| Remember last summer's tomato blight on the East Coast? It wiped out much of the coast's entire tomato crop - and because it stays in the soil for YEARS, the entire region isn't out of the woods yet. But what if there's a variety of tomato that resists late blight? That was one of the things the Rodale Institute examined in their 2009 tomato tests.
They started out in 2008 by planting cover crops - rye and hairy vetch. They tested each cover crop's ability to fix nitrogen in the soil and to produce biomass that they would ultimately use as mulch to suppress weeds. In their tests, the rye was better at producing mulch and suppressing weeds, but the vetch fixed so much nitrogen in the soil that overall tomato yields were the same no matter which cover crop was used.
Then, in 2009, the blight hit. Rainy, cold weather made the blight worse than it might have otherwise been. Here's what happened:
Late blight survival varied by variety. The pathogen appeared on our plants in early August. We considered spraying with copper (a synthetic fungicide that is allowed but restricted within the National Organic Program), but decided against it because copper is expensive, doesn't work very well, and can poison the soil if it's used too much. We pulled out two of our varieties, Juliet and Pink Beauty, in hopes of slowing the spread of the disease. We were pleasantly surprised to discover that our sole heirloom variety, Striped German, was partially resistant to the blight. While some of the fruits developed the tell-tale late-blight lesions, the leaves were unscathed by the usual browning and withering of the disease. We left Striped German plants in the ground and they kept trooping along through early September, putting out big and tasty-if at times rather ugly-tomatoes.
Here's another interesting tidbit in the article (unrelated to blight):
Many organic farmers use plastic mulch to suppress weeds and warm the soil, but the use of plastic mulch has negative environmental consequences since it increases runoff from the fields, reduces soil organic matter by speeding up decomposition and often cannot be recycled after it is used.
I've seen plastic used a lot and it really bothered me. I'm glad that someone else is paying attention!!! |
