crop dusters don't leave chemtrails (by the commonly used definition)they leave a cloud of poison behind them, typically from about a ten foot altitude. I've seen those crazy pilots go UNDER highline wires. The chemicals are only in the air a few seconds. They typically do NOT spray on windy days. (why waste expensive chemicals on nontargeted plants?)
Everyone knows that. Farmers pay big bux to have the poison sprayed on their crops. It's either that or lose the crops to bugs. If that happens often enough everyone starves.