Key Technical Points of 'One Spray, Multiple Promotes' for Autumn Crops

Currently, in the main production areas, corn is entering the flowering and milk-ripe stages, medium rice is in the heading and panicle emergence stages, and soybeans are approaching the flowering and pod-setting stages. These are critical periods for yield formation and the ‘One Spray, Multiple Promotes’ window. However, challenges such as floods, high temperatures, droughts, cold damage, and pest threats still exist. In the mid-to-late growth stages of autumn crops, spraying a mixture of foliar fertilizers, growth regulators, stress resistors, insecticides, and fungicides can achieve multiple effects, including promoting growth, enhancing grain filling and maturation, aiding post-disaster recovery, and increasing yield. This is a key strategy for preventing disasters and increasing production during these stages. By adhering to the principle of “tailored strategies, optimized fertilizers and pesticides, precise spraying, and ensuring safety,” the implementation of ‘One Spray, Multiple Promotes’ will help solidify the foundation for abundant harvests of autumn crops.

(1) Tailored Strategies Based on Local Conditions

In Northeast China, spring corn is in the flowering and milk-ripe stages, spring soybeans are in the flowering and pod-setting stages, and medium rice is in the heading and panicle emergence stages. Focus should be placed on threats from waterlogging, low-temperature cold damage, and early frost, as well as pests such as corn borer, southern corn rootworm, soybean rust, and various rice pests like rice blast, sheath blight, rice planthopper, etc. In the Huang-Huai-Hai region, summer corn is approaching the tasseling and flowering stages, and summer soybeans are entering the flowering and pod-setting stages. Here, the focus should be on northern waterlogging and southern high temperatures, as well as pests such as southern corn rust, corn earworm, and others like soybean downy mildew, pod borer, etc. In the middle and lower reaches of the Yangtze River, medium rice is at the heading and panicle emergence stages, where attention should be given to high temperatures, drought, floods, and cold dew winds, along with pests like rice blast, sheath blight, and rice stem borers. In the Northwest, spring corn is in the tasseling and flowering stages, spring soybeans are in the pod-setting and grain filling stages, and summer soybeans are in the flowering and pod-setting stages. Focus should be placed on droughts and early frosts, as well as pests such as southern corn rootworm, soybean weevil, and others. The ‘One Spray, Multiple Promotes’ strategy should be adapted to local conditions, growth stages, pests, and disasters to ensure optimal results.

(2) Optimizing Fertilizers and Pesticides, Scientific Formulation

To cope with natural disasters, regions experiencing high temperatures and drought should spray potassium dihydrogen phosphate, micro-element water-soluble fertilizers, and drought-resistant agents. For waterlogged fields, after draining, foliar spraying of urea and potassium dihydrogen phosphate is recommended. In areas threatened by early frost, phosphorus-potassium fertilizers or liquid films can be sprayed. Corn growth regulators may include substances like 30-hydroxy, tebuconazole, brassinolide, and indole-3-butyric acid. For soybeans, the main growth regulators are also 30-hydroxy, brassinolide, and indole-3-butyric acid. For pest and disease control, corn fungicides include azoxystrobin, tebuconazole, and other combinations like azoxystrobin + propiconazole, while insecticides include chlorantraniliprole, emamectin benzoate, and other options. For soybeans, fungicides include azoxystrobin, pyraclostrobin, and others, while insecticides are similar to those used for corn. For rice, fungicides include triadimefon, azoxystrobin microcapsule suspension agents, and more. Insecticides for rice may include imidacloprid, chlorantraniliprole, and others.

(3) Timely Spraying, Precise Dosage

Spraying should be done when wind speeds are below level 3 and temperatures do not exceed 30°C. Generally, spraying is done in the morning before 9:00 AM or in the late afternoon after 4:00 PM, avoiding the midday heat. If moderate to heavy rain occurs within 24 hours after spraying, reapply promptly. Drones can be used for nighttime operations depending on local conditions. When using drones, the application rate should be at least 1.5 liters per acre, with appropriate spray additives in the liquid to improve droplet retention, reduce drift, and enhance evaporation resistance. When using high-clearance sprayers or vehicle-mounted sprayers, the liquid volume per acre should exceed 30 liters.

(4) Unified Operations, Ensuring Safety

Prior to spraying, public announcements should be made in accordance with relevant regulations, and warning signs should be set up to prevent poisoning and accidents. Drones should be the preferred method for unified spraying, with a flight speed controlled between 3–5 meters per second. The flight altitude should be adjusted based on the drone’s load capacity: drones with a load of 30 liters or less should fly 2–3 meters above the crop canopy, and those with a load greater than 30 liters should fly 3.5–4.5 meters above the crop canopy, to prevent stem breakage during operation. Drones should avoid obstacles and personnel during take-off and landing, and operators must wear necessary protective equipment and avoid areas downwind of the spray. Smoking and eating are prohibited during operation. For fields not suitable for drone operation, high-clearance sprayers or vehicle-mounted sprayers should be used as needed. Before large-scale spraying, small-scale trials should be conducted to assess potential risks and prevent damage to non-target organisms or neighboring crops due to spray drift.