Northwest Michigan fruit update – April 19, 2022
With the cool weather, trees and vines remain dormant. Spring is slow to show up this year.
Cool weather continues in the northern part of the state. We also had snow that is sticking but not much accumulation. Jeff Andersen, Michigan State University Extension state climatologist, says we will continue to be cloudy and cool for Tuesday and Wednesday, and rain will move into the state late Wednesday into Thursday morning. There is forecasted rain again on Friday into Saturday morning. However, by the weekend, the forecast is predicted to be warmer but rain will move back into the region by Monday. Weather is forecasted to be in the mid-60s by the weekend but cool weather for the remainder of the work week. The medium range forecast is predicting cooler than normal temperatures through April and into middle of May.
The rainfall and snow melts have been notable this year. We have accumulated 5.33 inches of moisture since the end of March in 2022, and our 23-year average is 1.66 inches. Soil moisture is looking good for this time of the year.
Tree fruits remain dormant for the most part. We did note some swelling in the sweet cherry variety Gold, but most tree fruits are still quite tight. This cool weather is expected to continue, so growers will have a nice slow start to spring this season. Since Jan. 1, 2022, we have accumulated 51 growing degree days (GDD) base 42 and 12 GDD base 50. Since our report last week, we have only accumulated about 20 GDD base 42 and 6 GDD base 50.
Pest and disease report
With the continued cool weather, we have no reports of insects or disease concerns. Cool and wet weather is favored by the pathogen that causes the bacterial canker disease, so wait for a stretch of warmer and drier weather to prune sweet cherry trees. However, the forecast does not look conducive for pruning sweet cherries until later in this month.
Peach leaf curl information
The following is from Bill Shane, MSU Extension fruit educator.
Peach leaf curl infections occur when wetting periods over 10 hours occur under cool conditions (46 to 53 F) with rainfall greater than 0.5 inches. This is an effective range of approximately 7 degrees. This is remarkable when you consider cherry leaf spot and apple scab can cause infections over a much wider temperature range — more than 30 degrees. These rather specific conditions may not occur every spring, which explains why some years peach leaf curl does not show up on unprotected trees. Leaf and fruit buds are vulnerable for several weeks after swelling, as are new leaves produced on terminal growth on into the summer. However, episodes of cool temperatures and extended wetting generally become uncommon as the spring progresses.
The occasional infections that show up on new terminal growth in midsummer are due to unusually cool wet weather. The time between infection and first symptoms ranges from nine days under warm conditions to nearly a month.