Bacterial wilt strikes tomato plants with little warning.
Bacterial wilt is a devastating garden disease, causing tomatoes and other nightshade vegetable plants to wilt and die suddenly and with very little warning. Bacterial wilt is nearly impossible to treat, but there are steps you can take to prevent its spread. Here’s what you need to know about bacterial wilt in the garden.
About Bacterial Wilt
Bacterial wilt is a soil-borne disease caused by the bacteria Ralstonia solancearum. It targets primarily tomatoes but is also a problem for potatoes, peppers, eggplant, sweet potatoes, bananas, and many weeds (which act as hosts).
Bacterial wilt can be identified by:
Testing for bacterial wilt.
- Warning signs: The plant may start to look wilted in the mornings but then perk up over the course of the day.
- Sudden death: The entire plant can suddenly wilt and die in a matter of hours.
- Stem rot: The stem may rot from the inside out, revealing a brown or hollow center.
- Field test: To test to see if your plants have bacterial wilt, cut a chunk of the main stem, about 2-3 inches long. Suspend it in a glass of water. Within a few minutes, you should see milky white bacteria flowing out of the stem.
Bacterial wilt may be encouraged by:
- Injured plants, since the bacteria enters the roots through wounds caused by cultivation, improper planting, and nematodes or other root-feeding critters in the soil.
- Poorly draining, infertile, or heavy clay soil.
- Acidic soil.
- Hot, humid or rainy conditions.
- Soil infected with the bacteria. Bacterial wilt can live for years in soil without a host plant present.
- Water runoff that spreads the bacteria.
- Weeds that can act as hosts to the bacteria without showing symptoms of bacterial wilt.
- Infected tools, transplants, and imported soil.
Other wilts, such as fusarium wilt and verticillium wilt, are caused by soil-borne fungus and can also attack tomato plants. Unlike bacterial wilt, both of these fungal wilts begin with yellowing of the leaves and don’t kill the plant quite as suddenly as bacterial wilt.
Treatment and Prevention
If you suspect bacterial wilt in your garden (and even if you don’t), follow these tips to prevent its spread:
- Remove Infected Plants and Soil: Immediately remove and burn any affected plants before the bacteria are released back into the soil. To be safe, dig out the soil around the plants too, rather than pulling them and leaving infected root fragments behind.
- Plant in Containers: Planting in containers or raised beds allows better control over the soil and drainage.
- Rotate Crops: Practice crop rotation to keep plants away from the same spot for at least three years.
- Control Nematodes and Soil Insects: If control isn’t possible, avoid planting susceptible plants in infested areas.
- Minimize Injury: Don’t over cultivate plants, and be very careful not to damage roots.
- Improve Soil: Make sure your soil drains well and is full or organic matter, with a pH of at least 5.5.
- Garden Smart: Work in infested areas last, then disinfect implements immediately afterward with bleach. This includes tools, tiller, gloves, even the soles of your shoes!
- Keep Garden Weeded: Eliminate weeds from your garden, since they can act as hosts to bacterial wilt.
- Disinfect Soil: If you’re starting seeds or transplants, use pasteurized soil. You can also try solarizing your garden soil, although this has shown limited results with bacterial wilt.
- Graft Plants: If you’re adventurous, you can graft your tomato seedlings onto resistant eggplant rootstock.
- Plant Resistant Varieties: A few varieties of tomatoes are somewhat resistant to bacterial wilt, but it’s touch-and-go. Check with your local agricultural extension service to find out if any varieties are working in your area.
- Tomatoes: Wilt (Penn State University)
- Bacterial Wilt (AVRDC Fact Sheet)
- Tomato Bacterial Wilt (LSU, helpful diagnostic photos
- Tomato Wilt Problems (University of Tennessee Extension)
- How To Grow Tomatoes
- Tips for Growing Tomatoes (video)
- How to Grow Tomatoes in the Deep South
- How to Keep Tomatoes from Splitting Open
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