> I apologise for the impromptu lecture on plant pathology,
> and thank you for your attention.
Don't apologize, plant pathology is very interesting.
> There are (as Dale points out) certain chemicals that
> cause plants to turn on these universal defenses (Actiguard,
> by Novartis, is one. Salicylic acid is another component,
It would be nice if organic growers could turn on systemic acquired
resistance (SAR) using non-synthetic chemicals. Can salicylic acid do this
in a practical sense?
> Mildews are just too specific.
Since SAR is a fairly generalized response, it might be possible to turn it
on in a plant using a non-specific, sub-virulent pathogenic assault. Are
their less fastidious pathogens that one could brew up and spray on to
trigger SAR, or would that be playing with fire? I am thinking of
facultative saprophytes that will germinate and "attempt" to infect almost
anything.
> The important thing to remember is that most plant pathogens
> don't cause plant disease on most plants. Disease is always
> the exception. Reactions to pathogens go from none to resistant
> reactions to susceptible reactions (disease).
Don't certain bacteria colonize the leaf surface? It is amazing to me how
seed-borne Xanthomonads and Pseudomonads can survive and propagate in plant
canopies, causing disease even under arid conditions. They must have a very
intimate relationship with the leaf surface. Of course, in the grand scheme
of things fungi are much more important pathogens Could fungal triggers of
SAR be put into leaf-surface bacteria to get generic SAR triggers?
Dale
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