Fusarium wilt and solarization
Over the past two years I have seen tomato plants at one end of my small (6' X 24') garden succumb to what I believe to be fusarium wilt. Pictures on the internet also suggest verticillium, but that seems less likely. I know that until I deal with the disease that part -- at least -- of my garden is unusable for tomatoes and other susceptible plants. Do you recommend solarization to eliminate the disease? And if so, can I do that on the portion of the garden bed (approximately 5 X 5) that has had these tomatoes (other parts of my enclosure have had healthy tomatoes), possibly extending the plastic another foot or so in all directions? Or do I need to do the whole garden bed? And related to this, if I solarize the space from, say, March through late June, might that be enough time to kill the disease? I am hoping to use that space toward the end of the season (a new tomato plant would still have time to produce). Or should I solarize throughout the summer?
Prince George's County Maryland
Were your tomato plants wilting? Tomatoes can wilt due to lack of moisture, too much moisture, and possible wilt and foliar diseases.
You will have to identify what you are dealing with. Wilt diseases in general, cause healthy green leaves and stems to go limp. Fusarium wilt on tomatoes is most common in MD. Take a look http://extension.umd.edu/hgic/fusarium-wilt-tomato-vegetables
Foliar diseases are often mistaken for wilt diseases simply because they cause defoliation and the plants end up looking wilted. Make sure your plants are not infected with one or more leaf spot diseases. These include early blight, Septoria, and gray leaf spot. All 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 Vegetable Website and look at photos and more information on early blight http://extension.umd.edu/hgic/early-blight-vegetables and septoria leaf spot http://extension.umd.edu/hgic/septoria-leaf-spot-vegetables.
If you suspect fusarium, solarization is not recommended. The best defense is to grow or purchase resistant varieties. If you suspect a fusarium problem, only select varieties resistant to race 1, race 2, & race 3 of this disease. However, under severe disease pressure, even plants with resistance may exhibit symptoms. Take a look at resistant varieties from Cornell. http://vegetablemdonline.ppath.cornell.edu/Tables/TableList.htm
Rotate tomato plants to another part of the garden or grow plants in containers (keeping infected soil out). You can also try grafted tomatoes.
Pull up and discard infected plants immediately. If you grow your own plants be sure to sterilize all plant growing equipment and supplies with a 10% chlorine bleach solution and use sterile soil-less growing media.
There is no cure for this disease. Plants must be removed and destroyed. When planting, avoid all wet spots and build raised beds if drainage is less than ideal.