The Cougar Blight model over at NEWA is predicting a high risk of fire blight for this coming week, due to the coming hot weather and high humidity along with a chance of showers.
Currently April 26 looks like a high risk for infection in southern counties. 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 1-2 days protection and possible 24 hours back action. A predication of high risk over a 4 day period may require 2 applications 2 days apart, especially if there is rainfall, and/or the orchard is not yet at full bloom. Follow the label rates. Streptomycin can be applied at 24 ozs. per acre with the addition of a penetrant such as 8 ozs. Regulaid. Check your local conditions using NEWA and check back daily as the prediction may change. Remember to enter the date you first observed blossoms open.