Disease management information directed mostly to the Frederick County Virginia tree fruit industry, updated as needed throughout the growing season. Keith Yoder, Virginia Tech Agricultural Research and Extension Center, Winchester, Virginia
Sunday, April 17, 2011
Scab and rust infection period
An apple scab and possible cedar-apple and quince rust infection period was recorded with 20-hr wetting from 2 AM-10 PM Apr 16. Temperatures through the wetting period ranged from 47-58F at the AREC but were as much as 4 degrees warmer in Winchester. Blossoms are now highly susceptible to quince rust. The 1.8-in. rainfall would have depleted most of the residue of non-systemic protectant fungicides applied this week, but an SI fungicide applied Apr 14-15 would have controlled any rust infection that occurred in this wetting period as well as the one Apr 12-13.