What are the scientific control methods for anthracnose in winter melon?

Winter melon (scientific name: Benincasa hispida (Thunb.) Cogn.) is an annual herbaceous plant with tendrils on the stem, able to climb and vine, large leaves, and yellow flowers. The fruit is spherical or long cylindrical, with hairs and a white bloom on the surface, and the skin is dark green or light green; it is a relatively common vegetable. The skin and seeds can be used as medicine. The fruit is shaped like a pillow, so it is also called pillow melon, and it is produced in summer. It likes warmth and tolerates heat, has high yield, and stores and transports well; it appears more often in winter and autumn, and is classified among vegetable varieties. When young, the fruit is green and hairy; when mature, it turns bluish-green, with a hard, thick skin bearing a bloom, and the flesh is fat and white. The pulp is called gualian, and the seeds in the pulp are called guaxi, growing in rows. Winter melon originated in various parts of southern China and India, and is now widely cultivated in East Asia and South Asia. It can be used to make soup and can also be stir-fried. It also has weight-loss and lung-moistening effects, and can relieve body edema. Winter melons are divided into two types: those with prickles on the skin surface and those without prickles on the surface.

Morphological characteristics of winter melon The petiole is stout, 5-20 cm long, with yellow-brown stiff hairs and long soft hairs on the surface. The leaf blade is kidney-shaped and nearly circular, 15-30 cm wide, 5-7 shallowly lobed or sometimes moderately lobed, with lobes broadly triangular or ovate, the apex acute, the margin with small teeth, the base deeply cordate, the sinus open, nearly circular, both 2.5-3.5 cm deep and wide. The leaf surface is dark green, slightly rough, with sparse soft hairs, gradually falling off when old and becoming nearly hairless. The underside is rough, grayish-white, with coarse stiff hairs; the veins are slightly raised on the underside and densely hairy. Tendrils are 2-3 branched, covered with coarse stiff hairs and long soft hairs. Monoecious, flowers solitary. The male pedicel is 5-15 cm long, densely covered with yellow-brown short bristles and long soft hairs, often with a bract at the base of the pedicel. The bract is ovate or broadly oblong, 6-10 mm long, acute at the apex, with short soft hairs. The calyx tube is broadly campanulate, 12-15 mm wide, densely covered with bristle-like long soft hairs; the lobes are lanceolate, 8-12 mm long, serrate, and reflexed. The corolla is yellow, rotate; the lobes are broadly obovate, 3-6 cm long, 2.5-3.5 cm wide, sparsely soft-hairy on both sides, obtuse at the apex, with 5 veins. Stamens 3, free; filaments 2-3 mm long, swollen at the base, hairy; anthers 5 mm long, 7-10 mm wide; thecae curved in 3 folds. The female pedicel is less than 5 cm long, densely covered with yellow-brown stiff hairs and long soft hairs. The ovary is ovate or cylindrical, densely covered with yellow-brown downy stiff hairs, 2-4 cm long. The style is 2-3 mm long; stigmas 3, 12-15 mm long, 2-cleft. The fruit is long cylindrical or nearly spherical, large, with stiff hairs and white frost, 25-60 cm long, 10-25 cm in diameter. Seeds are ovate, white or pale yellow, compressed, margined, 10-11 mm long, 5-7 mm wide, and 2 mm thick. Winter melon anthracnose is one of the main diseases of winter melon, seriously harming winter melon production and reducing the benefits of winter melon cultivation. So how should winter melon anthracnose be scientifically controlled? Winter melon anthracnose can damage the cotyledons, true leaves, petioles, main vines, and fruits, with fruit symptoms being the most obvious and the damage the greatest. Infection of winter melon fruit by anthracnose mostly occurs at the top; the symptom initially appears as small water-soaked spots, then gradually expands into circular brown depressed spots, and when humidity is high, pink granular matter grows in the center of the spots, which is one of the most obvious signs of the disease. In severe cases, the flesh under the skin turns brown and rots, causing the winter melon to lose its commercial value. Leaf spots are circular, brown or reddish-brown, with a yellow halo around them, and the center is lighter in color. Spot size varies greatly, with spots 8--10 cm in diameter being more common. When there are many spots, the leaves dry up. Anthracnose of chieh-qua mainly damages leaves, stems and vines, and fruits. Fruit infection mostly starts near the fruit stalk, initially appearing dark green and water-soaked, then turning dark brown and slightly depressed; when humidity is high, sticky matter or gum exudate can be seen on the spots. Leaf spots are circular and yellow-brown, with an indistinct boundary between diseased and healthy parts, and a yellow halo around the spots. Spots on petioles and stems and vines are oblong or spindle-shaped, brown and slightly depressed; when moist, amber gum exudes, and after the spots encircle the vine, the affected part shrinks and the part above the affected area dies. Anthracnose of winter melon and chieh-qua is both caused by a fungus called Colletotrichum orbiculare. The mycelium or sclerotia overwinter with diseased residues in the soil, and in the following spring produce conidia that spread with wind and rain or irrigation water to the fruit or plants and infect them. Seeds can also carry the fungus; after emergence, it first infects the cotyledons, produces spores, and causes repeated infection. The disease occurs most severely at about 25°C and 90%--95% relative humidity, and the conditions are optimal for disease development when spring-planted crops set fruit. If the vines grow too densely, permeability is poor, and field drainage is poor, the disease is easily triggered, and it can also develop during transport and storage after harvest. Control of anthracnose in winter melon and chieh-qua should start from the following aspects: 1. Select disease-free plants for seed production, and disinfect seeds before sowing. Soak seeds in warm water at 55°C for 15 minutes and then cool, or soak in 40% formalin at 150 times dilution for 15 minutes, then soak in clean water for germination. 2. Practice crop rotation with non-cucurbit crops. Pay attention to draining accumulated water in the field and to rational close planting and vine training, ensuring permeability between plants during the fruit-setting period and reducing humidity. Also apply balanced fertilization to improve disease resistance. 3. Pay attention to spraying promptly when spots appear on leaves to prevent the pathogen from infecting the fruit; especially at the early fruit-setting stage, spraying must be done for early control. Optional agents include: azoxystrobin (70% wettable powder) at 800--1000 times; cymoxanil (45% wettable powder) or dimethomorph (75% wettable powder) at 600--800 times; myclobutanil (12--5% emulsifiable concentrate) at 1000--1500 times. Choose one of the above agents and apply once every 7--10 days, spraying 2--3 times in succession.