My two cents:
Although streptomycin is degraded by light, this doesn’t really matter: For two
to four days, the antibiotic keeps bacterial population at low levels on
Once it’s degraded, the flower is also 2 to 4 days older and there is simply
not enough time left for the bacteria to multiply back to detrimental levels
Pusey demonstrated quite well that as flower age, they carry less bacteria and
become increasingly more difficult to infect.
Bottom line: Opened flowers that are sprayed stay protected for the life of
As Quan underlined, you should mostly concentrate on flowers unopened at
1) How many flowers weren’t open on the last strep spray?
2) Will the weather for these flowers be conducive for bacteria multiplication
If so, then you need to consider additional sprays for unsprayed flowers.
Trapman and myself developed RIMpro-Erwinia to help manage which flowers are at
risk and at need for a spray. This model is very different from Cougar and
Maryblyt and is proving more reliable.
Vincent Philion, agr., M.Sc.
Institut de recherche et de développement en agro-environnement
Research and Development Institute for the Agri-Environment
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