Herbicides — kill the weed, spare the crop
Pre-emergence (residual) lays down a chemical barrier before weeds emerge; needs rainfall to activate. Post-emergence hits emerged weeds and is height-sensitive — labels cap weed height for a reason. Selective vs non-selective decides whether your crop survives. Drone note: post herbicides on tall weeds need coverage; don't starve the pass on carrier volume.
Fungicides — protect the factory
Mostly protectant (must be on the leaf before infection) or systemic/curative (limited kickback after infection). This is why timing beats everything: applied at VT–R1 corn or R3 soybean, you protect the leaves that fill grain. See the timing tool.
Insecticides — threshold, not reflex
Contact/stomach poisons (pyrethroids, organophosphates) versus systemics (neonics). Spray to a scouting threshold; insurance sprays flare secondary pests by killing beneficials and select for resistance. Pollinator language on the label is mandatory reading — see pollinator protection.
PGRs — change the plant's behavior
Plant growth regulators manage height/lodging (common in wheat and cotton) or fruit set. They are timing-critical to a growth stage and easy to get wrong — read the stage window twice, and know that stress conditions change the response.
What changes when a drone applies it
- Carrier volume is lower — check the label's minimum GPA.
- Coarser droplets cut drift but can hurt contact-product coverage — balance deliberately.
- Rotor downwash helps canopy penetration; height and speed consistency matter more than on a boom.
General extension guidance; the product label governs rate, timing, and legality. Next: modes of action & resistance.
Want it flown for you?
FactorDrones holds a commercial FAA Part 107 unmanned aircraft license; our pesticide applicator license (and FAA Part 137) are in progress. Reserve a price now and we’ll fly when fully cleared — or keep learning.