By Blake Jackson
Pennsylvania orchards faced multiple fire blight infection periods throughout April and May. Growers with fire blight should review their spraying records during these times to identify areas needing improvement.
For apple scab, a major concern, the critical infection window fell between May 4th and 15th. Growers noticing apple scab should examine their spraying records from this period.
Fire Blight Management:
- Pruning Strategy: A "triage" approach is recommended, prioritizing young orchards with fewer strikes over heavily infected ones. In severe cases, significant pruning might outweigh the benefits.
- Pruning Tips: Prune during dry weather, make cuts early before infection spreads extensively, and avoid excessive cutting. Sterilizing tools is ineffective due to bacteria traveling ahead of visible symptoms.
- "Ugly Stub" Method: Cut 6-12 inches below visible infection signs, leaving a stub for later removal during winter pruning.
- Post-Pruning Options: Consider applying a high-concentration Actigard paint to the cut area or using prohexadione calcium (Apogee/Kudos) to halt infection spread.
Apple Scab Management:
Growers should also examine their spraying records from earlier in April for potential missed apple scab infection periods. Before blaming fungicide resistance, consider factors like sprayer calibration, water usage, weather conditions, and spraying practices.
- Fungicide Option: If controlling established apple scab, apply sulfur fungicide (8+ lb/A) when temperatures are consistently above 80°F, as infection is unlikely at these temperatures.
By reviewing their practices and implementing the appropriate management strategies, Pennsylvania orchard growers can minimize the impact of fire blight and apple scab on their crops.
Photo Credit: gettyimages-livingimages
Categories: Pennsylvania, Crops