Gretta’s late blight advice

Pests & Pathogens, Tomatoes

At the Seed Swap last weekend, Gretta (a local farmer, Shared Harvest CSA) talked with us about Late Blight. Her advice is to compost or dig in the tomatoes but make sure you remove all potatoes. The potatoes are the potential for spreading spores next year. Late Blight can overwinter in live plants (i.e. the potato tubers).

– DON’T let ANY undug potatoes sprout next year.
– Plant low crops in your old potato bed, so you can see and remove any sprouts.
– Try to dig ALL your potatoes this fall. It can be very hard to find them all. Have a potato digging party.

Less important is what you do with the tomato debris. These will not provide a live plant source for overwintering spores. Options:

– Dig in the tomato debris, layer on manure or compost, and plant cover crop. Turn this under in the spring.
– Compost the tomato debris and use it next year.
– OK to leave the plants standing in place and clean up next spring, but you should be layering on compost/manure and planting cover crops, so it makes makes more sense to clean it now.

And one more thing: in an area that was heavily infected by Late Blight (like my community plot), it doesn’t make sense to plant tomatoes or potatoes again next year. Try to plant somewhere else.

Here are sources for this advice:
UMASS extension Late Blight Management for Fall
Johnny’s Late Blight information

5 Comments. Leave new

  • Very happy to hear about the tomatoes. I hated the idea of dumping all that organic matter into the trash.

  • Great info! thank you for posting Gretta's advice. The UMASS article is really good!

  • I'm not sure where Gretta got the UMASS one, so I uploaded it.

  • This information makes me feel better about not getting the potato stems thrown away right away. My tomatoes get some kind of disease or other every year, so I always throw the plants away. I wonder if other diseases cause the need to throw them away.

  • Late Blight is the only disease where you need to dispose of vegetable matter and not compost. And for Late Blight the advice in the NE area now is that only the potates culls need be disposed of in the trash. Everything else can be dug in, left out, or composted.

    For all other diseases, the recommendation is buy healthy seed/plant stock and ROTATE crops. Don't plant in the same bed more than once in 3 years. I wouldn't plant any solanacea (tomatoes, potatoes, peppers, eggplants) in the same bed more than once in 3 years.


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