[Apple-Crop] Fireblight

[Vincent Philion]

Hi all,

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 sprayed flowers.

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 and infect.

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 that flower.

As Quan underlined, you should mostly concentrate on flowers unopened at spraying time:

1) How many flowers weren’t open on the last strep spray?

2) Will the weather for these flowers be conducive for bacteria multiplication and infection?

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.
Microbiologiste/Phytopathologiste (pomiculture)

Institut de recherche et de développement en agro-environnement
Research and Development Institute for the Agri-Environment

www.irda.qc.ca<http://www.irda.qc.ca/>
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