Late blight strikes potatoes, tomatoes

August-17-2012-Supplemental-E-6[1]Amanda Gevens, UW-Extension Plant Pathologist
Department of Plant Pathology
UW-Madison College of Agricultural and Life Sciences
(608) 890-3072

Amanda Gevens talks about the appearance of late blight in the state and what to do if you suspect the disease on your tomato or potato crop.



3:00  – Total Time

0:17 – What is late blight
0:39 – Crop loss possible
0:56 – Hits gardens too
1:19 – How late blight is managed
2:05 – Late blight found in Wisconsin
2:28 – Contact lab if you see late blight
2:51 – Lead out



Sevie Kenyon: Late blight rears its ugly head with potato and tomato growers. We’re visiting today with Amanda Gevens, Extension Plant Pathologist University of Wisconsin-Madison in the College of Agricultural and Life Sciences, and I’m Sevie Kenyon. Amanda, tell us first what is late blight?

Amanda Gevens: Yes, late blight is a potentially devastating crop disease that affects tomatoes and potatoes. It is a disease that can affect crops grown in the back yard garden all the way to larger commercial production of hundreds of acres.

Sevie Kenyon: And what are the affects of this if it gets ahead of growers in the state?

Amanda Gevens: Yes, if late blight gets ahead of our growers it means crop losses and not just within this production season, so when we have this disease we’re always thoughtful of the impact of the impact of seed for upcoming season.

Sevie Kenyon: And this can also affect the home gardener and the consumer in some ways?

Amanda Gevens: It can. Late blight, its spores can be around and move airily. If they land on a susceptible plant whether that be a tomato or potato plant, disease can result. So whether you have two plants out on a patio or you have eighty acres of potato crop that is susceptible, you can have disease.

Sevie Kenyon: What kinds of things do people do to manage this disease?

Amanda Gevens: In tomato systems there are varieties with very high levels of resistance and these can be available to home gardeners and direct marketers. In potato we have fewer varieties that have that level of resistance. The response to late blight, once you’ve planted a susceptible variety, needs to be fungicides. These fungicides in the commercial crop do start early and they start in response to a disease-forecasting tool that we use, which looks at weather conditions and determines when the weather has been most favorable for late blight to occur and indicated the need for a protectant fungicide application

Sevie Kenyon: And Amanda can you tell us what’s happening here this season?

Amanda Gevens: Unfortunately we did have our first detection of late blight in commercial potatoes. The response to that then is some destruction of crop to limit further spread. In other cases it means a tighter fungicide interval or the use of specialty fungicides to try to limit the development of late blight.

Sevie Kenyon: Amanda if people are concerned about late blight what should they do?

Amanda Gevens: If growers or home gardeners are concerned with late blight and they suspect they may have it, it is critical at this point that they take that plant material that is symptomatic to either a county agent, crop consultant, or contact me through the University of Wisconsin Vegetable Pathology program. Google search for UW Plant Disease Diagnostic Clinic.

Sevie Kenyon: We’ve been visiting with Amanda Gevens Extension Plant Pathologist University of Wisconsin-Madison in the College of Agricultural and Life Sciences, and I’m Sevie Kenyon.



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