How can I prevent diseases in tomato plants?
Written by
Liu Xiaohui
Reviewed by
Prof. Martin Thorne, Ph.D.Prevention of tomato diseases begins with smart cultural practices. Irrigating your plants only in the morning will keep the foliage dry. Space those plants 24-36 inches apart, and the airflow will help all plants stay dry. Rotating your crops every year specifically interrupts disease cycles. These 3 practices can prevent the most fungal and bacterial problems before they even start.
Cultural Controls
- Water before 10am to ensure leaf drying
- Stake plants for vertical growth and air circulation
- Remove lower leaves touching soil to prevent splashback
Treatment Protocols
- Apply copper fungicide at first sign of spots
- Use baking soda spray weekly for mildew prevention
- Remove infected plants immediately to contain spread
Morning watering is non-negotiable for disease prevention. I water my tomatoes at sunrise before I go to work. Leaves dry completely by noon. Evening watering leaves foliage wet all night, inviting mildew. Drip irrigation systems, on the other hand, water the roots, which keeps the leaves dry.
Proper Plant Spacing Saves Crops. Crowded plants trap moisture, creating environments conducive to disease. Allow 24 inches between plants for determinate varieties and 36 inches between plants for indeterminate varieties. Regularly prune suckers to promote airflow between plants. I stopped having mildew problems after I doubled plant spacing.
Copper fungicide interrupts infections early; mix as instructed on the label at the first sign of spots. Repeat spray every 7-10 days in humid conditions. Sprays of baking soda work preventively for organic gardens. Utilize in conjunction with cultural practices for optimal protection against troublesome diseases.
Crop rotation interrupts disease cycles. Never plant tomatoes in the same bed in consecutive years. Allow 3 years of space if nightshades have been infected. Grow resistant varieties like 'Defiant' and 'Mountain Magic', and clean tools between plants to prevent the spread of pathogens.
Read the full article: 8 Common Problems With Tomato Plants and Solutions
