Look for late blight on tomatoes and potatoes – Audio

Amanda Gevens
Extension Plant Pathologist
Department of Plant Pathology
UW-Madison College of Agricultural and Life Sciences
(608) 890-3072

Managing Late Blight in Home Gardens could mean less pesticide use on commercial crops

2:50  – Total Time

0:18 – What is late blight
0:34 – What is the status of late blight this year
0:50 – What should gardeners look for
1:53 – How to manage late blight
2:04 – How does late blight in home gardens affect commercial fields
2:40 – Lead out


Sevie Kenyon: Amanda, tell us, what is late blight?

Amanda Gevens: Yes, late blight is a plant disease which affects primarily tomatoes and potatoes, and it can spread in seed, it can spread in the air. And it’s a disease that both home gardeners, small farmers, and large producers of tomato and vegetable crop need to be concerned with.

Sevie Kenyon: And Amanda, can you tell us what the status is so far this year in Wisconsin?

Amanda Gevens: We did have our first report of late blight on potato on the eighteenth of July, and then just about one week later, we had a report of late blight on tomato crops.

Sevie Kenyon: And Amanda, what does this disease look like? What do people look for?

Amanda Gevens: What you want to look for is dark green to brown, often brown, but can be irregularly shaped lesions. What’s unique about these lesions is when the weather is hot and dry they will appear almost dry and papery, and almost black in color. And when we have very wet or high humid conditions, the lesions almost look greasy. They look very wet, and oily or greasy. Another aspect of this symptom to look for is a white fuzzy growth. It’s on or around these lesions, and you typically see them on the leaf underside or the lower stems of the plants.

Sevie Kenyon: How do you manage late blight if you see it in your tomatoes or potatoes?

Amanda Gevens: Initially, you can choose varieties that have resistance to late blight. Many home gardeners don’t want to apply fungicides. Fungicides are a pesticide. If that be the case, we do ask that you scout or look at those plants nearly on a daily basis then. If it is present, it ma be best just to remove that plant. And by doing that, you are reducing the amount of spores. That then is available to your neighbors’ tomato or potato plats, and area for commercial industry.

Sevie Kenyon: Amanda how important is it for people to manage this disease?

Amanda Gevens: It’s important for home gardeners, because any infected plants can produce spores. And while it’s unfortunate, when we lose home garden plants on a small scale, it can be potentially very economically devastating to our larger commercial producers. And so if we manage late blight well on smaller scale in home gardens, it can help us to overall limit pesticides use in our vegetable productions statewide.

Sevie Kenyon: We’ve been visiting with Amanda Gevens. Department of Plant Pathology, University of Wisconsin Extension, and the College of Agricultural and Life Sciences, Madison, Wisconsin, and I am Sevie Kenyon.

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