Posted: 09/07/2012 at 06:59
Good one, Bob. I've never had Leaf Mould problems but then I've never grown in a greenhouse. You hardly ever see it on outdoor crops.
Gard, LM is about the most common fungal problem for greenhouse toms. As Bob says, it's down to air circulation, the enclosed environs of the greenhouse effectively turning it into an incubator. You have to aim for as much ventilation as you can to keep introducing fresh air from outside. A friend of mine used an electric fan on low speed to help the process.
Rain can be one of the enemies of outdoor tom crops because of the wet foliage. Unless you spray preventively against fungal diseases+, all you can do is (a) keep a sufficient distance between plants - at least 3 feet - to help air circulation; (b) avoid letting clumps of foliage develop both on individual plants and between adjacent plants - hindering air circulation - by judiciously thinning foliage; (c) plant in a sun trap, a position that will let the sun dry the foliage as soon as possible; and (d) observe basic housekeeping practices like watering in the mornings, avoiding wetting the foliage, and maintaining a safety gap between the lowest branches and the soil.
+Even if you spray preventively you still need to observe the same fundamentals.
Unfortunately, for some reason, tomato growing seems to have been turned into a complicated process with a lot of misinformation circulating. For example, I read on a dedicated tomato website that a plant that wilts is ruined. Which is rubbish. Outdoor toms will wilt in the heat of the day. The key is to check the plant's condition after the sun goes down. If it has perked up again, no problems. If it's still drooping, it's an indicator that it's time to water. But the plant isn't ruined. This sort of misinformation is predicated on the notion that toms are delicate, sensitive plants. And they're not.
Tomato growing is a relative simple process. Observe basic cultural practices, don't pamper them, keep them alive, and let them get on with reproducing themselves.