Garden retailers can help prevent the spread of late blight in gardens and on farms this growing season and provide customers with the facts about this disease.
Know the FACTS about this important disease and share the information with fellow gardeners.
- Potatoes that freeze or fully decompose will not carry the pathogen over winter.
- Tomatoes will not carry late blight over the winter, because freezing kills the whole plant.
- Tomato seed, even from fruit that was infected with late blight, will not carry the pathogen, so no need to worry about the tomatoes left behind in the garden or compost pile.
- Certain perennial weeds can become infected with late blight, but none of their above-ground tissues live through the winter.
- Late blight will not survive on tomato stakes and cages.
The biggest threat for overwintered disease is on potatoes. In the spring, gardeners need to inspect last year’s potato plot and any compost or cull piles for volunteer potato plants that might come up. If potato plants are found, pull them out and put them in the trash or destroy them. If tubers were infected and survive, then the late blight could grow upward from the tuber, infecting the stem and producing spores when weather conditions are favorable. These spores could then disperse to other tomato and potato plants.
During the growing season, pay attention to pest alerts to learn about whether late blight has been observed in New England, and what actions should be taken. If you or a customer suspect a problem, or to confirm a diagnosis, contact the UMass Plant Diagnostic Laboratory.
- Late blight information and photos from Cornell University, College of Agriculture and Life Sciences.
- Regular updates on the situation and more information from the Department of Horticulture at Cornell University
Author Tina Smith is the Outreach Educator, UMass Extension, Amherst