Use this field scouting template to check if pest or weed damage has crossed the economic threshold. Get exact knapsack mixing rates, safety waiting periods, and weather timing advice.
Never spray blind! Check whether pest numbers actually justify buying and spraying chemicals, or if waiting will save you money.
Spraying chemicals when only 2% of plants have bugs wastes your money and kills beneficial predator insects (like ladybirds). But waiting too long allows caterpillars to bore into stems where sprays cannot reach them. This tool calculates the exact Economic Damage Threshold for your field.
Master the principles of Integrated Pest Management (IPM), knapsack calibration, and toxicity color bands to protect your wallet and your health.
Never judge a whole 5-hectare field by looking only at the plants next to the road. Walk across your field in a large W-shaped pattern. Stop at 5 evenly spaced spots. At each stop, inspect 10 consecutive plants closely (look inside funnels, under leaves, and at the ground). Write down the number of infested plants. Total infested divided by 50 gives your exact infestation percentage.
Using the wrong water volume causes overdosing (scorching crops) or underdosing (weeds survive). To calibrate: Measure a 10m x 10m plot (100m²). Fill knapsack with clean water to a known mark. Spray the 100m² plot at your normal walking speed. Measure how many litres of water you used. Multiply by 100 to get litres needed per hectare!
Every legitimate chemical bottle has a colored band across the bottom:
🟢 Green Band (Caution): Low mammalian toxicity; safest for humans and beneficials.
🔵 Blue Band (Warning): Moderately hazardous; wear gloves and mask.
🟡 Yellow Band (Danger - Poison): Highly toxic; handle with extreme caution.
🔴 Red Band (Very Toxic - Restricted): Lethal poison; restricted to certified operators only.
Pre-emergence herbicides (e.g. Atrazine) form a chemical seal on the soil surface that kills weed seedlings as they germinate. They MUST be sprayed onto moist soil within 48 hours of planting. Post-emergence herbicides (e.g. Nicosulfuron, Fluazifop) are sprayed onto growing green weed leaves and absorb through the foliage.
Caterpillar sprays fail for three main reasons: 1. Spraying too late: Large caterpillars (> 2cm) are tough and hide deep inside cobs. 2. Wrong nozzle / aim: Spray was broadcast over the leaves instead of directed into the plant funnel. 3. Chemical resistance: Using the same cheap synthetic pyrethroid spray (e.g. Cypermethrin) 5 times in a row. Always rotate chemical active ingredients (e.g. switch to Emamectin benzoate or Chlorantraniliprole).
Yes! Selective graminicides (like Fluazifop-P-butyl or Quizalofop) kill only true grasses (annual grass, couch grass) and will not harm broadleaf plants like tomatoes, cabbages, beans, or potatoes at all. However, NEVER spray selective grass killers on maize, wheat, or sorghum, as they will kill your cereal crop!
Most contact pesticides and herbicides need at least 3 to 4 rain-free hours ("rainfastness period") to absorb into plant tissue. If heavy rain fell within 1 hour, up to 70% of the active chemical washed off onto the ground. Wait 48 hours, re-scout your field to check if pests survived, and re-apply if necessary.