Symptoms and prevention methods of loofah anthracnose

When we grow loofah, various diseases will appear. So how can we better prevent them? Anthracnose of loofah is very serious. Here are the symptoms and how to prevent it:

(1) Symptoms of Anthracnose in Luffa

It can occur in all growth stages, with more severe cases in the middle and late stages of growth. When the seedlings are infected, brown semicircular or circular lesions appear on the edges of the cotyledons, the base of the stems is affected, the affected parts are constricted, discolored, and the seedlings fall off suddenly. When the disease occurs in the adult stage, the lesions on the stems and petioles are oblong, slightly sunken, initially water-soaked, light yellow, and then dark brown. When the lesions ring the stems, vines, and petioles for a week, the upper part will die. When the leaves are affected, small water-soaked spots appear at first, and then expand into nearly circular lesions, reddish-brown, with a circle of yellow stripes on the outside. When there are many lesions, they merge into large irregular patches. Under dry conditions, the middle of the lesions ruptures to form perforations, and the leaves dry up and die. In the later stage, small black spots appear on the lesions, and red sticky substances grow when it is humid. When the fruit is infected, the lesions are initially light green, and then turn into dark brown sunken spots, with small black spots in the middle of the lesions. When the disease is humid, pink sticky substances appear on the lesions. Under dry conditions, the lesions gradually crack and reveal the flesh. When the disease is serious, the whole plant will die.

(2) Conditions for the occurrence of loofah anthracnose

Anthracnose is a fungal disease caused by the fungus of the genus Colletotrichum of the subphylum Ascomycetes. The pathogen overwinters in the remains of diseased plants or in the soil as mycelium and pseudosclerotia, or on the epidermal mucosa of seeds. In addition, the pathogen can also live a saprophytic life on old wood in greenhouses and sheds. The next year, it spreads through seeds, irrigation, wind and rain, insects, etc. Conidia can germinate directly from the epidermis or wounds to invade.

The optimum temperature for the spore germination of the pathogen is 22-27℃, and the optimum temperature for the growth of the pathogen is 24℃. It stops growing when the temperature is above 30℃ and below 10℃. The disease requires a relatively high air humidity. When the humidity is as high as 87%-95%, the disease will occur rapidly. When the humidity is less than 54%, the disease will not occur. In addition, the disease is serious in low-lying areas, poor drainage, excessive density, excessive nitrogen fertilizer, poor ventilation, excessive irrigation, and continuous cropping.

(3) Prevention and control methods of loofah anthracnose

① Different varieties have different endurance.

② Leave seeds in disease-free areas, disease-free fields, or disease-free plants to prevent seeds from being infected. Seeds should be disinfected before germination to eliminate the bacteria they carry. Common methods include: warm soup seeds: soak seeds in 55°C warm soup for 15 minutes, then move them into cold water for germination.

Seed soaking with chemicals: soak the seeds in 100 times diluted formalin for 30 minutes, then wash and germinate; or soak the seeds in 100 times diluted glacial acetic acid for half an hour, wash with clean water and then germinate.

③ Rotation with non-melon crops should be carried out for more than 3 years.

④ Soil treatment Use disease-free field soil to grow seedlings, or use pesticides to disinfect the soil in the seedbed. Generally, use 50% carbendazim or 50% anthracnose fumei, 8 grams per square meter, and mix with the surface soil. You can also use the summer greenhouse method to raise the soil temperature to above 50℃ to eliminate pathogens. When conditions permit, the use of soilless seedling technology is the best.

⑤ Cultivation and management Choose high and dry sandy loam with convenient drainage for cultivation. Apply sufficient basal fertilizer, and increase the application of phosphorus and potassium fertilizers; drain in time during the rainy season; in the protected area, close the greenhouse in the morning to raise the temperature to 30-34℃, and strengthen ventilation in the afternoon to reduce the humidity in the greenhouse to below 75%, creating an environment that is not conducive to the occurrence of diseases; clean the fields in time, remove the remains of diseased plants, and bury or burn them. The above measures can reduce the occurrence of diseases.

⑥ In the early stage of disease control, you can use 600 times of 75% thiophanate-methyl wettable powder, 500-700 times of 50% thiophanate-methyl wettable powder, 500-700 times of 50% carbendazim wettable powder, 500 times of 65% mancozeb wettable powder, 1,000 times of 50% mancozeb, 400 times of 50% anthrax thiram, or 200 times of agricultural antibiotic 120. One of the above drugs, once every 6-7 days, for 4-5 times in a row.