What are the methods for preventing and controlling lettuce black spot disease?
Lettuce is a vegetable whose stems and leaves can be eaten separately; some people like to eat the leaves, and some people like to eat the stems, and both taste very refreshing. Lettuce is grown in all regions and is easy to manage, but it is very susceptible to attack by diseases. In the lettuce growth process, the most common is black spot disease, so how should it be prevented and controlled?
1. How should lettuce black spot disease be prevented and controlled?
The pathogen of lettuce black spot disease usually appears in diseased plant residues in the soil, so it can safely survive the winter. Black spot disease infestation is generally more likely to occur in cloudy, rainy and humid weather, and once the disease occurs, the harm to lettuce is relatively great. In an environment with suitable temperature and suitable humidity, lettuce black spot disease easily produces spores for infection, and then spreads through wind and rain. It is especially prone to black spot disease when the soil fertility is insufficient or when lettuce growth is relatively slow and weak.
To prevent and control lettuce black spot disease, growers mainly need to strengthen field management work. When topdressing, choose organic fertilizer and phosphorus and potassium fertilizer, so that the disease resistance of lettuce can be improved. In addition, lettuce seed selection is also very key; generally, excellent varieties with no disease and strong adaptability should be selected. Before sowing, the seeds can be treated, so that the disease resistance of lettuce can be improved. Of course, the soil for growing lettuce is also very key, and crop rotation should be carried out. Usually, old leaves and diseased leaves should be removed in time and then deeply buried, so as to avoid infecting healthy plants. Once lettuce black spot disease is found, professional chemicals should be used for spraying treatment, and generally one course of treatment can achieve a very good effect.
2. Notes on lettuce cultivation
1. Choose suitable varieties
To achieve high lettuce yield, varieties suitable for local cultivation must be selected. For example, when growing lettuce in summer and autumn, try to choose early-maturing varieties that are drought-tolerant and heat-tolerant. If growing lettuce in winter and spring, try to choose varieties with good adaptability and cold resistance.
2. Determine the sowing time
For spring lettuce, the sowing time must distinguish whether it is greenhouse or open-field cultivation. For open-field cultivation, it is generally February to March, and for greenhouse cultivation, it is generally December to March. For summer lettuce cultivation, April to May is generally chosen. For autumn lettuce cultivation, July to September is generally chosen, sowing with shade net covering. For winter lettuce cultivation, sowing is generally in October to November.
3. Seed soaking and germination acceleration
If growing lettuce in summer, the temperature is very high, so we should choose cool water to soak the seeds before accelerating germination.
4. Sowing
Because spring, summer and autumn are different, the key points of lettuce cultivation also differ. For spring sowing, it is generally necessary to mix the seeds with some fine sand and then sow them in already moistened soil. For summer lettuce sowing, choose a cloudy day for sowing. For autumn lettuce sowing, remember to first water the seedbed thoroughly, then spread base fertilizer, and sow wet seeds.