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Cotton bollworm control tricks
1. Pruning: According to field surveys, timely pruning during the second generation of bollworm significantly reduces egg numbers by 40–60%. In fields affected by the second-generation cotton bollworm, the number of eggs and larvae dropped by 3.8–54.5%, with an average reduction of 27.7%. During the peak of the fourth generation, removing side shoots and axillary buds in a timely manner reduced the population of eggs and larvae by 52.5% and 58%, respectively. This method is particularly effective in managing infestations before they escalate.
2. Egg Removal: Approximately 80% of the second-generation *Helicoverpa armigera* eggs are laid on tender tips and the front of leaves. At the peak of egg-laying, wiping off the eggs using a cloth or similar tool at regular intervals—once every three days for 3–4 times—can effectively reduce the damage caused by these pests. Surveys show that even two rounds of wiping can decrease egg counts by 60% or more, with some cases reporting up to 80–90% reduction in egg numbers.
3. Irrigation: During the flood season of *Helicoverpa armigera*, combining irrigation with flooding can increase mortality rates in alfalfa fields by around 70%. Another study found that if the soil surface is flooded for about 1.5 hours, the mortality rate of cotton bollworms reaches 100% within one day after the water recedes. The death rate remains high for 3–4 days, reaching 77–85% and 61–73%, respectively. This technique is especially useful in areas where water management is feasible.
4. Foliar Fertilizer Spraying: During the adult stage of the cotton bollworm, applying a foliar spray made from 1–2% superphosphate solution can reduce egg laying by 33.3–74.4% in cotton fields, with an average reduction of 55%. This method not only helps control the pest population but also provides nutritional benefits to the plants.
5. Cockroach Control: After wheat harvest, killing the larvae promptly can achieve a bollworm kill rate of up to 44.4%. This practice is crucial in preventing the larvae from moving to other crops and causing further damage.
6. Timing of Spraying: Bollworms are sensitive to light and tend to be active at night. Using insecticides such as Bt (Bacillus thuringiensis), phoxim, or formulations containing phoxim, which have light-repelling properties, and spraying them in the early morning or late evening can improve their effectiveness by about 20%. This timing ensures better contact between the pesticide and the pest.
7. Comprehensive Spraying: When bollworms are present, applying the same pesticide in a thorough and extensive manner, rather than spot spraying, increases the control effect by 30–40%. This approach ensures that all potential hiding spots and infested areas are treated, leading to more effective pest management.
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