Last night's wetting (14 hr at 63-54° with 0.21 in. of rain) was favorable for scab, quince rust, and cedar-apple rust. The blossoms are now very susceptible to quince rust and, if protection was questionable, a follow-up including an SI fungicide for after-infection is advised.
This was our 6th apple scab infection period this year. Apple scab lesions were observed on unprotected trees at our AREC this week. Where protection was inadequate during early primary infection periods Apr 7-10, consider this and any additional infection periods in the Winchester area to be secondary ones, with high inoculum potential on very susceptible blossoms and leaves.
Outlook for fire blight in the Winchester area remains similar to what was posted yesterday: with warming through the weekend and warmer temperatures predicted all of next week, essentially all of the components will be such that any wetting of susceptible, unprotected blossoms could trigger infection any day next week.
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
About Me
- Keith Yoder
- Professor Emeritus of Plant Pathology, Virginia Tech Ag. Research and Extension Center, Winchester, VA
