Basic Test Information
1. Test Crop: Field-transplanted young watermelon seedlings
2. Target Pest: Cotton aphid (Aphis gossypii)
3. Test Location: Watermelon Planting Base, Zhengzhou, Henan Province
4. Test Period: March 2026
5. Test Pesticide: 70% Imidacloprid Water Dispersible Granules (WDG)
6. Reference Pesticide: Mainstream commercial aphicide products of the same category on the market
7. Test Conditions: The field experienced sustained high temperature and drought, triggering an outbreak of cotton aphids at the watermelon seedling stage. Massive black nymphs and adult aphids densely covered the undersides of leaves. Sucking damage by aphids caused leaf chlorosis, crinkling, and sticky honeydew coating leaf trichomes. Leaf margins of some seedlings turned dry and scorched, with an extremely high pest population base.
Visual Field Performance
1. Blank Control Group:
Aphids continued to reproduce after pesticide application. Seven days later, leaves were fully covered with honeydew and mold. Watermelon leaves suffered severe crinkling and yellowing, and seedling growth was arrested. Aphids spread massively to newly emerged tender leaves, with damage worsening continuously.
2. Treatment Group with 70% Imidacloprid WDG
• 24 hours after application: The vast majority of aphids on leaf undersides became poisoned, stiffened, turned black and fell off. Only a tiny number of old instar nymphs survived, and honeydew secretion on leaves ceased completely.
• 3 days after application: Hardly any live aphids remained on tagged leaves. Damaged leaves stopped curling, and newly grown tender leaves stayed clean and pest-free.
• 7 days after application: No aphid resurgence was observed. Leaves stretched out and remained emerald green, free of honeydew and sooty mold. The product was safe to young watermelon seedlings with no phytotoxic symptoms such as chemical spots or yellowed leaves, and its persistent efficacy far outperformed the reference pesticide.
V. Test Conclusions
1. For explosive cotton aphid infestations on watermelon seedlings, our product delivers outstanding quick knockdown performance. It rapidly suppresses pest populations within 1 day after spraying, and achieves peak control efficacy on the 3rd day.
2. The product features an ultra-long residual effect. It maintains a stable control efficacy of over 95% even 7 days post-application, helping farmers reduce spraying frequency and cut labor & pesticide costs.
3. The pesticide boasts excellent adhesion on leaf surfaces and strong penetration through the hairy foliage of watermelon. It can penetrate dense trichomes to contact-kill aphids hiding on leaf undersides, showing remarkable lethal activity against both mature adults and nymphs of all instars.
4. It exhibits high crop safety on watermelon with zero phytotoxicity when applied at the seedling stage. It also prevents sooty mold induced by aphid honeydew and supports normal vegetative growth of watermelon. Farmers who visited the demonstration field gave highly positive feedback, making the product highly valuable for market promotion.
