Septoria leaf spot and early blight are common fungal leaf diseases of tomato. Cultural techniques can help reduce the risk of foliar blight outbreaks.
- Water and fertilize to maintain plants in a vigorous condition.
- Avoid fluctuations of too much and too little water.
- Avoid wetting foliage when watering. If overhead irrigation is used, water early in the day so the leaves dry quickly.
- Do not work with plants when the foliage is wet.
- Eradicate weeds. Mulching around plants can help reduce weed growth and prevent a certain amount of evaporation.
- Choose wilt-resistant varieties. Varieties that are resistant to Fusarium and Verticillium usually have the letters "VF" as part of the variety name.
- Fungicide applications can help to prevent fruit and leaves from fungal diseases, especially for gardens that have had a history of problems. Products that contain the active ingredient "chlorothalonil" are effective. Sprays should begin when the plants are about 12 inches tall and applied at 7 to 14 day intervals throughout the season. Using the proper rate and providing good coverage are important. Check the label to be sure it is labeled for tomato diseases and for proper rate information.
- At the end of the season, remove as much plant debris as possible and till under remaining debris. This helps reduce the overwintering of tomato pathogens.
This article originally appeared in the June 18, 1999 issue, p. 79.