|Last year many tomato plants were affected by a fungus that totally wiped out tomato plants. What precautions do i need to take with planting my tomato plants this spring? Can I use the same dirt in my pots?|
|Since the fungal spores can be soil-borne, I'd empty the pots and wash them with a bleach and water solution before filling them with fresh potting soil for this year's tomato crop. You can use the potting soil in other areas of the garden or you can grow different kinds of plants in the potting soil.
Last year your plants may have been attacked by either Early Blight or Late Blight. Early Blight is caused by the Alternaria fungus. It overwinters on infected plant material, even seeds, so it's hard to completely remove the spore reservoir from the garden by cleaning up all the vines and fruit. Early Blight works slowly, whereas Late Blight (caused by the Phytophthora fungus) may kill plants within a week. The fungus is always growing somewhere and releasing spores into the air, which moves on wind currents.
There are other disease and pest problems that may be affecting your crop, such as Verticillium wilt and Fusarium wilt.
When choosing tomato varieties, look for the words "disease-resistant" or the letters V (verticillium), F (fusarium), N (nematodes), T (tobacco mosaic), and A (alternaria). Some of the most disease-resistant varieties include Celebrity, SuperTasty, and Big Beef. Burpee's roma-type, 'Viva ItaliaHybrid', is resistant to Verticillium, Fusarium, Nematodes, and Bacterial Speck. As far as I know, there are no varieties resistant to the late blight fungus (Phytophthora).
If you follow the above practices every year, and choose resistant varieties, I'll bet the incidence of all disease will drop. Good Luck!