late blight on tomatoes

Asked August 11, 2013, 12:51 PM EDT

I haven't had a confirmation that what hit my tomatoes is late blight, but after watching the webinar from Cornell Extension, I am pretty sure it is. I will take a sample to be tested but with the remaining plants it was advised to remove the plants, bag them and leave the bags in the sun. Could they also be burned? What about the supports that were used with the plants? Should they be burned or discarded as well or is there some way to "disinfect" them? Thanks.

Wayne County New York

1 Response

The supports should not be a problem. You can leave them in the sun to kill any living fungus and you could wash them off with a bleach solution just to be sure that they are clean of any spores which might have landed on them.

The spores can be formed in two ways. One is asexually and usually spread in the wind. If they do not find another host, they die. They do not over winter.

If, by chance, you have two types on your plants which can mate and form oospores, the spores formed can overwinter in the soil. Removing all the plants minimizes the chance of this later type of reproduction taking place. I could not find any reference to whether the spored from this kind of mating can survive a fire so burning may kill everything.

The plastic bag generates enough heat from the sun to kill much of the fungal growth. This may not kill all of the spores but they are contained and you can then trash the bag and any potential infection goes with it.

Here is an article which will give you the concerns and the problems with dealing with this disease.
http://www.longislandhort.cornell.edu/vegpath/late_blight_recent_future.pdf

Here is the sight with more references on late blight
http://www.longislandhort.cornell.edu/vegpath/photos/lateblight_tomato.htm