Late Blight Webinar 2010: 1 - Importance of this Plant Disease

eOrganic authors:

Dr. Margret McGrath, Cornell University

Dr. Sally Miller, Ohio State University


This clip is from the Late Blight Control in Your Organic Farm Webinar

Audio Text

I'm going to start this evening by talking about the importance of late blight. Then, Sally's going to give her presentation, and then I will come back and talk about occurrence and management. So to start with, the reason we are having this Webinar is that late blight is a really important disease and we're going to make sure you all understand that. It is arguably the most destructive disease that we have. It can decimate production areas pretty darned fast, unfortunately. It can be very difficult to manage. It generally requires inputs of fungicides, and it's especially difficult to manage after it has started, which makes it very difficult. Generally, we like to wait and see a disease outbreak before we decide whether to intervene, but that can be very hard with late blight. It is a highly contagious disease. The pathogen produces an abundance of spores of that white fluffy stuff you see on the undersides of leaves. Those are easily moved by wind and can move on to another garden or farm. Plus, it becomes a community disease. We all need to know where late blight is occurring and that helps us in being able to manage it in our own gardens or farms. Here is one example here that I wanted to share with you just to illustrate how destructive this disease can be. This is an organic farm where I am. Last planting, when symptoms broke out, just before fruit were going to be ripe, symptoms on the leaves, on the fruit it was first seen, and some of the plants were extremely severely hit. This is the first time this farmer saw it in his planting. Clearly too severe to have managed it. He had been applying copper, but it had been ten days sense the last spray. There just wasn't enough material there to protect the crop. He tried to save it, but was unable to save it. I just wanted to share that story to illustrate how destructive these can be.

And now, we have a quick poll question for you all and we'd all appreciate knowing who has had late blight on their farm in the past or in your garden. If it has been every year, just only this past year. So you've got about twenty seconds, if you don't mind, helping us out by giving us some feedback on whether or not you've had late blight. I think it will help us all to understand where it has been, and then we will move on with the presentation.

So, it looks like most of you only had late blight last year. Very interesting. Thank you very much for your time.



Published July 23, 2010

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