Yeah, aircraft. I am pretty sure that's how they did us with agent orange.
That was nasty stuff, mostly due to TCDD, a chemical artifact and contaminant in the manufacturing process for Agent Orange and similar defoliants. The Vietnamese government is still angling for compensation for environmental damage and a high rate of birth defects and developmental abnormalities where it was most intensely sprayed. Of course, many of those problems are due not to chemical residues but to poor villagers subsisting on primitive rice cultivation and with high exposure to pathogens and natural toxins.