The Latest Technical Method Tutorial for Eggplant Pest and Disease Control

Eggplant originated in India and was introduced to China in the 4th-5th century AD. The national eggplant cultivation area is about 3 million mu. The main diseases include eggplant phytophthora fruit rot, eggplant brown spot disease, damping-off, and rhizoctonia rot, and the main pests include red spider mites and American leafminers. Below let us take a look together at eggplant pest and disease control techniques!

Eggplant Phytophthora Fruit Rot

[Damage Symptoms] Eggplant phytophthora fruit rot is also called “rotten eggplant” and “dropped egg”. Besides damaging eggplant, it also damages tomato, cucumber, potato, etc. On eggplant, it mainly damages fruit, stems and leaves, and flowers can also be affected. On the fruit, initially water-soaked round or oval brown small spots appear, rapidly expand and become sunken, often the whole fruit rots, and in humid conditions white loose cottony mold grows; the internal flesh turns black and rots, and easily separates from the calyx. On young branches, water-soaked dark brown spots appear, constrict and wither and die; when seedlings are infected, damping-off symptoms occur.

[Disease Conditions] The pathogen mainly overwinters on diseased residues in the soil, and in the second year can directly infect the stems or roots of seedlings, or splash onto fruit near the ground through rainwater and cause fruit disease. The sporangia on the lesions undergo secondary infection through wind and rain and watering. Generally in July-August, with continuous rainy weather, stuffy hot weather, low-lying windless areas, poor drainage, and weak growth, the disease is severe.

[Control Methods] (1) Select disease-resistant varieties: such as Beijing Nine-Leaf Eggplant, Six-Leaf Eggplant, Tianjin Damang, Liaoqie No. 3, Fengyan No. 1, Jinan Early Small Long Eggplant, etc. (2) Agricultural control: never carry out continuous cropping with Solanaceous crops. Choose sandy loam soil with high dry terrain and good drainage, plant on high beds or small high ridges, or wide ridges with dense planting, apply sufficient base fertilizer, promptly remove diseased and old leaves and dispose of them centrally, do not use them for composting, harvest promptly after rain and promptly clean up diseased fruit. (3) Chemical control: spray once preventively before disease onset or before the rainy season; after disease onset, remove diseased fruit and diseased leaves, spray once about every 7 days, continuously 2-3 times. The chemicals include 1:1:160 Bordeaux mixture, 50% thiophanate-methyl 1000x solution, 50% captan 500x solution. At the peak of disease, spray 72% DuPont Curzate wettable powder 800-1000x solution, or 58% metalaxyl-mancozeb wettable powder 500x solution, 64% Sandofan wettable powder 500x solution.

Eggplant Brown Spot Disease (also called dry rot)

[Damage Symptoms] When seedlings are damaged, mostly near the ground at the stem base, approximately spindle-shaped water-soaked lesions form, later turning dark brown, sunken and shrunk. When conditions are suitable, the lesions expand and encircle the stem, and the seedlings damping off. When leaves are damaged, disease starts from the bottom leaves first and gradually develops upward, initially producing water-soaked brown spots, with grayish-white or light brown centers, and many small black dots arranged in a ring in the center. In dry conditions the lesions easily crack, and in rainy weather they easily form holes. When stems are damaged, the lesions are irregular in shape, sometimes water-soaked spindle-shaped lesions with dark brown edges and grayish-white centers, bearing many small black dots; the lesions gradually sink and dry-rot, and connect into longer necrotic areas. Fruit damage is the most severe; initially yellow-brown lesions appear on the fruit surface, slightly sunken, round or oval, expanding very quickly, and the fruit becomes semi-soft-rotten; later many small black dots are arranged in a ring, and finally the diseased fruit rots and drops off or shrivels on the branch into a mummified fruit.

[Disease Conditions] Eggplant brown spot disease is a fungal disease, and this fungus only infects eggplant. The pathogen overwinters on diseased residues on the soil surface and can also overwinter on seeds. Seed-borne bacteria are the main cause of damping-off and rhizoctonia rot in seedlings, and are also the route for long-distance spread of the pathogen. In the field, it mainly spreads through rain, insects, and field operations. The suitable temperature for disease onset is 28-30 degrees C, with relative humidity above 85%. In North China, July-August has high temperature and rain, or high temperature and high humidity, and the disease is severe. Excessive planting density also easily causes disease. In addition, continuous cropping, poor drainage, heavy clay soil, excessive nitrogen fertilizer, and late planting of early spring eggplant also lead to severe disease.

[Control Methods] (1) Seed treatment: soak seeds in 40% formalin 100x solution for 15 minutes, then take them out and wash clean with water; or soak seeds in mercuric chloride water 1000x solution for 10 minutes. (2) Agricultural control: carry out crop rotation with vegetables of other families for 2-3 years. Disinfect the seedbed; use Wudai mixture at 8-10 grams per sq m, or 50% carbendazim 10 grams, add 20 grams of fine soil and mix evenly; before sowing spread 1/3 on the bed surface, and after sowing cover with 2/3 medicinal soil. Strengthen cultivation management, that is, N, P, K fertilizers should be used in combination, apply sufficient base fertilizer, and promptly remove diseased plants, diseased leaves, and diseased fruit when found. (3) Chemical control: at the early stage of disease, use 75% chlorothalonil wettable powder 600x solution, 50% thiophanate-methyl 1000x solution, 65% zineb 500x solution, 70% mancozeb 500x solution. Spray once every 7-10 days, continuously 2-3 times.

Damping-off

[Damage Symptoms] Damping-off is also called “neck strangling”, and mainly infects at the seedling stage. After seeds germinate and before they emerge from the soil, disease can occur. Disease before emergence means rotten seeds or rotten sprouts. After emergence and before 2 true leaves, it mainly occurs at the stem base. The stem base of diseased seedlings near the ground shows water-soaked spots, then turns yellow and constricts into a line; when the cotyledons have not yet wilted, the seedling falls over on the ground, that is, when the seedling falls over, the leaves are still fresh green, hence the name damping-off. When the environment is humid, an obvious layer of white cottony mycelium grows on the diseased seedlings and the nearby soil surface.

[Disease Conditions] The pathogen overwinters in the soil with diseased plant residues, or lives saprophytically in humus. The pathogen can survive in soil for 2-3 years, and there are more pathogens in soil with high organic matter content. The pathogen spreads through rainwater or the flow of water in the soil. It reproduces relatively quickly at temperatures of 15-20 degrees C. Therefore, when raising seedlings in spring or winter, encountering rainy or snowy weather, or when the greenhouse has poor insulation, poor ventilation, and excessive watering, the seedbed temperature is often low and humidity high, and damping-off is severe.

[Control Methods] (1) Select disease-resistant varieties: according to local consumption habits and temperature conditions, select low-temperature-tolerant or early-maturing varieties, such as Jinan Small Long Eggplant, 94-1 Early Long Eggplant low-temperature-tolerant varieties, Liaoqie No. 1, Liaoqie No. 4 cold-tolerant varieties, etc. (2) Soil disinfection: 2-3 weeks before sowing, use 5 grams of thiophanate-methyl per sq m of seedbed mixed evenly with 50 times fine soil, and spread in the seedbed; or use 7-8 grams per sq m of a mixture of equal amounts of 65% zineb and 40% quintozene technical powder, or 8-10 grams of 50% carbendazim plus 15 kg of fine soil mixed evenly to make medicinal soil; before sowing first water thoroughly, and after the water seeps down, take 1/3 and spread on the bed surface, then cover the remaining 2/3 medicinal soil over the seeds, about 1 cm thick, so that the seeds are sandwiched in the middle of the medicinal soil. (3) Agricultural control: the seedbed should be chosen as fertile land with high dry terrain and good drainage. In the greenhouse, garden soil that has not grown Solanaceous fruit vegetables for many years should be selected as bed soil. Before sowing, strengthen ventilation and moisture removal in the seedling-raising site, and fully sun-expose the bed soil. After emergence, water as little as possible to increase ground temperature, and promptly ventilate and let light through. Cover the greenhouse with drip-free film to improve lighting conditions, so as to facilitate photosynthesis and improve seedling disease resistance. You can also spray 800x Lufeng 95 plant growth regulator to enhance seedling resistance.

[Chemical Control] After seedling disease occurs, use 75% chlorothalonil wettable powder 600x solution, 64% Sandofan M8 wettable powder 500x solution, 1000x Dexon solution, or 500x Thiram solution, or 800x carbendazim solution to spray the leaf surface. When disease occurs, use 800-1000x potassium permanganate solution to drench the roots, then wash the leaf surface.