The tomato plant has one or both of the common plant diseases early blight (Alternaria solani Sorauer) and Septoria leaf spot (Septoria lycopersici). These diseases are soil-borne and common where tomatoes are grown. There are a number of cultural practices that will reduce the level of these diseases in tomatoes:
1. Use crop rotation (five years) where no other members of the tomato family are planted to reduce inoculum (disease) levels.
2. Select disease-resistant varieties when possible.
3. Grow tomato plants in a cage or on a trellis to get plants off the ground.
4. Water only when needed in the morning to allow foliage to dry prior to evening.
5. Fertilize appropriately.
6. Mulch under plants with compost.
Finally, there are fungicides available that, if used at the right time and with coverage on both sides of the leaf, may offer some aid in reducing these tomato diseases. Contact your local Extension office for fungicide recommendations.
