What are the causes of lettuce root rot and what are the control measures?
Lettuce likes a cool environment, and now is a good season for planting lettuce. However, during the lettuce seedling stage, many growers find that lettuce suffers from root rot, causing large numbers of lettuce seedlings to die. So what causes lettuce root rot? How should it be controlled? Let's take a look.
1. Symptoms of root rot
Root rot is extremely likely to occur when raising seedlings in low-temperature seasons. The disease onset is marked by no new roots or adventitious roots being produced at all, and the root bark turns rusty brown, gradually rotting and drying up. When the disease reaches a certain degree, the seedlings can easily be pulled out of the soil. In the early stage of the disease, the symptoms are not obvious, and the aboveground stems and leaves grow slowly. The leaves gradually turn yellow-green or milky yellow, and the leaf margins begin to turn withered yellow, until the entire leaf shrivels and turns withered yellow. The seedlings do not produce new leaves, and in severe cases the entire plant dies.
2. Causes of root rot
Because the soil temperature is below 12 degrees, the duration is poor, excessive watering, continuous rainy days, and insufficient light cause the seedling root system to be in a state of low soil temperature, excessive moisture, and lack of oxygen. The respiratory metabolism of the root system is blocked, normal growth and development cannot occur, and the root system's absorption capacity decreases, causing root rot. In addition, root rot can also occur when the soilless culture substrate has long-term water accumulation.
3. Control methods
When preparing the seedbed, ensure the soil is loose and level, so as to avoid water accumulation on the seedbed surface after watering, and ensure the seedbed has sufficient light. When sowing, it should be done finely and evenly, and the soil covering should not exceed 1 cm. Before sowing, water thoroughly to ensure enough bottom water. Throughout the seedling stage, watering should be controlled to avoid excessive moisture on the seedbed surface, especially to prevent the soil from being wet and shaded for a long time. 3-5 days before sowing, first cover with plastic film to raise the seedbed soil temperature, then remove the film and sow. If you sow without waiting for the low temperature to rise, the seeds will germinate more slowly. After emergence, ventilate at the proper time and in the proper amount, and strengthen the hardening of the seedlings. When planting at low temperature, water by hole, not by flooding irrigation, and fertilize evenly. After root rot occurs, you can cover with plastic film to raise the ground temperature, and loosen the soil in time to promote the diseased seedlings to produce new roots.
The above is an introduction to the causes of lettuce root rot and control measures. We hope it can help you. To learn more related knowledge, please follow us.