Control of Colletotrichum gloeosporioides in Greenhouse Cultivation of Colletotrichum chinense

Gourd seed (pinyin: hü z), alias: Ganhu, sweet gourd, gourd, Jingjie hammer, Longmi melon, Tiangua, Changhu, flat pu; Angiosperm phylum, a species of gourd belonging to Cucurbitaceae, a variety of gourd belonging to this genus, an annual climbing herb.

Morphological characteristics of gourd seeds

Annual climbing herbs; stems and branches grooved, mucilaginous villous, decrescent with age, becoming subglabrous. Petiole slender, 16-20 cm long, with branch-like indumentum, 2 glands at tip; leaf blade ovate-cordate or reniform ovate, 10-36 cm long and wide, undivided or 3-5-lobed, with 5-7 palmate veins, apex acute, margin irregularly toothed, base cordate, curved open, semicircular or subrounded, 1-3 cm deep, 2-6 cm wide, puberulent on both surfaces, densely densified on leaf back and veins.

Tendrils slender, puberulent at first, glabrescent, glabrous, upper part 2-branched. Monoecious plant, female, male flowers are solitary. Male flowers: pedicel fine, slightly longer than petiole, pedicel, calyx, corolla are puberulent; calyx tube funnel-shaped, ca. 2 cm long, lobes lanceolate, 5 mm long; corolla yellow, lobes corrugated, 3-4 cm long, 2-3 cm wide, apex emarginate and apiculate, 5-veined; stamens 3, filaments 3-4 mm long, anthers 8-10 mm long, oblong, anther cells folded. Female pedicels slightly shorter or subequal than petioles; calyx and corolla similar to male flowers; calyx tube 2-3 mm long; ovary middle constricted, densely mucilaginous villous, style stout, stigma 3, dilated, 2-lobed.

The fruit is green at the beginning, then white to yellow, due to long-term cultivation; the fruit shape varies greatly, because of different varieties or varieties, some are sub-bell-shaped, the middle is constricted, the lower part and the upper part are expanded, the upper part is larger than the lower part, dozens of centimeters long, some are only 10 centimeters long (small gourd), some are flat spherical, rod-shaped or structured, and the pericarp becomes woody after maturity. Seeds white, obovate or triangular, apex truncate or 2-dentate, sparsely rounded, ca. 20 mm. Flowering summer, fruiting autumn.

The growing environment of gourd

The bottle gourd has strong growth potential, large stem and leaf growth, many fruits, and a large water requirement during the whole growth period. Calabash requires good permeability, rich in organic matter soil, avoid continuous cropping. It grows well on fertile loose sandy loam with convenient irrigation and drainage. Colla fruticosa is susceptible to disease when planted in heavy clay soil and low-lying land. A certain amount of nitrogen fertilizer should be supplied during the growth period, and sufficient phosphorus and potassium fertilizer should be supplied during the fruiting period. The humidity of soil and air should not be too high during flowering and fruiting period.

Control of Colletotrichum gloeosporioides in Greenhouse Cultivation of Colletotrichum chinense

Symptoms of Colletotrichum gloeosporioides

The seeds of bottle gourd are infected with bacteria. After sowing, under the condition of low temperature and high humidity, it takes a long time for cotyledons to emerge. It often appears that cotyledons have just emerged and have not yet unfolded. Light brown to brown spots appear on the edges of cotyledons or cotyledons. After expansion, they are slightly depressed. Pink sticky substances grow on them when humidity is high. Colletotrichum gloeosporioides can also occur in adult plant stage, mainly damaging fruits. Fruit spot round or nearly round, 2~6 mm in size, light green at the beginning, black brown later, slightly depressed, humidity, disease part densely yellow punctate sticky matter, disease spots often fused into large spots or single visible. At the end of autumn, small black spots arranged in concentric rings grow on the spots. The neck is infected, and the fruit is mostly immature, hanging on the plant or falling off.

Pathway of Transmission and Condition of Occurrence of Colletotrichum gloeosporioides

The fungus overwinters in the soil as mycelia, pseudosclerotia on seeds or residues. After sowing, the mycelium latent on the seed can directly invade the cotyledon, causing the cotyledon disease, planting the diseased seedling, the conidia produced by the diseased part spread by rain splash, forming the disease center, the disease can be caused at 10~30℃ in the greenhouse, and the disease is serious at 24℃. The high humidity during the seedling period is an important condition for inducing the disease. The relative humidity is 87%~98% and the temperature is 24℃. The disease can be seen after 3 days incubation. The relative humidity is lower than 54%. In early spring, the temperature of plastic shed is low, the humidity is high, the gourd spits water and the leaf surface dews, and the leaf surface has water drops, which can meet the humidity conditions of the disease, causing the occurrence of seedling anthracnose.

The control method of Colletotrichum gloeosporioides:

1)Seed treatment. Firstly, disease-free seeds are selected, seeds are collected from disease-free gourds, seeds for production are soaked in warm water at 50 - 51 DEG C for 20 minutes or soaked in glacial acetic acid for 100 times for 30 minutes, and then are washed clean with clean water and germinated.

2)Nursery land should be rotated for more than 3 years to prevent soil bacteria, and seedbed soil disinfection must be carried out when rotation is not possible.

3)At the early stage of disease, spray 25% Tanteling WP 500 times solution or 50% Thiophanate-methyl-sulfur suspension 800 times solution, 50% Shibaogong WP 1000 times solution and 50% Duofengnong WP 500 times solution in greenhouse or open field.

4)500 times solution of 80% Dasheng wettable powder and 8% Ketanling dust can be sprayed in greenhouse, every 667m21kg, once every 7~10 days, for 2~3 times of continuous control.

5)Select disease-free seeds and anthracnose resistant gourd seeds, gourd varieties.

6)Strengthen ventilation and temperature and humidity management to keep them away from disease conditions.