Step can generally last for 2-4 days without rain.  As it is degradable by sun 
light, it lasts longer in over cast days than in sunny days. Rain can wash some 
off but at least strep is more systemic than other antibiotics such as 
tetracycline. However, as it does not penetrate into unopened flowers, you 
would still need to consider putting done another application again 2 days 
later to make sure the newly opened flowers are protected by strep if the 
prediction models suggest a high disease pressure in your region.


Quan Zeng, PhD
Assistant Scientist & Bacteriologist
Department of Plant Pathology & Ecology
The Connecticut Agricultural Experiment Station
123 Huntington Street, P.O. Box 1106
New Haven, Connecticut 06504
phone: 203-974-8613

From: apple-crop <> on behalf of 
kellyorchards <>
Sent: Sunday, May 21, 2017 12:14:15 PM
To: Apple-Crop
Subject: [Apple-Crop] Fireblight

How long will strep protect blossoms that were open at the time
of application?

Art Kelly
Kelly Orchards
Acton, Maine
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