There are a number of symptoms that may indicate your tomatoes are suffering from a fungal blight. Dark brown or black patches will appear on the plant's lower leaves and will quickly spread. These patches may be surrounded by a pale yellow ring. Stems will also develop dark spotting and streaks. At night, or in moist conditions, affected leaves will develop a coating of soft white spores. Leaves may also turn yellow and drop off the plant.
Blight will also be evident on the fruit of the plant. On immature fruit, dark markings will be visible. Ripe fruit will often develop brown scarring or rot, although this may not appear until after being harvested. An off-white mold may also be present.
Blight is most common earlier in the growing season. It can be brought on by damp conditions — if you live in a rainy or otherwise humid climate, you should be extra vigilant in protecting your plants.
How To Prevent Fungal Blight
Because tomato blight can spread quickly, taking preventative measures against fungal infection is preferable to treating an infected plant with tomato fungicide. Here are a few tips for preventing fungal blight in tomatoes:
Keep leaves dry: Because moisture encourages blight, be very careful when watering your plants. Water the soil directly rather than watering from overhead.
Give plants space: Allow at least 24 inches between plantings. Extra space increases airflow, which will allow tomatoes to dry faster when they get wet, preventing the spread of blight between plants.
Choose hardy varieties: Many varieties of tomato are bred to be blight-resistant. If you live in a humid or rainy climate, consider planting Ferline, Legend or other tomatoes resistant to blight. Always buy seeds from a dealer you trust.
When Blight Strikes
Identifying the problem early and taking quick action is the best way to help your plants recover from blight. Safer® Brand 3-in-1 Garden Spray is a sulfur-based organic fungicide for tomatoes that inhibits the growth of blight-causing funguses. Simply apply at the first sign of infestation and repeat every 7-10 days.
We also offer a special Tomato and Vegetable Care Kit, which packages our organic tomato fungicide with Safer® Brand Tomato and Vegetable Insect Killer. The entire Safer® Brand family of tomato fungicides and pest control is OMRI® Listed and USDA approved for use in organic gardening. Discover for yourself what a difference using a tomato fungicide of organic sulfur can make in your garden!