Conditions Present For High Fire Blight Risk In East
May 5, 2015 “Folks, it’s shaping up to be another doozy of a spring for fire blight and you must heed the warning. Based on the prediction models, it might be a repeat of 2014,” writes Kari Peter of Penn State University.
Peter says the greatest risk is May 5-9.
This is also in line with what Dave Schmitt of Rutgers University advises. Rutgers uses the Network for Environment and Weather Applications and Washington State University’s Cougar Blight as predictive modeling.
“Growers should apply antibiotic to any apple or pear blocks with open blossoms prior to any risk of infection. Streptomycin and oxytetracycline formulations are generally thought to provide one to two days protection and possible 24 hours back action,” he writes. “A predication of high risk over a four-day period may require two applications two days apart, especially if there is rainfall, and/or the orchard is not yet at full bloom.
Researchers at West Virginia University’s Kearneysville Tree Fruit Research and Education Center, who host the Maryblyt management system suggest scouting for blossom infections on May 7 if there were open blossoms in your orchard on April 18, due to an early infection risk.
“Conditions are set for a bad fire blight year. React accordingly,” says the latest update. “Be aware that EIP (Epiphytic Infection Potential) and the threat of infection can build up rapidly if warmer weather than that forecasted occurs.”
If the EIP is less than 100% few infections are likely to occur. If EIP registers at 100%-150%, an epidemic is possible, but the chance is still low. If there is an EIP of 200%-250% or higher, the risk is high especially if a wetting event occurs.
Peter advises organic growers apply Cueva (Certis USA) at two quarts an acre with Double Nickel 55 (Certis USA) at one quart per acre.
For conventional growers, Peter suggests applying streptomycin to blocks with open blossoms.
“If conditions persist more than four to five days, you will need to apply two sprays during this period, especially if rainfall occurs and your apple trees are at different bloom stages,” she writes.
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