Common Diseases of Bitter Gourd and Their Control Methods

Bitter gourd has the effects of clearing heat and detoxifying, nourishing the skin, and nourishing the blood and liver, making it an excellent ingredient in summer. So, what are the common diseases of bitter gourd during cultivation, and how should they be controlled?

1. Damping-off Disease

Symptoms: Damping-off disease is most likely to occur shortly after the seedlings emerge. At first, the base of the young stem of the seedling takes on a water-soaked appearance, then the diseased part turns light brown, and the seedling is noticeably constricted near the ground, toppling over before the cotyledons have wilted. Low soil temperature and high humidity favor the growth and reproduction of the pathogen, so the disease is generally severe when nights are cool, daytime light is insufficient, and the seedbed humidity is high.

Control measures: ① Seedbed disinfection: before planting, use 70% quintozene and 50% thiram in the planting furrow for soil disinfection. ② Chemical control: spray the base of the seedlings with 72.2% propamocarb hydrochloride at 750 times dilution, or with Ling·mancozeb, or 58% metalaxyl·mancozeb, or 75% chlorothalonil at 600 times dilution, or 32% metalaxyl·hymexazol at 300 times dilution.

2. Anthracnose

Symptoms: The fruit, leaves, and stems can all be affected. The lesions on the fruit are round or irregular, initially pale yellowish-brown, later turning reddish-brown to light brown, and slightly sunken. The leaf lesions are round or irregular, grayish-brown to brownish, and slightly water-soaked. The stem lesions are oblong, brown, sunken, and sometimes cracked.

Control measures: ① Select disease-resistant varieties and disinfect the seeds. ② Rotate with non-cucurbit vegetables in heavily infested fields. ③ Avoid one-sided or excessive application of nitrogen fertilizer; increase phosphorus, potassium, and medium- and trace-element fertilizers, while appropriately controlling irrigation and draining accumulated water after rain. ④ Promptly remove diseased leaves, branches, and fruit, and keep the field well ventilated and well lit. ⑤ Chemical control: before the disease occurs, spray 25% prochloraz at 1500 times dilution for prevention; when the disease occurs, spray 10% difenoconazole at 1500 times dilution or 32.5% azoxystrobin·difenoconazole.

3. Brown Spot

Symptoms: It mainly affects the leaves. At first, small brown round spots appear on the leaves, then gradually expand into nearly round or irregular yellowish-brown spots, often surrounded by a chlorotic halo. When environmental conditions are suitable, the lesions rapidly expand and merge into patches, and eventually the entire leaf dries up.

Control measures: ① Choose plots with higher terrain and good drainage for planting. ② Promptly set up trellises, prune branches, and remove leaves to improve field ventilation and light penetration. ③ Base fertilizer should be mainly organic fertilizer; topdressing should combine nitrogen, phosphorus, and potassium, and foliar fertilizer for cucurbit vegetables should be sprayed. ④ Irrigate at the proper time, promptly drain field water after rain, and pay attention to controlling field humidity. ⑤ Implement crop rotation in heavily infested fields. ⑥ Chemical control is the same as for anthracnose.

4. Powdery Mildew

Symptoms: Leaves, petioles, and stems can all be affected. When leaves are affected, small white powdery spots initially appear on the upper and lower surfaces of the leaves, expanding into round or nearly round sparse white powdery patches; as the disease progresses, the powdery patches merge, covering the leaf surface with a thin layer of white powder. In severe cases, the leaves gradually turn yellow and finally dry up, hindering the growth and fruiting of the whole plant and greatly shortening the growth period. When petioles and stems are affected, the diseased parts are covered with sparse white powder.

Control measures: ① Select disease-resistant (tolerant) varieties. ② Plant at a reasonable density, promptly set up trellises, train the vines, and remove leaves to enhance plant ventilation and light penetration. ③ Use balanced fertilization and increase the application (spraying) of medium- and trace-element fertilizers. ④ Irrigate moderately and do not let the soil become too wet. ⑤ Chemical control: before the disease occurs, spray 32.5% azoxystrobin difenoconazole or chlorothalonil for prevention; after the disease occurs, alternately spray 10% difenoconazole at 1500 times dilution, or 80% sulfur dry flowable at 600 times dilution, or 25% triadimefon wettable powder at 1000 times dilution.

During its growth, bitter gourd may have to endure so many diseases; it is really not easy. So on a hot summer day, would you eat a bitter gourd?