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| Red Delicious bud stage March 18, 2017 |
Apple scab outlook: At our AREC in Winchester we had some early green tip on Red Delicious and other apples in early March, but they were still only about 1/4-inch green by March 18 (shown above). Apple scab ascospore maturation was initially delayed this year because of lack of snow cover and not much rain-wetting of leaves on the ground until March 6. We caught the first discharge of apple scab ascospores with five hours of wetting March 10. Snow cover March 13-17 helped to get the ascospore maturity up to date and more spores were discharged with melting snow and rain Friday night and Saturday, March 18. Expect abundant ascospore discharge with any additional wetting from here on out.
Scab infection could have been possible in other areas such as Rappahannock County and central Virginia as early March 6-8 if buds and spore maturity were more advanced and where wetting may have been more continuous through that period. At Winchester we had several periods that could be lumped together as a split-wetting infection period.
It looks like bud development will continue to be slow over the next 10 days. We often suggest a copper or other protective fungicide spray before the first scab infection period of the season. Copper should not be applied to fresh market fruit after 1/4-inch green tip stage because of potential for fruit russetting. It looks like there will still be opportunity to apply copper in the Winchester area this week. Where there is concern that scab infection may have occurred in the past day or two, it would be prudent to add Vangard (cyprodinil) to improve post-infection control. Dodine (Syllit) is another early season option where scab may be the only apple disease of concern up to pink stage.
We applied our bud swell spray for peach leaf curl February 24 and the wetting March 6-8 was probably enough to cause leaf curl infection.
Remarkably, peach and apple buds at our AREC do not show much commercial freeze damage considering the many freezing nights that we have had with wind since the earliest green tip on apples and bud swell-pink on peaches.
As a reminder, we have installed a publicly accessible weather station at our AREC in Winchester. The station, which updates hourly, is located near the laboratory building at an elevation of 933 feet. This station is part of the NEWA system, so to access it one can either click on the NEWA weather station locator map, or go directly to this URL:
It looks like bud development will continue to be slow over the next 10 days. We often suggest a copper or other protective fungicide spray before the first scab infection period of the season. Copper should not be applied to fresh market fruit after 1/4-inch green tip stage because of potential for fruit russetting. It looks like there will still be opportunity to apply copper in the Winchester area this week. Where there is concern that scab infection may have occurred in the past day or two, it would be prudent to add Vangard (cyprodinil) to improve post-infection control. Dodine (Syllit) is another early season option where scab may be the only apple disease of concern up to pink stage.
We applied our bud swell spray for peach leaf curl February 24 and the wetting March 6-8 was probably enough to cause leaf curl infection.
Remarkably, peach and apple buds at our AREC do not show much commercial freeze damage considering the many freezing nights that we have had with wind since the earliest green tip on apples and bud swell-pink on peaches.
As a reminder, we have installed a publicly accessible weather station at our AREC in Winchester. The station, which updates hourly, is located near the laboratory building at an elevation of 933 feet. This station is part of the NEWA system, so to access it one can either click on the NEWA weather station locator map, or go directly to this URL:
Explore the web site to view the numerous predictive programs that are offered there. We will refer to these more as the season progresses.
