There's nothing more frustrating than having tomato fruits set and start growing, only to see them develop cracks or catface, or rot on the vine. Fruit cracking is usually caused by fluctuating soil moisture conditions. A dry period followed by a heavy downpour stimulates the fruits to grow too quickly, causing the fruit to crack. This most often occurs on cherry tomatoes and older varieties. Keep the soil mulched and well watered to avoid moisture extremes.

Blossom end rot also is caused by fluctuating soil moisture conditions. In this case, the blossom end of ripening fruit rots before maturing. Fluctuating moisture causes a temporary calcium deficiency in the fruit. Calcium is transported by water and is critical to keeping cell walls strong. Again, mulching and regular watering will alleviate this condition.

Catfacing is a condition where cracks develop around the top of the fruit. It is mostly variety specific, so try modern varieties such as 'Carnival' that resist catfacing.

Tomato plants are susceptible to a number of foliar diseases. The symptoms of these diseases, such as early blight, septoria leaf spot, and bacterial speck, look similar. Often the disease starts as yellowing or brown spots on the leaves. The disease spreads, killing the leaves, and it may even attack the fruit. Other diseases, such as Verticillium wilt and virus, attack the whole plant at once, causing it to wilt and die when young. The key to controlling any tomato disease is prevention.

Rotate your crops each year to avoid soil-borne diseases. Some serious diseases can live in the soil for several years. Try to wait three years before planting tomatoes where they grew before. Also, avoid planting them where potatoes, eggplants, or peppers grew the previous season, because some diseases attack all these vegetables and live in the soil from year to year.

Plant resistant varieties, such as 'Big Beef' and 'Better Boy', that are resistant to Verticillium and Fusarium wilts. Most seed companies list resistance to these diseases by putting F (Fusarium) or V (Verticillium) after the variety name. N stands for resistance to nematodes, the tiny worms that plague many southern gardens, causing stunting of the plants and poor crops. Click here for more disease-resistant tomato varieties (www.willhiteseed.com/store/asp/prodtype.asp?prodtype=68).

Clean up the garden at the end of the season. Many disease-causing organisms spend the winter in plant debris in the soil. Destroy any obviously infected plant material rather than composting it.