Cucumber Common Diseases and Control Methods in Family Gardening
Article Guide: This article covers the topic of cucumbers in the context of family gardening, focusing on common diseases and their prevention and control methods. A comprehensive introduction follows.
I. Cucumber Downy Mildew
Symptoms: The disease can occur at any stage, primarily affecting the leaves. The lower surface of the leaves shows watery, light yellow spots that gradually expand to form angular yellow patches. Under humid conditions, a gray-black mold layer may develop on the back of the spots, and the affected leaves develop from the bottom up, causing the entire plant to wilt severely.
Transmission and Incidence Conditions: The disease is spread by wind and rain. High humidity is a key condition for the occurrence of cucumber downy mildew. The pathogen requires water droplets or films for germination and infection. Dry leaf surfaces cannot germinate and die within 2-3 days. Poor ventilation, excessive humidity, poor temperature regulation, and significant temperature differences between day and night can easily cause water droplets or films on the leaf surface, leading to disease. The optimal temperature for the pathogen is between 15-22°C; higher temperatures make it less likely to cause disease. In the presence of water, temperature is the main factor determining the timing and severity of the disease.
Control Methods
1. Select new disease-resistant varieties, such as Jin Yan 4, Jin Chun 2, Jin Za 2-4, Changchun Mi Ci, and Shandong Mi Ci.
2. Strengthen cultivation management, use raised bed mulching technology, water under the mulch, reduce watering frequency. Enhance ventilation to lower air humidity. Apply phosphorus and potassium fertilizers to improve disease resistance. Remove lower old yellow leaves after fruiting. Spray 0.2% potassium dihydrogen phosphate or a mixture of 1:1:100 urea and sugar solution to increase the total sugar content in functional leaves and improve physiological disease resistance.
4. Chemical control. At the beginning of the disease, the following agents can be used: ① 25% metalaxyl WP 800-1000 times solution. ② 90% dimethomorph WP 500-600 times solution. ③ 75% chlorothalonil WP 500-600 times solution. ④ 72% propineb WP 600-800 times solution. ⑤ 72% procymidone WP 600-1000 times solution. ⑥ 45% chlorothalonil smoke agent, 250 grams per mu each time. ⑦ 5% chlorothalonil or 5% validamycin dust agent, 1 kilogram per mu each time, applied every 7-10 days for 3 consecutive times.
II. Cucumber Powdery Mildew
Symptoms: The disease primarily affects the leaves. Initially, white powdery spots appear on the back and surface of the leaves, which expand to form large patches of white powdery substance, gradually turning grayish-white. The leaves turn yellow and dry up without falling off.
Transmission and Incidence Conditions: In protected cultivation areas, the disease can occur year-round, spreading by wind or rain. The optimal temperature for powdery mildew is 20-25°C; above 30°C or below 10°C, the pathogen is less likely to form. Higher humidity favors pathogen formation, but the pathogen can still form at relative humidity below 25%. The disease is common in dense plantings, excessive nitrogen fertilization, poor ventilation and sunlight, soil water deficiency, or excessive irrigation.
Control Methods
1. Select disease-resistant varieties, such as Jin Yan 2, 4, Jin Chun 2, 3, Jin Za 1, 4, Man Yuan Lu, Bi Chun, Chun Xiang, etc.
Protective fumigation disinfection. Before planting, use sulfur powder or chlorothalonil smoke agents for disinfection. For sulfur powder fumigation, use 0.13 kilograms of sulfur powder and 0.25 kilograms of sawdust per 55 cubic meters. If using chlorothalonil smoke agents, apply 250 grams per mu, placed in several spots and ignited at dusk, then sealed overnight, opening the windows and doors the next morning for ventilation.
2. Strengthen fertilizer and water management, ensure ventilation and sunlight, prevent plant lodging and premature aging.
3. Chemical control. Use 40% fludioxonil EC 8000-10000 times solution, or 25% triadimefon WP 1500 times solution, or agricultural抗生素 120 biological agent 100PPm, or 50% carbendazim WP 600-800 times solution spray, alternating use, every 7-10 days for 2-3 consecutive times.
III. Cucumber Grey Mold
Symptoms: The disease primarily affects the flowers and young fruits of cucumbers, as well as leaves and stems. The pathogen usually starts infecting from the flowers, forming a gray-brown mold layer on the affected flowers, which then infects the young fruits, causing top rot. The affected young fruits initially appear waterlogged and discolored, then gradually rot and develop a gray-brown mold layer. Diseased flowers and fruits that fall on healthy stems and leaves can cause them to become infected. Leaf spots are watery and then become light brown, sometimes producing a brown mold layer in the center of the spots. Stem infection can cause the affected area to rot, and severe cases can lead to the death of the entire plant.
Transmission and Incidence: The pathogen overwinters in diseased residues and soil, spreading through wind, water, and agricultural operations. Diseased flowers and fruits can spread the disease again. The disease spreads under conditions of about 20°C, insufficient sunlight, high humidity in protected areas, poor ventilation, relative humidity above 90%, and prolonged dew. If the temperature is above 30°C or relative humidity is below 90%, the disease stops spreading.
Control Methods
1. Strengthen cultivation management, enhance lighting, improve ventilation, water under the mulch, avoid watering on cloudy days, and prevent excessive humidity.
2. Clean the field, promptly remove diseased flowers, fruits, and leaves and destroy them off-site.
3. Chemical control. At the beginning of the disease, use 10% procymidone smoke agent or 45% chlorothalonil smoke agent, 250 grams per mu each time, fumigated for 3-4 hours. Dust agents can also be used in the evening, such as 5% chlorothalonil or 6.5% metalaxyl dust agent, 1 kilogram per mu each time. Alternatively, use 50% procymidone WP 2000 times solution, or 50% iprodione WP 1500 times solution, or 75% chlorothalonil WP 600 times solution. Apply every 6-7 days for 3-4 consecutive times, ensuring the spray reaches the flowers and young fruits. Adding 0.1% of the 50% procymidone WP or 50% iprodione WP to the flowering stage significantly improves the effect.
The above introduces the methods for preventing and controlling common diseases of cucumbers in family gardening, which can be used as a reference for everyone.