Preventing tomato plant disease
Other than making sure your tomato plants are happy and healthy, there are a few other things you can do to help prevent tomato plant diseases. Here are nine tips to get you started on the road to disease-free, productive tomato plants:
- Rotate your crops. Since many tomato pathogens live in the soil, plant tomatoes in a different spot in the garden each year.
- Pinch off leaves with any signs of disease immediate and dispose of them in the trash to keep a possible infection from spreading.
- Don’t work in the garden when tomato foliage is wet or you may inadvertently spread pathogens from plant to plant.
- Choose disease-resistant varieties when selecting which types of tomatoes to grow.
- Remove all diseased tomato plant debris at the end of the growing season and burn it or toss it in the trash. Do not put diseased foliage in the compost pile.
- Provide adequate air circulation around each plant. Here’s our guide to spacing tomatoes properly.
- Mulch your tomato plants well at the start of the season. Two or three inches of compost, leaf mold, straw, or hay serves to keep soil-dwelling fungal spores from splashing up onto the lower leaves when it rains.
- Try to keep the foliage dry whenever possible. Hand irrigation or soaker hoses allow you to target the water on the root zone. The splash from overhead sprinklers can spread disease and wet foliage promotes fungal issues.
- Disinfect the empty pots if you grow your tomatoes in containers, using a 10% bleach solution at the end of the growing season and replace the spent potting soil with a new mix every spring.
Despite your best efforts at preventing tomato diseases, they may still get a foothold in your garden from time to time. Here’s the low-down on six of the most common tomato plant diseases with information on identifying, preventing, and managing each of them.
Identify: This common tomato plant disease appears as bulls-eye-shaped brown spots on the lower leaves of a plant. Often the tissue around the spots will turn yellow. Eventually, infected leaves will fall off the plant. In most cases, the tomatoes will continue to ripen, even as the disease symptoms progress up the plant.
Prevent: The early blight pathogen (Alternaria solani) lives in the soil and once a garden has shown signs of the early blight fungus, it’s there to stay because the organism easily overwinters in the soil, even in very cold climates. Fortunately, most tomatoes will continue to produce even with moderately severe cases of early blight. To prevent this tomato fungal disease, mulch plants with a layer of newspaper topped with untreated grass clippings, straw, leaf mold, or finished compost immediately after they are planted. This mulch forms a protective barrier, preventing the soil-dwelling spores from splashing up out of the soil and onto the plant.
Manage: Once the fungus strikes, organic fungicides based on Bacillus subtilis or copper can help prevent or stop the spread of this tomato plant disease. Bicarbonate fungicides are also effective (including BiCarb, GreenCure, etc).