Symptom Identification and Control Methods of Cucumber Late Blight

Cucumber is a functional vegetable with anti-tumor, anti-aging, anti-alcohol poisoning, blood sugar-lowering, brain-boosting and calming effects. Therefore, farmers who grow cucumbers all hope to achieve a high yield. However, during the cucumber growing process, pests and diseases often invade, such as cucumber late blight. So what symptoms does cucumber late blight have? How to control it?

1. What symptoms does cucumber late blight have?

Cucumber late blight causes damage to cucumber seedlings, starting from the edges of the cotyledons and true leaves and producing circular or irregular water-soaked lesions inward; in severe cases, the stem tip and each lateral bud show dark green water-soaked soft rot, and the leaves die. After the plant begins to vine, the disease occurs, and irregular water-soaked large lesions appear from the leaf margins inward, spreading rapidly. When the weather is humid, the lesions also expand very quickly, often causing the entire leaf to rot; when the weather is dry, the lesion edges are dark green and the centers are light brown, often drying out and becoming brittle and cracked.

2. How to control cucumber late blight?

1. Select disease-tolerant varieties, disinfect the seeds before sowing, and practice crop rotation with non-cucurbit crops for more than 5 years.

2. Use grafting to prevent disease.

3. Strengthen field management to improve the plant's disease resistance. Fertilize reasonably (especially nitrogen fertilizer), improve light penetration, open ditches in time for drainage, and reduce field temperature.

4. Chemical control. Before the disease occurs or before the rainy season arrives, spray a protective fungicide once. Starting from the seedling stage, spray 30ml of Shuangbeier mixed with 15kg of water, once every 5-7 days. For medication, you can spray 50ml of Shuangbeier + 15-20ml of garlic oil mixed with 15kg of water, once every 3-5 days.

3. Precautions for cucumber cultivation

1. Applying heavy chemical fertilizer while organic fertilizer. Some people think that the more chemical fertilizer, the higher the yield, so they blindly compete over chemical fertilizer amounts and apply little organic fertilizer, causing soil compaction, severe surface salinization, green moss forming on the surface, and in severe cases red moss forming. Root development is hindered in soil solution with high concentration, leaves age, vegetative growth is poor, and yield declines. Such greenhouses should increase organic fertilizer application and apply little or no chemical fertilizer to reduce fertilizer damage.

2. Using large amounts of diammonium phosphate during the fruiting period does not conform to the growth pattern of cucumbers. Topdressing notes: fruit-swelling elements: carbon, potassium, nitrogen, silicon, calcium, boron. 1. CO2; 2. Potassium fertilizer should use potassium nitrate type fertilizer; 3. Nitrogen fertilizer urea; 4. Silicon fertilizer spray 2 and flush 1, 4 times in a lifetime; 5. Calcium and boron elements have the fastest conversion effect through leaves, so foliar spraying for topdressing is recommended.

3. To lower the temperature, using straw mats to shade excessively. In the early planting stage, light intensity is high, and moderate shading to lower the temperature is acceptable, but excessive shading or shading in winter will cause insufficient light, affect flower bud differentiation, and reduce yield. Temperature should be lowered by ventilation.

4. Mixing multiple pesticides, with too high concentration and too much liquid. First, some agents undergo chemical reactions with each other, reducing efficacy. Second, many agents are compound pesticides and have already been mixed. Third, increased concentration means leaves are often soaked in high-concentration liquid, causing leaf function to decline, aging to accelerate, and photosynthesis to decrease.

5. No spraying when there is no disease, random medication when there is disease. Disease control should focus mainly on prevention, with treatment as a supplement. Applying medication in advance for prevention not only costs less but also has better results.