Best weather to spray corn (maize)

Corn (maize) is sprayed mostly early in the season for weeds, with fungicides and insecticides later as disease and pest pressure appear. The later applications are the challenging ones, because the crop becomes tall and dense.

The weather window

• Delta T: 2–8 °C. See Delta T.
• Humidity: avoid very dry afternoons, and wet foliage where the label advises against it. See humidity and dew point.
• Wind: a light, steady breeze within the label's range, measured at release height. See wind speed for spraying.
• Inversion: avoid calm dawn and dusk periods under an inversion. See thermal inversion.
• Rain: respect the product's rainfast period. See rain and spraying.

Crop-specific considerations

Early herbicide applications. Weeds are usually easiest to control small and actively growing. Early in the season, the soil is often exposed and the crop is short, so the boom sits close to bare ground: wind at boom height and drift toward neighbouring crops are the main concerns.

Tall crop, late season. Once corn is tall, ground application needs high-clearance equipment, and many operators turn to aircraft or spray drones. Release height is measured from the top of the canopy, not the ground, so a drone over tall corn is higher above the soil and more exposed to the wind at that level. Keep to the manufacturer's recommended height above the canopy and check the wind at the height you fly. See drone spraying weather.

Coverage in a tall canopy. Leaves higher in the plant intercept much of the spray. When the target is lower in the canopy, droplet class, water volume and a Delta T in range all matter.

Neighbours. Herbicides used in corn can injure susceptible crops and gardens nearby. Follow the label for buffers and wind direction.

Typical applications

Herbicides (pre- and post-emergence), fungicides, and insecticides against leaf and ear pests. Follow the label for rates, timing by growth stage and pre-harvest intervals.

Setting it up in PulveCast

Choose the Corn preset. It sets Delta T to 2–8 °C, humidity to 55–95 % and Medium as the ideal droplet class, and in automatic mode suggests a coarser class when the wind requires it. Crop presets are part of Pro; with the free Custom preset you can enter the same values. For drones, pick your drone model so the wind limit loads automatically.

Other crops

• Best weather to spray soybeans
• Best weather to spray sugarcane
• Best weather to spray cotton
• Best weather to spray wheat
• Best weather to spray coffee
• Best weather to spray rice
• Best weather to spray citrus
• Best weather to spray vineyards
• Best weather to spray potatoes
• Best weather to spray pastures