A Detailed Guide to the Latest Control Methods for Cotton Aphids
The cotton aphid is one of the major insect pests of cotton. Five species of aphids have been discovered: the cotton aphid, the cotton long-tube aphid, the alfalfa aphid, the hog plum aphid and the bean root aphid, among which the cotton aphid is the main one harming cotton and is one of the important pests of cotton in China, 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. Now let us take a look at the control methods for cotton aphids!
Symptoms of Cotton Aphid Damage
The cotton aphid produces 20 to 30 generations a year in the cotton regions of southern China and 10 to 20 generations a year in the cotton regions of northern China. In most parts 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 carries the honeydew excreted by the aphids, which often breeds mold. After being damaged, the plants become stunted, the leaves become smaller and fewer in number, 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, for example planting 372 and others.
2. Intercropping and relay intercropping can increase the species and numbers of natural enemies and control aphid damage, for example 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. Rotation between paddy fields and dry land 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 outside the cotton field. Where possible, apply chemical treatments 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 evenly with 1.5 to 2 kg of 3% carbofuran granules, or dress the seeds with aldicarb (also called Temik), using 50 grams 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 a seed coating agent, also gives very good results.
2. Spraying: dilute agents such as 50% monocrotophos, 50% phoxim, 40% omethoate, 40% biaoyading, 35% phosalone and 50% phosphamidon 1000 to 1500 times and spray.
3. Heart dripping: dilute 40% omethoate emulsion, 40% monocrotophos or 50% methamidophos emulsion 80 to 100 times, and use a sprayer to drip the solution onto the top of the cotton seedlings to control aphid damage.
4. Stem smearing: mix 40% omethoate emulsion or 40% monocrotophos or 50% methamidophos emulsion, polyvinyl alcohol and water in a ratio of 1:0.1:5 to make a stem-smearing agent, and use an implement similar to a writing brush to apply the solution to the purple-and-green alternating part of the cotton stem; the aphid control effect can reach more than 90%.