Written by Tianna Dupont, WSU Extension; Ken Johnson, OSU, April 6, 2020. Revised Feb 1, 2021.
The last few years have built up fire blight inoculum in our orchards. Consider designing a toolbox of plans you can choose from depending on the risk in each block and how spring progresses.
Think about which are your high-risk blocks: blocks with sensitive varieties, high-value varieties or a history of fire blight. Those are blocks where you may want a more intensive program. Think about what fickle mother nature may do. Have a plan for moderate temperatures and extended bloom as well as flash bloom. Below is an example of a set of plans a grower might design to choose from for different blocks and conditions.
Apples | ||||
Conventional | Organic | |||
Low to Moderate Risk | High Risk high value varieties history of blight |
Easy to thin varieties | Hard to thin varieties/ short bloom period |
Hard to thin varieties/ long bloom period |
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a Apply to every row. Two applications between 50-100% bloom have the best efficacy.
b Spray tank acidification has been most significant for oxytetracycline products (e.g. Mycoshield).
c Lime sulfur at this timing can interfere with oil sprays for mites.
d Rotate. Rotation is necessary for resistance management. Rotate as necessary to comply with application intervals for individual products. Do not apply Actigard at closer than 7-day interval (label restriction). Streptomycin should be used NO MORE than one time per season.
e Kasumin may not be applied after petal fall.
f Blossom Protect+ Buffer Protect, then Previsto (full bloom), then Serenade (petal fall) best organic combination in 13 trials at 83% relative control (Johnson) similar to antibiotics.
g Remember Blossom Protect yeast need about 12 hours to grow on the flower to protect blooms before a wetting event.
Pears | |||
Conventional | Organic | ||
Low to Moderate Risk | High Risk | Easy to Mark Varieties Anjou/ Comice |
Marking Tolerant Varieties Bosc |
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For more information see: http://treefruit.wsu.edu/crop-protection/disease-management/fire-blight/
Contact
WSU Extension Specialist, Tree Fruit
tianna.dupont@wsu.edu
Office: (509) 293-8758
Mobile: (509) 713-5346
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