For the last several years I've been fighting a leaf spot disease I believe...
For the last several years I've been fighting a leaf spot disease I believe to be septoria. I've followed the often quoted suggestions like crop rotation, pluck affected leaves, water early, use black plastic mulch, feed plants, use certified seed, etc. Each year the plants start out looking great but end up losing most of their foliage. I was thinking about a program of routine treatment with a copper fungicide but just read the results are not conclusive. What elese can I try? I'm losing hope!
Stark County Ohio
You didn't mention which crop this is concerning. If tomatoes, use of a resistant or tolerant variety would also help.The use of a fungicide containing chlorothalonil on a 7-10 day schedule is recommended. See the fact sheet at http://vegetablemdonline.ppath.cornell.edu/factsheets/Tomato_Septoria.htm for more info. A helpful tip for identification is that leaf drop normally starts on the lower leaves and progresses up the stalk. Also see http://www.news.cornell.edu/stories/2013/03/ready-plant-iron-lady-tomato-punches-out-blights and http://blog.pennlive.com/gardening/2010/01/fed_up_with_tomato_leaf_spot.html