Hello, we have grown tomatoes in a plastic tunnel for 20 years. Two years ago we got a aggressive leaf mold which defoliated the plants and killed them during the middle of the summer, we were growing heirloom tomatoes. We increased the spacing and added all the “resistant” varieties available from the catalogs, but still got less than 30% of the crop excepted due to leaf mold killing the plants. The so called resistant varieties appear only resistant to the “old” leaf mold strains which we used to get in Oct, when we closed the tunnel at night, not the new aggressive ones. Its not a very big tunnel, and is open 6’ on both sides so excessive humidity is not the problem. The extension service reported leaf mold problems on field tomatoes this year and blamed it on having tunnels near by, but this has never happened in the past before the new strain appeared . Does anyone have any advice on how to deal with this.
It is a major problem with at least 12 races of the fungi. Nothing seems to work. I would grow peppers for two years, or something else. The 3rd year it should be gone. It only infects tomatoes, unless a new race that infects other plants is around?
AFAIK nothing works. Good luck! .