Appearance of apple scab, cedar rust and fire blight symptoms

On May 10 apple scab and cedar-apple rust lesions from the Apr 17 infection period were readily apparent on unprotected trees at our AREC. The scab lesions were advanced enough that they were probably sporulating early this week, so that would indicate a secondary infection period during the extended wetting May 6-8 where control had been inadequate to prevent infection Apr 17. Secondary powdery mildew infection is also common on unprotected new shoot leaves.

Also, fire blight blossom cluster symptoms were easy to see from our experimental inoculations Apr 18, Apr 19, and Apr 23, but not yet from May 1.