Latest Technical Method Tutorial for the Prevention and Control of Cucumber Anthracnose
In recent years, cucumber anthracnose has become increasingly severe, and it is caused by the fungi carried on imported seeds. It occurs in both spring and autumn, is difficult to control, and has a huge impact on production.
Symptoms of cucumber anthracnose
Cucumber anthracnose can occur from the seedling stage to the mature plant stage. When seedlings are affected, semi-elliptical light brown lesions usually appear on the edges of the cotyledons, bearing orange-yellow dotted gelatinous material; when mature leaves are infected, the lesions are nearly round, 4---18 mm in diameter, grayish brown to reddish brown, and in severe cases the leaves dry up; when stems and vines and petioles are infected, the lesions are elliptical or oblong, yellowish brown, slightly sunken, and in severe cases the lesions join together, encircle the stem, and the plant dies; when the fruit is infected, the lesions are nearly round, initially light green, later turning yellowish brown, slightly sunken, with pink sticky material on the surface, and cracking in the later stage.
The pathogen of cucumber anthracnose
Cucumber anthracnose is caused by infection by a fungus of the subphylum Deuteromycotina, Colletotrichum orbiculare (cucurbit anthracnose fungus). The pathogen overwinters as mycelium or sclerotium-like bodies on seeds or, along with diseased plant residues, in the soil.
Disease characteristics of cucumber anthracnose
When conditions are suitable in the following spring, the pathogen produces acervuli and a large number of conidia, which become the primary infection source. The pathogen spreads through wind and rain, irrigation water, and farming operations, causing secondary infection. Seed transport can cause long-distance spread. The optimum temperature for disease development in the field is 20-27°C, the optimum growth temperature for the pathogen is 24°C, and when the relative humidity of the air is above 95% and there are water droplets on the leaves, disease development is favored; under suitable temperature and humidity, the incubation period is only 3 days. In cucumber fields with clayey soil, poor drainage, excessive nitrogen fertilizer application, insufficient light in protected cultivation, and delayed ventilation, the disease is severe. In Zhejiang and the middle and lower reaches of the Yangtze River, cucumber anthracnose mostly occurs under protected cultivation, with peak disease periods in May-June and September-October.
Control measures for cucumber anthracnose
Starting from the seedling stage, spray 30 ml of "Sujing" diluted in 15 kg of water, once every 5—7 days. For treatment: spray 50 ml of "Sujing" + 15-20 ml of "Garlic Oil" diluted in 15 kg of water, once every 3—5 days, for 2-3 consecutive applications.
1. Low temperature and high humidity, poor ventilation and light transmission, humidity above 97%, and humidity around 22—27 degrees are when the disease is most prevalent; open-field cucumbers are prone to mixed infection with bacterial diseases.
2. Choose sandy loam soil with good drainage for planting, and avoid low-lying plots with poor drainage.
3. Spray with 150-200 times dilution of Nongkang 120 (pyrimidine nucleoside antibiotic); 600-800 times dilution of 70% mancozeb wettable powder; 800-1200 times dilution of 38% oxadixyl-cymoxanil-copper? (ethaboxam? no) — 38% oxadixyl, pyrimethanil and copper fungicide 800-1200 times dilution; 800 times dilution of 20% flusilazole and prochloraz; 600 times dilution of 56% azoxystrobin and chlorothalonil; 500-600 times dilution of 58% metalaxyl-mancozeb wettable powder; 600 times dilution spray of Pingfuxing (a fruit tree fungicide); 300 times dilution spray of a 1:1 mixture of 50% thiram wettable powder and 50% carbendazim wettable powder; 1000 times dilution of 50% Sportak (prochloraz) wettable powder.