Damping-off can be halted in seedlings
Earth Day is on Tuesday of this week — a signal to some gardeners to go ahead and start tomato seeds indoors. Vegetable gardeners in the Shenandoah Valley should start tomato seeds indoors now and transplant outdoors after May 15 when the danger of frost is past.
News Leader reader Don L. submits the following question: “How can I prevent my tomato seedlings from damping-off? I germinate the seeds in a small plastic container and then transplant them at about 4 inches tall into store-bought starter cups. They do well for a while but then start dying.”
Damping-off is the term used to describe the death of seedlings by fungal disease. This sudden plant death usually happens two to four weeks after seeds are started.
The fungi Pythium and Rhizoctonia cause damping-off in tomato seedlings. Research indicates these fungi can survive for years in typical garden soil. Symptoms of damping-off include sudden wilting or discoloration of the plants; seedlings falling over or bending at soil level; and low germination rates.
Defensive measures include:
• Ensure clean growing conditions. Always use sterile soil mixes to start tomatoes. Never use regular garden soil. If using recycled flats or containers for starting seeds, clean the containers with a solution of 10 percent bleach/90 percent hot water.
• If the seedling tray is covered with a plastic dome or baggie, ensure the container is not air tight. Adequate ventilation is critical for the prevention of damping-off.
• Water your seedlings with lukewarm water (room temperature). Water containers from the bottom rather than sprinkling from above. Avoid over-watering. Allow the surface of the soil to dry between waterings. The fungi responsible for damping-off are most active in cool, wet soils.
Other garden chores for late April include designing the layout of your vegetable garden. Always consider the amount of sunshine each area of the garden receives.
Leafy vegetables such as spinach and lettuce need at least six hours of direct sunshine. Fruiting vegetables, however, need a minimum of ten hours of full sun. These include tomatoes, squash, eggplant and peppers. Remember to check soil pH levels and add lime if necessary. Optimal soil pH for most vegetables is 6.0 to 6.5.
Contact Jeff Ishee at jeff@onthefarm radio.com.