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**carolyn137** · August 31, 2014

I have long said that PL varieties have greater tolerances to foliage diseases at many sites and for many years.

Not everyone would agree with me,which is fine.

But late in the season my RL plants could be down while most of the PL's are still doing OK. And of course that's a seasonal issue since spores and bacteria are not always present in any one season

What I have proposed is that the epidermis of the upper leaf surface of PL leaves is thicker than RL leaves so it makes it harder for the foliage pathogens to attach and infect.

I have not researched epidermis thickness for RL vs PL, so have no answers as to whether or not that's true.

So I don't see it as a genetic issue per se as related to a specific gene/alleles, I see it as a possible difference in the entire epidermal structures of RL and PL.

Carolyn

August 31, 2014	#3
carolyn137 Moderator Emeritus Join Date: Jan 2006 Location: Upstate NY, zone 4b/5a Posts: 21,169	I have long said that PL varieties have greater tolerances to foliage diseases at many sites and for many years. Not everyone would agree with me,which is fine. But late in the season my RL plants could be down while most of the PL's are still doing OK. And of course that's a seasonal issue since spores and bacteria are not always present in any one season What I have proposed is that the epidermis of the upper leaf surface of PL leaves is thicker than RL leaves so it makes it harder for the foliage pathogens to attach and infect. I have not researched epidermis thickness for RL vs PL, so have no answers as to whether or not that's true. So I don't see it as a genetic issue per se as related to a specific gene/alleles, I see it as a possible difference in the entire epidermal structures of RL and PL. Carolyn __________________ Carolyn