West central tree fruit update - May 1, 2018

Updates on development of key tree fruit crops in west central Michigan.

Sweet cherry buds on May 1, 2018. All photos: Dave Jones, MSU
Sweet cherry buds on May 1, 2018. All photos: Dave Jones, MSU

Cold weather in early spring has held back tree fruit development over the past several weeks. However, a return to more seasonably warm weather over the past couple of days has brought the first push of green growth. We are well behind normal growing degree day accumulation averages over the past 5 years. Most stations have accumulated less than half of the growing degree days that they had accumulated as of this date last year.

Growing degree day accumulations for west central Michigan as of 5/1/2018


Degree Days Base 42 Degrees F

Degree Days Base 45 Degrees F

Degree Days Base 50 Degrees F

Benona / Shelby




Elbridge / Hart












Apples are at silver tip to green tip, depending on variety and location. McIntosh is at green tip in much of the region. Growers who have green tip on varieties are busy applying copper ahead of the next three days of forecasted rains. Apple scab spores were first caught on April 12 in the region, so growers are anticipating the first major apple scab event with the coming precipitation. Green fruitworm and redbanded leafroller are just beginning to become active with the recent warm weather.

Tart cherries are at side green or green tip, depending on location. Growers should be carefully monitoring growth with the warm, wet weather approaching. Development may advance rapidly under these conditions in coming days. The first sprays for cherry leaf spot need to be out as soon as bract leaves are visible on trees. This may occur several days before bloom. This region got in trouble with cherry leaf spot last year during the bract leaf stage and it plagued us for the rest of the year, so growers are actively looking to address that situation this year.

Tart cherry buds

Tart cherry buds on May 1, 2018.

Peaches are at bud swell. Oriental fruit moth lures and mating disruption ties should be placed in blocks within the next several days. Michigan State University Extension recommends that growers who are able should try to rake away, bury or destroy brown rot mummies from last year, as these serve as a major source of inoculum for the disease in subsequent years. Many growers sprayed dormant oil this year to combat rising concerns over San Jose scale in the region.

Sweet cherries are at side green to green tip, depending on location. Copper for bacterial canker has gone out over the past two weeks, and dormant oil sprays targeting overwintering scale and mite populations are finished at this time. Growers who are still looking to prune sweet cherries should avoid pruning in coming days due to the rain on the forecast. Wounding sweet cherries during periods of warm, wet weather should be avoided at all costs in order to prevent bacterial canker from developing. Growers who have to prune sweet cherries in the spring should always be leaving a 6-inch long stub when removing a branch to prevent any bacterial canker infection from making it into the trunk of the tree.

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