Looking at the estimated DD accumulation at the six sites listed in the table below shows that we are close to the end of ascospore release at all sites. As a conservative estimate, the final scab ascospore release in commercial orchards can be assumed to have occurred when 900 scab DD have accumulated before a daytime rain of at least 0.1 inch and temperatures of at least 50F during the wetting period. Based on our estimate of DD at the 6 sites we are monitoring, only Dummerston has reached the 900 DD mark. In other words, everyone should be covered during this rainy period. Please note it will take about 10-17 days after the final release and infection period to see if any lesions develop before sprays can be extended.
Powdery mildew is now evident on the undersurface of terminal leaves.
The fungus appears as white patches. Sprays during this time of the growing season are effective in curtailing the further spread of this disease on young leaves. The strobilurins and SIs are effective against powdery mildew. The warm weather predicted in a few days should make them more active. If pressure is not too severe, one spray should be sufficient, applied at 360 DD after the biofix date.