Best weather to spray pastures
The weather window for spraying pastures and grassland — Delta T, humidity, wind, inversion and rain — plus grazing, clover, hills and Custom settings.
Pasture spraying is mostly weed and brush control, often with herbicides that also affect broadleaf plants outside the field. Pastures are frequently next to gardens, shelter belts, water and other crops, and are often on rolling or hilly ground, so drift control and site conditions matter as much as the weather.
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, blowing away from sensitive areas. See wind speed for spraying.
- Inversion: hollows and valleys hold cold air on calm, clear nights. See thermal inversion.
- Rain: leave the rainfast period clear, and avoid spraying before heavy rain near water. See rain and spraying.
- Temperature: weeds should be actively growing. See temperature and spraying.
Crop-specific considerations
Actively growing weeds. Systemic herbicides generally work best on weeds that are growing well, not stressed by drought, heat or cold. The label may specify the weed growth stage.
Grazing and livestock. Labels set grazing and harvest withholding periods, and sometimes restrictions for particular livestock. Plan stock movements around them.
Clover and desirable species. Some herbicides damage clover and other legumes in the sward. Check the label for effects on the pasture itself.
Hills and spot spraying. On steep or broken ground, where ground equipment struggles, spray drones are used in some countries for spot and patch treatments. Wind on hills is channelled and gusty, so check it on site. See drone spraying weather and agricultural drone rules by country.
Water. Pastures often include streams, dams and wet areas. Respect label buffers and avoid drift and runoff into water.
Typical applications
Herbicides for broadleaf weeds and brush, spot treatments, and in some systems pasture renovation before resowing.
Setting it up in PulveCast
There is no pasture preset, so use Custom. It starts from Delta T 2–8 °C, humidity 55–95 % and a Medium droplet class. Conservative starting points:
- Keep Delta T at 2–8 °C.
- Set the droplet class to what your nozzles or drone produce, or leave it on automatic; coarser classes help near sensitive areas.
- Lower the maximum wind from the 25 km/h default towards 15 km/h (about 9 mph), or to the label's limit. For drones, pick your drone model.
- Keep the thermal inversion threshold at the 1.5 °C default.
Other crops
- Best weather to spray soybeans
- Best weather to spray corn (maize)
- 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
Frequently asked questions
When should I spray pasture weeds?
When weeds are actively growing and at the stage the label recommends, in a window with a light, steady wind blowing away from sensitive areas, no inversion, Delta T in range and no rain within the rainfast period.
How long before livestock can graze after spraying?
It depends on the product. The label sets the grazing withholding period and any livestock-specific restrictions. Follow it exactly.