[Update 7-16-10: If you are searching for a reason behind leaf roll and curl that is not moisture-related, please read my more recent post on herbicide persistence in manure, grass, and hay causing trouble in home gardens!]
I have been watching some of my tomato and potato plants very closely in the last week, as some of their leaves are rolling up quite dramatically, and I’m a nervous wreck about having to rip out half of my potato crop and a third of my tomato crop.
But it looks like the problem here is a physiological disease–not a viral or bacterial one. Simply put–it’s the stress of the wet weather that is making the plants’ leaves curl up into tight little rolls. Thankfully (if I’m right in my diagnosis, and I sure hope I am!), this should resolve itself once things get a little more stable in terms of temperature and moisture, and it should not affect the plants’ production.
I am still a little concerned that all this moisture could incite a breakout of early blight or anthracnose–I remember a particularly wet spring on Vermont Valley Farm where our deliverable tomato harvest was cut by two thirds by those black, sunken patches developing on most of the fruit.
I am hoping that my system of mulching will help prevent the kinds of conditions (mainly soil splash onto the leaves and fruits) that favors a disease outbreak, but as nervous as I feel about saying this after last summer’s prolonged drought–it needs to dry out a little!
Strangely enough, though it’s generally recognized that heirloom tomatoes are more susceptible to this leaf curl problem, my biggest problem is on the determinate (bush) tomatoes. I think that’s because of where they are in the garden–a heavier clay area. The indeterminate/heirloom varieties seem unaffected, with the exception of the Japanese Black Trifele plants in the lower part of the north central garden.
I’ve also noticed that while one of the rows of Australian Crescent fingerling potatoes is affected, the other row further up the slope of the garden is unaffected (obviously, the lower part is staying moist longer). The Peruvian Purple potatoes are also quite badly rolled and curled–the soil is fairly heavy there, too.
Other than worrying over my nightshade members (well, the peppers and eggplant are just fine), I pulled the cover off the first row of carrots I’d planted and weeded them out, except for the accompanying dill (it volunteers wildly in that area of the garden). I’ll weed that out (um, I mean harvest it) for deliveries on Tuesday.
I’ll be keeping a close eye on the affected tomato and potato plants, and if things get any worse, I’ll consult the extension folks for a professional diagnosis. Stay tuned….