Tuesday, September 22, 2009
Can I Compost those Diseased Tomato Plants?
Yes. That’s the short and simple answer to a question that is on many gardeners minds. The disease that concerns most gardeners this year is late blight, Phytophthora infestans, which plagued so many gardens and farms this year. I have spoken to too many gardeners who are wasting time solarizing tomato vines, planning elaborate crop rotations or sending tomato debris out with the trash. Compost them. It’s also good to know that most diseased plants can be composted without the fear of aggravating the disease situation next year.
Let’s take late blight first because it is easiest. The late blight organism requires a living host to survive. Since tomatoes cannot survive our winters, any late blight fungus will die along with the plant. May as well compost the diseased plants. Or you could simply turn them into the soil. For that matter you could let the dead tomato skeletons hang out all winter on their stakes. Dead tomatoes = dead late blight. Late blight does not form overwintering spores in Pennsylvania that could cause new infections next year.
Potatoes are another story. Late blight infected potato foliage can be treated like tomato foliage. But infected tubers should not be put into the compost pile. Tubers may survive the winter and start up new infections next spring.
Most other tomato diseases do have the ability to survive and infect tomato again next year. Early blight, Septoria leaf spot and anthracnose can survive either on plant debris, in special fungal survival structures, on other plants and even on pots and containers. Crop rotation provides some small measure of control but you can expect these diseases to return each year regardless of crop rotation. And let’s face it, we often have limited ability to rotate crops in our small vegetable gardens. Do it, as a good general pest management strategy, but realize it will not eliminate re-occurrence of disease.
Back to that compost pile… since the environment in the compost pile is much more competitive for fungal pathogens than soil, and these disease organisms will survive thru other means, why not compost those diseased plants?
There are a few garden diseases that surely should not go into the compost pile. Fusarium and Verticillium wilt come to mind, but they are relatively rare these days because of good plant breeding. If you suspect that these are involved then trash them. Otherwise… everything into the compost pile.