Detailed Explanation of the Damage Symptoms and Control Methods of Cotton Aphids

Growing Techniques Jan 1, 1970 0 views

The cotton aphid is one of the major insect pests of cotton. Five aphid species have been identified: the cotton aphid, the cotton long-tube aphid, the alfalfa aphid, the turnjujube aphid, and the bean root aphid. Among them, the cotton aphid is the main one damaging cotton and is one of the important pests of cotton in our country, causing the most severe damage in the cotton regions of the Yellow River basin and the Liao River basin, followed by the cotton region of the Yangtze River basin.

Damage Symptoms of Cotton Aphids

The cotton aphid produces 20 to 30 generations per year in the southern cotton region of our country and 10 to 20 generations per year in the northern cotton region. In most areas of the country, the eggs overwinter on the four major overwintering hosts: hibiscus, pomegranate, Sichuan pepper, and holly. It inserts its piercing-sucking mouthparts into the underside of cotton leaves or the tender growing tips and sucks the sap. The damaged leaves curl toward the underside, and the leaf surface bears the honeydew excreted by the aphids, which often breeds mold. After being damaged, the plants become stunted, the leaves become smaller, the number of leaves decreases, and squaring is delayed with fewer squares and bolls.

Agricultural Control of Cotton Aphids

1. Planting insect-resistant varieties is an effective measure for controlling cotton aphids, such as planting 372 and others.

2. Intercropping and relay intercropping can increase the variety and number of natural enemies and control aphid damage, such as intercropping cotton with wheat, intercropping cotton with mung bean, green manure, and others, and planting trap crops such as corn, rapeseed, and sorghum in between.

3. Paddy-upland rotation can reduce the occurrence of cotton aphids. Where conditions permit, rotate cotton with rice.

4. Deal with the overwintering hosts to reduce aphid sources in early spring. Generally, before the cotton seedlings emerge, clear the weeds inside and around the cotton field. Where possible, apply chemical treatment to the four major cotton aphid overwintering hosts: Sichuan pepper, pomegranate, hibiscus, and holly, which can reduce the aphid population in the cotton field.

Chemical Control of Cotton Aphids

1. Seed dressing: Before sowing cotton, mix the seed amount per mu with 1.5 to 2 kg of 3% carbofuran granules and blend evenly, or dress the seeds with aldicarb (also called temik), using 50 g of active ingredient per mu, which can control aphid damage for 40 to 50 days. Dressing seeds with 3911 (phorate) emulsion or granules, or with seed coating agents, also gives very good results.

2. Spraying: Spray with agents such as 50% monocrotophos, 50% phoxim, 40% omethoate, 40% bifenthrin, 35% phosalone, and 50% phosphamidon diluted 1000 to 1500 times.

3. Dropping onto the growing point: Dilute 40% omethoate emulsion, or 40% monocrotophos, or 50% methamidophos emulsion 80 to 100 times, and use a sprayer to drop the solution onto the top of the cotton seedlings to control aphid damage.

4. Stem smearing: Use 40% omethoate emulsion, or 40% monocrotophos, or 50% methamidophos emulsion, polyvinyl alcohol, and water in a ratio of 1:0.1:5 to prepare a stem-smearing agent. With an implement similar to a writing brush, smear the solution onto the purple-and-green alternating part of the cotton stem. The aphid control effect can reach more than 90%.

Agricultural Control Methods for Cotton Verticillium Wilt

The agricultural control methods for cotton Verticillium wilt mainly consist of a series of management measures from cotton seed selection, sowing, growth, and harvest to post-harvest. The following is a detailed introduction for everyone.

Agricultural control methods:

(1) Before sowing and after harvest, clear the weeds and diseased crop residues in and around the field, and burn them in a centralized manner or compost them; deeply plow the land and destroy the stubble to promote the decomposition of diseased residues and reduce pathogens and pest sources.

(2) Rotate with non-grass-family crops; paddy-upland rotation is best.

(3) Choose fields with convenient irrigation and drainage, dig drainage ditches well, lower the groundwater level, and achieve no standing water after rain stops; after heavy rain, clear the ditch system in time to prevent moisture retention and lower field humidity. This is an important measure for disease prevention.

(4) For fields with many soil pathogens or severe underground pests, broadcast or furrow-apply sterilizing and insecticidal medicated soil before sowing or transplanting.

(5) Choose disease-resistant varieties and use disease-free, coated seeds. If not coated, the seeds must be sterilized with a seed dressing agent or seed soaking agent.

(6) For seedling raising and transplanting, cover the seeds with medicated soil after sowing, and spray an insecticidal and sterilizing agent once before transplanting. This is the key to disease prevention.

(7) For direct sowing in the field, sow early at the proper time, thin the seedlings early, cultivate the soil early, and fertilize early, and cultivate and earth up in time to grow strong seedlings; spray a mixed insecticidal and sterilizing agent once before the seedlings close the rows.

(8) Apply compost fermented with effective microorganisms or thoroughly decomposed organic fertilizer. Do not use pathogen-carrying fertilizer, and the organic fertilizer applied must not contain diseased plant residues. Adopt soil testing and formula fertilization technology, appropriately increase the application of phosphorus and potassium fertilizers, strengthen field management, and grow strong seedlings. After typhoons and heavy rain, topdress in time to enhance the disease resistance of the plants, which helps reduce the disease.

(9) Control pests in time to reduce plant wounds and reduce the transmission routes of pathogens; when the disease occurs, promptly remove diseased leaves and diseased plants and carry them out of the field to burn, and apply medicine or quicklime to the diseased holes.

(10) Plant at a reasonable density, prune in time, promptly remove the lowest 2 to 3 leaves on the stem, promptly cut empty branches, remove old leaves, and pull out diseased plants and burn them in a centralized manner, apply medicine to the diseased holes, and increase ventilation and light penetration in the field.

(11) During high temperature and drought, irrigate scientifically to increase field humidity and reduce the damage and virus transmission by aphids and small brown planthoppers. Continuous irrigation and flood irrigation are strictly prohibited.

(12) Protect disease-free areas. Do good quarantine work and strictly prevent the expansion of diseased areas.

(13) Select and breed disease-resistant varieties.

Agricultural Control Methods for Cotton Mosaic Virus Disease

For the agricultural control of cotton mosaic virus disease, at the beginning choose disease-resistant varieties, plant at a reasonable density, appropriately increase the spacing, and pay attention to the amount of fertilizer applied.

Agricultural control of cotton mosaic virus disease:

(1) Before sowing or after harvest, clear the weeds, dodder, and diseased crop residues in and around the field, and burn them in a centralized manner or compost them; deeply plow the land and destroy the stubble to promote the decomposition of diseased residues and reduce pathogens and pest sources.