a nice crop of flower buds coming along this season. A new pest to report this week is first catch of oriental fruit moth adults in traps; a few growers had high enough number for biofix for this pest. High numbers (60 to 90) of redbanded leafroller adults are being caught in traps for the second week in a row, and yesterday I found a few redbanded leafroller larvae feeding in apple flower clusters. It is a bit early to see this feeding. Higher numbers (300 to 500) of spotted tentiform leafminer adults are being caught in traps.

I caught a good number of apple scab spores after last week’s heavy wetting event and resulting infection period for almost all apple growers. Except for growers in the southern tier of counties who had an infection period just at green tip, this was the first apple scab infection period of the season. This is unusual to have the first infection period so late in the season. Rain that is predicted for later this week will mean monitoring for any fire blight infection conditions.

Pears are at tight cluster to first white. Pear psylla adults are numerous.

Peaches are finishing bloom in the south and at first pink to first bloom for most of the rest of the region. Growers in the southern areas of the region have a good crop of flowers, so normal pruning can get underway for these growers. For peach growers to the north, the crop is extremely variable, with good sites having a full crop of flowers and marginal and poorer sites having just a few flowers. Pruning can begin in these areas as well, but the extent of the pruning will need to be adjusted to the crop load. It will be hard for the pruning crews to adjust from tree to tree as there is so much variability. Trees with a short crop will need to have much less pruning done.

Sweet cherries are at full bloom in the south and first bloom in the north. I see much less winter damage in sweet cherries than I am seeing in peaches. So, most growers can continue with normal pruning of sweet cherries.

Tart cherries are at full bloom in the south to first white to just a few first blooms open for growers to the north. There is a fair amount of fine wood or branch death in tart cherries at many farms this year. Most of this deadwood is the result of not controlling leaf spot last season combined with winter injury.

Plums are at tight cluster to first white for European types and Japanese varieties are at full bloom.

Small fruits

Strawberry flower trusses have emerged from the crown in the last few days, and new leaves have continued to emerge from the crown. These new leaves have not enlarged yet at many farms, likely because our soils were so cool this spring. Make a light application of nitrogen to encourage more leaf growth in what looks like will be a late harvest season for strawberries this year.

Raspberry canes have continued to emerge from the soil in summer and fall bearing raspberries, with the longest being between 2 and 3 inches in height. Some varieties of summer raspberries have started to leaf out. As this is occurring, some varieties have a good amount of dieback at the tip of the cane. This will need to be pruned back to living tissue over the next few weeks.

Blueberry flowers are at tight cluster and leaves are at late green tip. Pruning has wrapped up in blueberries.

Grapes are at early to late bud swell. Pruning continues in grapes.

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