Friday, March 22, 2019

New season- Old question

Early tight cluster stage, Cripps Pink, central Virginia 3/20/19
The picture above was sent to me with the question,"Is it too late for a copper spray"? The short answer is "Yes, at this stage, it's too late for a copper spray on fresh market fruit. 

The explanation is that at tight cluster stage, among the flower cluster leaves you can begin to see the sepals and what will develop into the fruit. Because this is exposed, it is likely that copper will cause russet at this stage and would not be recommended. For processing fruit, where fruit finish is not a concern, copper applied at this stage will be a protectant fungicide for control of early scab infection and as a suppressant for later build-up of fire blight bacteria emerging from overwintering cankers.

At Winchester on Thursday Mar 21 we could see the earliest green tip on Red Delicious and this would be the ideal timing for copper application.

Our AREC NEWA weather station indicates early maturity (1%) of scab ascospores and this, coupled with wetting and temperature conditions, could result in early scab infection where unprotected green tissue is exposed. The Gadino Cellars NEWA station in Rappahannock County also indicates scab infection with 1% spore maturity and also forecasts possible infection for Mar 24-25. Scab infection is also predicted for Mar 25 for the Roanoke and Lynchburg areas, with 2-4% of scab ascospores mature.