Extension Plant Pathologist
Department of Plant Pathology
UW-Madison College of Agricultural and Life Sciences
Late blight resistant potatoes in development
Time – 3:13 minutes
0:13 – Late blight resistant potatoes in development
0:55 – How much of a problem is late blight for potato growers
1:36 – How resistant are the potato varieties that are being developed
1:48 – Typically, when do late blight symptoms appear
2:26 – What is the late blight forecasting tool and where to find it
3:03 – Lead out
Heading off the disease that caused the Irish potato famine. We’re visiting today with Amanda Gevens, Department of Plant Pathology, University of Wisconsin-Extension in the College of Agricultural and Life Sciences, Madison, Wisconsin and I’m Sevie Kenyon.
Sevie Kenyon: Amanda, you have some new information about resistance to late blight for potato growers?
Amanda Gevens: Yeah in potatoes we don’t have well characterized, readily available late blight resistance in commercially used potato at this time. What we do have, we have varieties in development that do have traditionally bred late blight resistance from sources that are known such as RB, the RB gene in potato cultivars does impart some resistance. But that’s very much in development, at this time our best defense against late blight in the potato crop is the planting of disease-free seed, good weed management in the field and early detection of the pathogen in fields.
Sevie Kenyon: Amanda, can you give us an idea of how broad this problem typically is for potato growers?
Amanda Gevens: Yeah in the potato crop, late blight is a great concern. And all growers of susceptible potatoes and tomato certainly have concern with this disease. We don’t look at one region of the state as having any higher risk than the other because there can be multiple sources of the pathogen in state. Whether that is potato seed, potato culls that may have been landspread, volunteers. In the tomato arena we certainly have risk with transplants being brought in that may have been infected by other sources. And any debris that overwintered in high tunnel greenhouses that could create another source of inoculants state.
Sevie Kenyon: And Amanda these varieties under development, how good are they?
Amanda Gevens: It’s a tolerance to late blight, but it is not complete resistance. So those varieties when released will still need to be managed in additional ways for late blight.
Sevie Kenyon: Amanda, when do growers typically start seeing symptoms?
Amanda Gevens: Symptoms of late blight can vary from year to year. As we’ve seen the disease over the last four years, symptoms typically become evident late July into the first week into August. But because we have so many potential sources of inoculums it’s hard to identify a month or even a week within a month that it is most often seen. What we do use to help us gauge when late blight may be present is a disease forecasting tool which takes into account temperature and humidity.
Sevie Kenyon: And Amanda if someone is interested in using this forecasting tool, what should they do?
Amanda Gevens: The forecasting tool is made available through my website at University of Wisconsin-Madison Vegetable Pathology. The utility in that is while we have site specific forecasts a grower or gardener can go to that site and find the closest site to their farm location or home location and utilize that forecast. While it’s not one hundred percent accurate when you are making inferences based on another location, it is good enough to get a general idea of when conditions have been met to favor development of late blight.
Sevie Kenyon: We have been visiting with Amanda Gevens, Department of Plant Pathology, University of Wisconsin Extension in the College of Agriculture and Life Sciences Madison, WI and I am Sevie Kenyon.