The Occurrence Mechanism and Control Methods of Bottle Gourd Fruit Spot Disease

Bottle gourd, aliases: sweet gourd, sweet bottle gourd, bottle gourd, Jingjie chui, Longmi melon, Tian gua, long gourd, flat gourd; phylum Angiospermae, a species under the genus Lagenaria in the family Cucurbitaceae, a variety of the genus plant bottle gourd (Lagenaria siceraria), an annual climbing herb. It differs from the bottle gourd (original variety) in that: the ovary is cylindrical; the fruit is uniform in thickness and cylindrical, straight or slightly curved, up to 60-80 cm long, greenish-white, with white flesh. When young, the fruit is soft and juicy and can be used as a vegetable. It is cultivated in most parts of the country, widely cultivated in the Yangtze River basin area, and harvested in summer and autumn.

Bottle gourd has strong growth vigor, a large amount of stem and leaf growth, and bears many fruits, requiring a relatively large amount of water throughout the growing period. Bottle gourd requires soil with good aeration and rich in organic matter, and avoids continuous cropping. It grows well on fertile, loose sandy loam with convenient drainage and irrigation. Planting bottle gourd in heavy clay soil or low-lying land makes it prone to disease. During the growing period, a certain amount of nitrogen fertilizer is required, and during the fruiting stage it prefers sufficient phosphorus and potassium fertilizer. In the early growth stage it prefers a humid environment, and during the flowering and fruiting stage the soil and air humidity should not be too high.

What is bottle gourd fruit spot disease?

Bottle gourd fruit spot disease mainly damages the fruit. The lesions on the fruit are round or nearly round, 4-8 mm in size, brown to dark brown, without a margin. When they occur frequently, they often merge with each other to form large diseased patches, after which many small black granular dots appear on the diseased part, namely the pathogen's pycnidia. It is called Phoma subvelata, a fungus of the subphylum Deuteromycotina. The pycnidia are clustered, breaking through the epidermis, spherical or flattened spherical, with a membranous dark brown wall, 144-220 micrometers in size; the conidia are cylindrical, occasionally oblong, single-celled, colorless and transparent, straight or slightly curved, with 2 oil globules, 6-8 × 2-2.5 micrometers in size. The pathogen overwinters on diseased residues, and the following year spreads via wind and rain, invading through wounds or lenticels, causing fruit spot disease. In production, when water and fertilizer conditions are poor, management is inadequate, and growth is weak, the plant is susceptible to the disease.

Control methods for bottle gourd fruit spot disease:

(1) Before planting, apply sufficient fully decomposed organic fertilizer. During the growing period, generally do not apply quick-acting nitrogen fertilizer as a top dressing. During the seedling stage, loosen the soil and weed in time to promote root development. After the vines spread, press and coil the vines in time.

(2) Watering should be less rather than more, and drain promptly after rain.

(3) Carry out crop rotation with cucurbit crops for more than 3 years, pay attention to choosing high and dry plots or adopting high-ridge cultivation, clean the field promptly after harvest, and remove diseased gourds promptly when found and bury them deeply in a centralized manner.

(4) At the early stage of the disease, begin spraying 30% Ludebao suspension concentrate at 400 times dilution, or 25% copper amine complex aqueous solution at 500 times dilution, 47% Jiareinong wettable powder at 800 times dilution, 1:0.5-1:240 Bordeaux mixture, or chloramphenicol at 4000-5000 times dilution, once every about 7 days, for 2-3 consecutive treatments. Stop using the pesticide 3 days before harvest.