Fruit IPM Advisory Fruit 2019

Fire Blight Risk on Late Blossoms


remove secondary blooms or spray with antibiotic before Friday afternoon

Because of the cooler spring, many apple and pear trees in Utah are experiencing a prolonged bloom period, or have secondary blossoms (also known as “rat-tail” blooms on pear).  These later flowers are at high risk of infection by the bacteria that cause fire blight.

The fire blight risk for much of Utah will go from low/caution today to EXTREME on Friday, and will remain at this high risk level.  With threats of afternoon rain showers on Friday, Saturday, and Sunday, these are perfect conditions for infection where blossoms occur.

If your trees still have significant blossoms, it would be worth it to apply an antibiotic today or early Friday.  The antibiotic streptomycin (Agrimycin) can be used up to 3 times per season, and (for commercial growers) Kasumin can be used up to four.  (However, Kasumin has a 90-day PHI.)

If there are just a few blossoms and if you have time and/or labor, it is worth it to go through your orchard/trees and hand-remove all the secondary blooms before Friday afternoon.