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Bethlehem CT

I just received my SNGPG newsletter and in it they have some pictures posted of Dan Macoys record tomato and the plant it grew on. My question is, What causes the leaves on his plants to curl up like that? I have never had that happen. Thanks

9/4/2014 6:59:30 AM

Western PA

I am looking for that answer as well, since several of my plants , out of 20 total, have that leaf curl also. I fertilized very little this year with all the rain.

9/4/2014 8:28:03 AM

Ely Mn

not sure....lol like Zappa didnt give it much ferts at all.
just whats in the soil.

9/4/2014 9:07:07 AM

Allentown, PA

Leaf curl is the plants way of signaling stress. Not only can over fertilization cause this but also too much or even too little moisture. The bottom line is that leaf curl affects the plants ability to grow the tomato very little.

9/4/2014 9:15:17 AM

Central Minnesota

Any plant I prune has leaf curl. I let one plant go and did not prune it at all, it has zero leaf curl. First I thought it was over fertilizing but the plant without the leaf curl is getting all the same stuff. Right now I am leaning toward the aggressive pruning that leads to leaves to curl but that is just a guess right now.

9/4/2014 11:43:24 AM

East Carbon, Utah

It's an intriguing observation because the leaves certainly don't look all that healthy. But who can argue with Dan's phenomenal success in 2014?

I posted a response to this some question at The Tomato Depot. Some overlap with what's already been said. But I'll duplicate the entire response here:

= = =

"My understanding is that this phenomenon is "Physiological Leaf Roll". This occurs when the plant is stressed by cool weather or hot weather and is neither a disease nor detrimental to the plant. The leaves simply thicken to protect themselves against future stressors, perhaps analogous to a suntan for those with less active melanocytes.

Virtually all of my plants show this condition, particularly on the older leaves. And since Dan pruned off all new growth early on, all of his leaves are old leaves! I've found Big Zac (OP) to be particularly susceptible to this condition.

My guess is that on at least one day, Dan left the greenhouse closed up a little too long and it got to 120° or warmer in there. I did that once - neglected to ventilate my high tunnel until it had already become very hot inside - and the result was that a few days later I had a massive outbreak of huge megablooms!

It's got me thinking... But I really have no evidence for the cause-effect relationship I've implied. If Dan also made this "mistake", then two such independent observations might justify formulation of a testable hypothesis...

Unfortunately none of my early massive megablooms amounted to anything this year. I just could not get enough pollen for them. Next year I plan to grow my giant tomato plants in pairs. One unpruned for pollen production and crosses, the other SEVERLY pruned for competition. Actually I'm thinking I should start the let-it-grow plants about 1 month earlier than the competition plants. That way I can be almost assured of at least some extra pollen."

= = =

9/4/2014 3:41:41 PM

Jericho Vermont

I am not a giant tomato expert but all of the leaves I have on my tightly pruned plants have the leaf curl as well. The non pruned plants did not.

9/4/2014 5:00:28 PM

Ely Mn

it never got close to 120.but 100 is possible.
it probly is related to a few hot days, its hard to keep it below 90 in there when its 85 and sunny.wich was rare this year.very cool august,not sure if we even hit 80 more than 2 times.it got down to 39 one night mid august.

9/4/2014 8:27:46 PM

valparaiso, in

I notice that my leaves curl after an unusually cool night. As the plant grows I can tell by where the leaf curl is when the cool night happened. Not scientific just an observation. I do not prune my plants as much as others do.

9/4/2014 10:07:34 PM

Bethlehem CT

This is really interesting stuff.

9/5/2014 7:00:32 AM

France

leaf curl is caused by excess water + little excess of fertilizers but it's not bad, tomato continues to grow.

9/5/2014 7:11:17 AM

France

plant great vitality = leaf curl

9/5/2014 7:15:07 AM

Johnston, Iowa

All of my plants this year had that curled leaf phenomenon. At the time, I attributed it to the cool weather we were having, esp since other gardeners in my area told me they were seeing the same thing.

9/5/2014 11:28:01 AM

Muddy Waters

mine curled all plants are outside.they seemed to curl the most after being fed the next day BAM!!

9/5/2014 9:09:16 PM