Corn Red Spider Mite Control Methods and Effective Pesticide Recommendations
The corn red spider mite is one of the important outbreak pests in corn production. In different corn production areas, it occurs to varying degrees every year, especially after July in the north, when continuous high temperatures and drought will provide extremely favorable conditions for the occurrence of red spider mites. So what are the control methods for corn red spider mites? What pesticide is most effective?
Symptoms of corn red spider mite damage
The corn red spider mite spreads and causes damage by spinning silk and drifting with the wind, or by crawling, or by drifting and transferring with rainwater. It mainly gathers as adults and nymphs on the undersides of corn leaves to feed on sap, first feeding on the lower 3—5 leaves, then spreading to the upper leaves. The damaged areas show chlorotic spots or streaks, affecting photosynthesis. After the damaged leaves lose their green color and dry up, the mites move to other green leaves. Finally, the entire leaf turns rusty red and dies, appearing scorched.
Introduction to the corn red spider mite
The scientific name of the corn red spider mite is the corn leaf mite, mainly including three species: the truncated leaf mite, the two-spotted spider mite, and the carmine spider mite. In the north, leaf mites have 10-15 generations per year. Adult and nymph mites pierce and suck the tissue sap of corn leaves, first damaging the lower leaves, then gradually moving to the upper leaves. The damaged areas first show chlorotic spots, which gradually enlarge and fade from green to yellow. In severe cases, the leaves turn completely white and dry up, and later can cause shriveled and thin kernels, reduced grain weight, and yield loss, seriously affecting corn production.
Main reasons for the formation of corn red spider mites
1. Temperature and humidity
In July-August, when temperatures are relatively high and drought with little rain persists, the pest population will rise sharply and rapidly spread from spots to the entire field.
2. Short generation cycle
The corn red spider mite has strong reproductive capacity. It can reproduce 1 generation in 6—7 days, and can reproduce 10—20 generations per year, especially the high-temperature and drought weather appearing in July—August, which is suitable for its rapid spread and expansion.
3. Many hosts and large base population
In addition to damaging corn, the corn red spider mite also damages dozens of crops such as sorghum, cotton, soybean, cucumber, and potato. Dozens of weeds are hosts, including goosefoot (Chenopodium album) of the Chenopodiaceae family, amaranth of the Amaranthaceae family, wild soybean of the Fabaceae family, sour fruit of the Solanaceae family, and beggarticks of the Asteraceae family.
4. Farmers' weak awareness of control
Because the corn red spider mite is small and its damage is hidden, the public does not fully recognize its harmfulness and misses the optimal control period.
In addition, corn is a tall-stalk crop, and in recent years dense planting high-yield cultivation techniques have been widely promoted, thus bringing great difficulties to control work.
Control methods
1. Agricultural control: Clear weeds in fields, on field ridges, and beside ditches to reduce food sources and breeding sites for corn red spider mites; plant resistant (tolerant) varieties; avoid intercropping and relay cropping with soybean, etc.
2. Field spraying: Use 1.8% abamectin or 20% pyridaben emulsifiable concentrate at 2000 times dilution for spray control. Try to spray the pesticide solution on the undersides of corn leaves. For heavily infested fields, spray once every 10 days, continuously 2-3 times, all of which can achieve good results.
3. Smoke control: Where conditions permit, pyridaben emulsifiable concentrate or abamectin emulsifiable concentrate can be used, applying a smoke machine in the morning or evening when air pressure is low for control.
4. Row-cutting control: For denser corn fields, row-cutting control can be adopted, that is, cutting 2 rows to control 12 rows, using a motorized mist blower for motorized spray control.
5. Field fumigation: Use 3% phorate granules at 1.5 kg per mu, or mix 1 kg of 55% phorate emulsifiable concentrate with 20 kg of fine sand or sawdust, and evenly scatter it between corn rows for fumigation control.
Special attention should be paid to the following: because corn plants are tall and dense, the weather is hot, and ventilation conditions are poor, strictly follow pesticide use operation technical regulations, strictly prohibit the use of highly toxic pesticides and organizing mass large-scale pesticide application operations. After 10 a.m. and before 5 p.m., pesticide application is strictly prohibited to ensure the safety of people and livestock.