West Central Michigan fruit update
No insect activity yet, but growers should be watching for wetting events and the potential for scab development.
Weather and crop development
This past week our area experienced very unsettled weather conditions. Over the weekend (April 16-17) rain and snow occurred from slightly below Bear Lake to slightly above Hart and Ludington with a half inch of precipitation. Noticeably cooler temperatures compared to a week before kept bud development at a very slow pace. Apples have not made significant advances in their bud development. McIntosh is showing very early to early green tip. Early blooming sweet cherries are at the side green stage of development. Tart cherries are still at swollen bud. Pears are at early swollen bud. Peaches have not moved much.
West Central Michigan Growing Degree Day Totals Since March 1, 2011. As of Sunday, April 17.
Get more weather data at http://www.enviroweather.msu.edu
There are no signs of any insect activity as of yet.
The rain event over the weekend produced the first apple scab spore discharge marking the beginning of the primary scab infection period for this season. Spores were collected in the abandoned apple block in Mason County. The number of spores was high for the first catch indicating that the snow cover provided excellent conditions for spore development and their survival this past winter. Though prolonged, this wetting event did not result in scab infection due to the low temperatures. The average temperature during the wetting period was from 37 (Hart and Ludington) to 39 degrees (Bear Lake). With green tissue present and mature spores ready to be discharged, future wetting events are likely to develop into scab infections.
It is necessary to follow weather forecast closely and act accordingly. Early scab protection will set the tone for the seasonal control. Copper applications targeting suppression of epiphytic fire blight bacteria will provide adequate first scab control as well. This year battling fire blight might be easier with use of Kasumin. This product has been approved for use under a Section 18 Specific Exemption.
Orchard assessment for the winter injury indicates that bacterial canker might be a problem this year particularly on young trees. There are excellent articles featuring early insect and disease control at the new website designed to bring you more timely information from MSU Extension.