How can we prevent late blight on our tomatoes next year?
We have late blight on the tomatoes in our garden. We planning to pull out the plants and rototill. Is there anything else we can do or apply to the soil to prevent the blight next year?
Washtenaw County Michigan
You need to destroy the plants by burning or burying them some place you are not going to dig up for a long time. If the dead plant material goes into the compost pile, it will be ready and good for next year. But late blight is very much dependent on the weather. It takes cold nights, like we had, and lots of air humidity. We had that, too.
You can prevent late blight and other tomato fungal diseases by preventatively spraying with a fungicide beginning in mid-June or when the tomatoes get their first small fruit, whichever comes first. Use a fungicide containing chlorothalonil. This is applied every 7 to 10 days. You have to reapply after it rains and if you are using overhead irrigation. Be sure to spray the bottoms of the leaves as well as the tops. I have no information on how successful the organic fungicides are.