TOMATOES - Late Blight

Tomato growers in the Northeast had a hard time last summer. Not only was our spring colder than normal, we had record rainfall. Tomatoes are natives of South America and they didn’t appreciate these growing conditions. To top it all off ... along came late blight which thrives with cooler, wetter weather.





My heirloom tomatoes were the first to bite the dust, although “black cherry,” which is much better than it sounds, continued to yield for a long time.


This disease started from infected seedlings grown in the south that were shipped to big box stores in the north.


The strain which caused last summer’s problem was the same strain that caused the Irish potato famine in the 1840’s. The blight releases wind-blown spores, and eventually most of us were hit, regardless of where we purchased our plants. Of course anyone reading this blog would only shop at locally -owned greenhouses, right?




KNOWING and PREVENTING Late Blight


For starters, if any of the diseased material ended up in your compost, definitely don’t use that near your tomatoes.


If you grow potatoes, don’t used saved potatoes as seed potatoes. certified clean.


Lesions on leaves will cross the center vein of the leaf.





Classic symptoms are large (at least nickel-sized) olive-green to brown spots on leaves with slightly fuzzy white fungal growth on the underside. Lesions on leaves will cross the center vein of the leaf.





Keep an eye on the foliage and remove and destroy anything that looks suspicious.


I will be planting more tomatoes in the greenhouse this summer. I have read that keeping water off the foliage slows the development of late blight. Home gardeners could try more potted tomatoes in spots under cover that get the sun.


‘Legend’ and ‘Juliette’ are both varieties that are said to have some resistance to this blight, so I will grow them as back-up. However the only thing I remember about ‘Juliette,’ which is a large cherry/grape type, is that the skin was really tough.


I’m almost finished with all my seed ordering and the next time I write I will list the tomatoes I am growing for customers and explain why I have picked those varieties.