Northwest Michigan fruit regional report – April 1, 2014

The northwest region has had one warm day so far this season, and we still have lots of snow in the orchards and vineyards.

Weather report

We are accumulating growing degree days (GDD) very slowly here in the northwest, where warm days have been a rarity. We have accumulated 9.3 GDD base 42 degrees Fahrenheit and 0.7 GDD base 50 F. There has been variability in cold temperatures across the region. Some areas of Northwest Michigan sustained cold, overnight temperatures into the mid-20s, while in other areas temperatures only fell to -11 F. Michigan State University Extension educators suspect that the variability in overnight temperatures as well as the duration of the cold events will result in varying degrees of potential damage. However, we have substantial snow cover in the region, which has helped insulate trees and buds throughout this winter.

We did not have our “typical” January thaw this season, and the Leelanau County snow gauge is reporting just over 250 inches of snowfall so far this year. Snow has caused some damage in high-density apple orchards where some of the lower branches have been broken off by drifting and heavy snow. Growers are optimistic about the amount of ice covering Lake Michigan and our surrounding bays. Grand Traverse Bay has frozen over for the first time in many years, and because this body of water will take significant time to warm, spring frost events are less likely to cause damage to trees coming out of dormancy slowly. Many growers have commented that this winter has been like “the old days,” and we saw far fewer spring frost events in the 60s and 70s compared to the last decade.

Crop report

Trees and vines remain dormant at this time. We have cut some branches and buds from the Northwest Michigan Horticulture Research Center (NWMHRC), and although we have some damage in peaches and apricots, blossoms were evident when we forced them in the lab. Some growers have been reporting damage in peaches where they were only able to force vegetative buds and no flowers were visible. Sample sizes have been relatively small, and we will obviously know more as the temperatures warm.

Little damage has been observed in sweet and tart cherries from samples at the NWMHRC. However, we have had reports of damage in sweet cherries in younger orchards, 2 to 4 years old, but we have no numbers to report. Apples appear to be in good shape for this spring.

Rodent damage is the primary concern for growers at this time. We have observed significant rabbit damage where these animals have been able to feed at or above the snow line all winter. We have not quantified damage from mice because we still have too much snow in the orchards to see any damage at or near the graft union. Based on some initial grower reports, where snow has melted in their orchards, mouse damage is evident, even in orchards that used bait. Again, when the snow melts, we will have a better idea of overall rodent damage.

Bridge grafting is one option that may save trees with extensive bark damage. Refer to “Bridge grafting girdled fruit tree trunks” by Ron Perry for more information.

Dr. Rothwell’s work is funded in part by MSU’s AgBioResearch.

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