Recycling Tunnel Sprayer for Pesticide Dose Adjustment to the Crop Environment

The article presents the results of field trials of an air-assisted tunnel sprayer with recycling of the liquid not captured by the foliage. The influence of leaf density and spray flow rate on plant and ground deposits was studied. The trials were repeated on a spur-pruned, cordon-trained vineyard spraying the same flow rate at three growth stages; three flow rates were then compared in the last stage test. Liquid losses to the ground were less than 2% of that sprayed in every combination of vine growth stage and spray flow rate. When operating beneath the dripping limit, canopy density and flow rate did not affect losses, which totaled about 8% of the liquid sprayed. These results could be used in real treatments to calculate the amount of liquid retained by the plants simply by measuring the amount of spray recycled by the machine along a known path. This would allow a highly precise distribution of the required dose in a single spraying at a specific growth stage. As in previous trials, the recycling tunnel sprayer showed high environmental sustainability compared to traditional machines.