Timing is free. It costs nothing to spray at six in the morning instead of midday, and yet the difference in result can be substantial. Three things drive this: heat, wind and the plant itself.

Heat is the first problem. Spraying in the middle of a hot day means a good share of your droplets evaporate before they reach the leaf, and what does land dries too fast to be absorbed properly. Systemic products in particular need time on the leaf surface to move into the plant. Early morning and late afternoon give you that time.

Wind is the second. A breeze that feels pleasant while you work is often enough to carry fine droplets off your target and onto a neighbouring crop. Drift wastes the product you paid for and can damage someone else's field. Calm conditions are worth waiting for.

The plant matters too. Many insects feed in the cooler parts of the day, and weeds actively growing in the morning take up systemic herbicide more readily than weeds that are heat-stressed at noon. You are aiming at a moving target, so spray when the target is active.

Rain is the last consideration. Check the rainfast period on the label — the time the product needs on the leaf before rain can wash it off. Spraying an hour ahead of a downpour is simply pouring money on the ground.

None of this requires new equipment or a better product. It only requires spraying at the right time, and that is a decision you make for free.