Scientific control of anthracnose of wax gourd

Benincasa hispida (Thunb.) Cogn.）For an annual herb, stems have tendrils, can climb tendrils, large leaves, open yellow flowers. Fruit spherical or long cylindrical, hairy and powdery surface, skin dark green or light green, is a relatively common vegetable. The skin and seeds can be used as medicine. Melon shape such as pillow, also known as pillow melon, produced in summer. Thermophilic and heat-resistant, high yield, storage and transportation resistance, winter and autumn appear more likely, planning in vegetable varieties. Green melon tender hair, mature hair cyan, thick skin powder, melon fat white. The flesh is called melon practice, and the seeds in the flesh are called melon rhinoceros, arranged to grow. Wax gourd is native to southern China and India and is now widely cultivated in East and South Asia. It can be used to cook soup, and can be fried. And it also has weight loss, lung function, can eliminate body edema. Wax gourd points skin surface has thorn and surface does not have thorn two kinds.

The shape characteristic petiole of wax gourd is stout, grow 5-20 centimeters, the surface has russet bristle and villous. Leaf blade reniform suborbicular, 15-30 cm wide, 5-7-lobed or sometimes cleft, lobes broadly triangular or ovate, apex acute, margin denticulate, base deeply cordate, curved open, suborbicular, 2.5-3.5 cm deep and wide. Leaf surface dark green, slightly rough, sparsely pilose, gradually falling off after aging, becoming nearly glabrous. abaxial surface scabrous, gray-white, hirsute, veins slightly raised on abaxial surface of leaf, densely hairy. Tendrils 2-3-branched, hirsute and villous. Monoecious, flowers solitary. Male pedicels 5-15 cm long, densely yellow-brown pubescent and villous, often with a bract at base of pedicel. bracts ovate or broadly oblong, 6-10 mm long, apex acute, pubescent. Calyx tube broadly campanulate, 12-15 mm wide, densely setose villous, lobes lanceolate, 8-12 mm long, serrate, reflexed. Corolla yellow, radial, lobes broadly obovate, 3-6 cm long, 2.5-3.5 cm wide, sparsely pilose on both surfaces, apex obtuse, 5-veined. Stamens 3, free, filaments 2-3 mm long, base inflated, hairy, anthers 5 mm long, 7-10 mm wide, anther cells 3-fold. Female pedicel less than 5 cm long, densely yellow-brown hirsute and villous. Ovary ovate or cylindric, densely yellow-brown velutinous hirsute, 2-4 cm long. Style 2-3 mm long, stigma 3, 12-15 mm long, 2-lobed. Fruit long terete or subglobose, large, hirsute and glaucous, 25-60 cm long, 10-25 cm in diam. Seeds ovate, white or yellowish, compressed, margined, 10-11 mm long, 5-7 mm wide, 2 mm thick. Colletotrichum gloeosporioides is one of the main diseases of wax gourd, which seriously endangers the production of wax gourd and reduces the benefit of wax gourd planting. So how to scientifically control Colletotrichum gloeosporioides? Colletotrichum gloeosporioides can damage cotyledons, true leaves, petioles, main vines and fruits, and fruit symptoms are the most obvious, but also the most harmful. Colletotrichum gloeosporioides infection occurs mostly at the top of wax gourd fruit. The symptoms initially appear as water-soaked spots, then gradually expand, showing round brown concave spots. Pink granules grow in the spots when humidity is high, which is one of the most obvious symptoms of the disease. When seriously ill, the skin of melon turns brown and rotting, causing wax gourd to lose its commodity value. The disease spots on the leaves are round, brown or reddish brown, surrounded by yellow halo, and the central color is light. The size of the lesion varies greatly, with more lesions 8--10 cm in diameter. The disease spots often cause the leaves to dry up. Anthracnose mainly damages leaves, stems and fruits. Fruit infected from the base near the beginning, initially dark green water stains, then turn black brown, slightly sunken, humidity when the disease spots can be seen sticky matter or glue flow. The disease spots on leaves are round and yellow-brown, the boundary of disease and health parts is not obvious, and yellow halo is around the disease spots. Petiole and vine spots oblong or fusiform, brown slightly concave, amber when wet glue, spots around the vine after a week will appear infected parts shrink, more than the affected part died. Colletotrichum gloeosporioides is caused by a fungus called Colletotrichum cucurbitae. Mycelia or pseudosclerotia overwinter with the diseased bodies in the soil and produce conidia in the following spring, which spread to melon or plant with wind and rain or irrigation water for infection. Seeds can also carry bacteria, which infect cotyledons first after emergence and produce spores for repeated infection. The disease occurs most seriously at about 25℃ and relative humidity of 90%--95%, and the best condition is when planting melon in spring. If the vine grows too dense, the permeability is poor, the field drainage is easy to cause the disease, and the disease will also occur during transportation and storage after harvest. The control of Colletotrichum gloeosporioides should be carried out from the following aspects: 1. Select disease-free plants to keep seeds, and disinfect seeds before sowing. Soak seeds in warm water at 55℃ for 15 minutes and then cool, or soak seeds in 40% formalin 150 times for 15 minutes, and then soak seeds in clean water for germination. 2. Implement rotation with non-melon crops. Attention should be paid to eliminating accumulated water in the field and reasonably planting vines closely to ensure inter-plant permeability and reduce humidity during melon fruiting period. And rational formula fertilization, improve disease resistance. 3. Pay attention to spraying when the leaf spots appear, to prevent the bacteria from infecting the fruit, especially in the early stage of the melon, to prevent early control. The selected pesticides include: 800--1000 times of Aijuntuo (70% wettable powder); 600--800 times of Lunduo Ke (45% wettable powder) or Dashuangning (75% wettable powder); 1000--1500 times of myclobutanil (12--5% EC). Choose one of the above agents every 7- 10 days, spray 2- 3 times.