I've been vegetable gardening here in Monkton since 1986 and I've had a...
I've been vegetable gardening here in Monkton since 1986 and I've had a recurring problem with my tomatoes. They grow well but as soon as the plant starts to mature the lower leaves develop dark spots, turn yellow and fall off. After the main crop has finished, most of the vines have lost their leaves and the remaining tomatoes that develop are often scalded. I've tried just about every variety that's available but it doesn't seem to improve the situation. I've even moved them a considerable distance to new areas but that didn't help either. I've attached a photo of the vines in the late season showing the bare stems with only the fresh growth at the top still green. Can you identify the problem and make any recommendations to correct it?
From your photo it looks like your tomato plants may be subject to one or more foliar diseases such as early blight or septoria. You will have to identify what you are dealing with. Also, we notice the plants are in some shade. Tomatoes will be most productive in 8-10 hours of sun and 4-6 sq. ft. of growing area.
These foliar diseases produce spots or lesions on leaves, start at the bottom of the plant and progress through the season if conditions are right, to defoliate tomato plants (spotting, yellowing, dying.) Go to our Plant Diagnostic Website and look at photos and more information on early blight http://plantdiagnostics.umd.edu/level3.cfm?causeID=275
septoria leaf spot http://plantdiagnostics.umd.edu/level3.cfm?causeID=1389, and
gray leaf spot http://plantdiagnostics.umd.edu/level3.cfm?causeID=1390
These links will give you management information.
It may also be helpful to view our Profile http://extension.umd.edu/learn/vegetable-profiles-tomatoes and our publication on tomatoes http://extension.umd.edu/sites/default/files/_images/programs/hgic/Publications/HG56%20IPM%20Tomatoe...