IS THERE A CO RELATION BETWEEN LEAF TYPES AND DISEASE SUSCEPTIBILITY OR RESISTANCE ?

I ask this based on my observations, among the varieties that I was growing this season. The ones with PL were stroke harder with diseases than the RL.

Cases:
POTATO LEAVES: Matina, Bloody Butcher, Stupice, JBT. all PL and had some persisting some kind of leaf mold, from early on.

REAL LEAVES: Ananas Noire, Legend, Cherokee Purple, Siberian, Mortgage Lifter, Pineapple : They did NOT have that problem.

I am thinking that it has to due with the mutation causing PL.
And I am also thinking to avoid heirlooms of PL varieties.

What has been your experience ? What is your opinion about my hypothesis ?

REAL LEAVES: ... What is your opinion about my hypothesis ?

That the answer is superficial! Not necessarily your hypothesis, but rather, related to the surface morphology of the leaf.

My understanding is that PL is a recessive trait compared to "Regular Leaf" and both leave types are the real McCoy when it comes to tomato leaves, my condolences Mr. and Mrs. Tomato for whoever gave it some of them the confusing name "potato leaf type" ;-)

Different leaves will likely do better with different pests. The larger, more uninterrupted the surface, for example, the more it could be fun for leaf miners if the thickness is ok, and ditto other pests in their preferred situations.

You'd need to do a randomized experiment for that if you want to determine any correlation. Other leaves might provide better cover, more convenient access to sap suckers, or be thicker or thinner favoring or disfavoring certain pests.

I realize your are talking about mold, and not pests and there are two thoughts ... if pests damage the leaves, there are more entry points for microbes, and second, serrated leaves are more open and airy so it really comes as no surprise that a healthy PL plant would have less air flow under a larger surface area which is a habit for mold, if you grow in a humid environment.

So I don't believe the "what is in the leaf" has anything immediately demonstrable to do with it since the explanations I would consider more likely are simply pests and diseases, taken as a whole, favorite environments. Were the leaves rugose, or not, etc. are all considerations much more important than any perceived chemistry from a miniscule gene change. Point is if you cross a PL with a serrated leaf I believe you get the serrated leaf predominating and your theory if taken "in the leaf" to mean composition, probably has no basis, but a literature survey would be needed to research the question better. Other growing conditions might favor the potato leaf just as yours might disfavor it. Plant genetics is all about filling every niche.

Hope that helps, and it is *not* time to hang up PL heirlooms!

PC, in a fantasy about crossing a PL tomato to get a potatillo plant … red potato shaped fruits in green lantern wrappers, and no grafting ;-)