What Pests and Diseases Affect Bitter Gourd? A Detailed Guide to Prevention and Control

Bitter gourd, also known as bitter melon, is a plant in the Cucurbitaceae family and an annual climbing herb. The stems, branches, leaf stalks and flower stalks are covered with soft hairs, with tendrils growing from the leaf axils. The leaves reach 3 to 12 cm in diameter, with 5 to 7 palmate deep lobes; the lobes are elliptical with serrated outer edges. It flowers at the turn of spring and summer, is monoecious, and the flowers are yellow. The fruit is oblong-elliptical, with many irregular wart-like protrusions on the surface. The seeds are hidden within the fleshy fruit, and when mature are wrapped in a red aril. Bitter gourd is a vegetable that people love; its place of origin is unclear, but it is generally believed to be native to tropical regions. It is widely cultivated in South Asia, Southeast Asia, China, and the Caribbean islands.

Bitter gourd cultivation is mainly harmed by pests and diseases such as powdery mildew, downy mildew, Fusarium wilt, beet armyworm, tobacco cutworm and melon fruit fly. If not effectively controlled early, these will seriously affect the production efficiency of bitter gourd. So how should bitter gourd pests and diseases be controlled? The control methods are introduced below.

1. Powdery mildew

Cause and symptoms: Caused by a fungus, a species of cucurbit powdery mildew, it can infect many kinds of cucurbit plants. The recent alternation of high temperature and high humidity with high temperature and drought makes powdery mildew very prone to outbreaks. If prevention is neglected, taken lightly, or spraying is delayed, the melon leaves are often covered with white powder within a few days, the leaf color turns yellow, and growth weakens. Control methods: Besides paying attention to choosing disease-resistant varieties, spraying for powdery mildew must be timely. Generally, spraying should begin as soon as scattered small powder spots are found in the field, once every 5-6 days. You can choose 40% Miebingwei 700x solution, or 20% triadimefon wettable powder 800x solution, or 25% difenoconazole 1000x solution, or use Fenxiuxing or green copper. Spraying must reach both the upper and lower surfaces of the leaves, especially the lower surface. 2. Downy mildew

Cause and symptoms: The lesions are limited by the leaf veins and appear polygonal and light brown; in the later stage the lesions dry up and break easily, and in damp conditions a gray-black mold layer grows on the underside of the lesions. The disease gradually spreads from the lower part of the plant upward; in severe cases, the lesions join into patches, the whole leaf turns yellow-brown, dries and curls, and except for the new leaves at the top, most of the leaves on the whole plant die. The diseased field turns uniformly withered and yellow, the melons are thin and poor in quality, and the vines are pulled up early. Control methods:

1. Strengthen cultivation management, apply more organic fertilizer and phosphorus-potassium fertilizer to enhance the disease resistance of the plants.

2. At the early stage of the disease, use pesticides for control. You can choose the following agents: 53% Ridomil 600x solution, or metalaxyl-mancozeb 500x solution, or Sandofan 600x solution for spraying, or choose Kelu or Shuangtanqing. As for Fusarium wilt, in old bitter gourd production areas, especially the current high temperature and high humidity, it is favorable for the occurrence and spread of this disease. Choose 10% Shuangxiaoling aqueous solution 200x, or 30% DT fungicide 350x, or 50% carbendazim 300x for root drenching, 0.5 kg of solution per plant, once every 6 days, for 2-3 consecutive treatments.

3. Tobacco cutworm, beet armyworm

Recently the damage has been widespread, and larvae have been found boring into bitter gourds. They have the characteristics of being omnivorous, outbreak-prone and highly reproductive. The larvae cluster to cause damage in the young instars and disperse to feed in the older instars. Feeding activity begins to intensify rapidly at about nine in the early night, peaks at five in the morning, and basically stops by nine the next day. Control methods:

1. Trap and kill adults and larvae. Take the fermentation liquid of carrots, sweet potatoes and bean cakes, add a little sugar and trichlorfon to trap and kill adults; use fried peanut bran or soybean powder as bait, add about one liang of 90% trichlorfon to every 5 jin of bait, then mix in half a liang of Wanling powder. In the evening, put the poisoned bait in the field, placing a small pile of 2 tablespoons of poisoned bait about every one meter, and the larvae that crawl out to feed will be poisoned and die.

2. Strengthen field management, manually remove egg masses and capture clustered larvae, which can achieve twice the result with half the effort.

3. Chemical control. Use 1500x Yitaibao mixed with 2000x high-efficiency Miebaike, or abamectin mixed with high-efficiency Miebaike and then mixed with bt, or use 5 ml of Kung Fu mixed with 10 ml of Kulong in 15 kg of water for spraying. Choose evening for application; if it is rainy weather, spraying in the morning also works well. 4. Melon fruit fly

After hatching, the larvae bore into the melon to feed. The damaged melon first turns yellow in part, then the whole melon rots and deteriorates, with maggots wriggling inside, causing a large number of fallen melons. Even if it does not rot, the melon becomes deformed and sunken, and its quality declines. Control methods:

1. The most effective method is to trap and kill adults. Banana peels can be soaked in trichlorfon and hung under the melon trellis, or sweet potatoes can be cooked and fermented, then mixed with trichlorfon and a little essence and hung in containers inside the trellis. Put 20 points per mu, about half a liang at each point, to trap and kill adults.

2. Remove rotten melons and bury them deep or throw them into ponds.

3. When pest infestation is severe, use paper bags to cover the melons and protect them, preventing adults from stinging the melons to lay eggs.

4. Use pesticides at noon or in the evening to kill adults. You can choose the following agents: 40% Nongsite 2000x solution, or 4.5% Aruibao 1500x solution, or Lorsban, spraying once every 4 days, for 3-4 consecutive sprays.