Tomato Troubles

For several years I have tried to stick to organic gardening, but I have trouble with my tomatoes. They always do great until late July and August. the leaves start drying up and falling off. Before long, the whole vine dies. I always put out the most disease-resistant types. Is there any organic remedy for this problem?

First, continue using varieties that are resistant to as many diseases as possible while balancing choices with your taste preferences. Now is the time to buy seeds.

Your tomatoes are victims of Septoria leaf spot, a fungus that is worst in warm, humid weather. Right now, resistant varieties do not exist. The disease overwinters in the soil; but to keep it from building up, pick off infected leaves as they appear, and make sure you never let dead plants stay in the garden.

The best organic treatment is to spray the plants with a solution of baking soda. A good overview is available from the National Sustainable Agriculture Information Service at www.attra.org/attra-pub/bakingsoda.html.

Several recipes are available. One calls for four teaspoons baking soda, one teaspoon vegetable oil and one-half teaspoon liquid detergent. There is also a ready-made baking soda product called Remedy. Gardener Supply Company carries the product. Call 1-888-833-1412, or visit www.gardeners.com.

Begin spraying before the disease appears so that the fungus never gets a chance to take hold. Obviously, you'll need to do this regularly and repeat immediately after rain. Avoid overhead watering as well.

Also consider planting a new crop of tomatoes for fall. The younger, vigorous plants could fare better against the disease.