Measurement of spray deposition and efficiency of pesticide application in citrus orchards

Abstract

Pesticide treatments on citrus, in Spain, are performed manually and with application rates varying from 3000 to 9000 l/ha. This work was carried out to find methods of mechanizing these operations as an alternative to the conventional methods, with the purpose of achieving equal efficiency, but at a lower cost. Spray penetration, droplet size, run-off, and pest control were determined for four types of equipment (hand lances, oscillating nozzles, air-assisted, and low pressure air-assisted sprayers). The experiment was conducted in a Salustiana orange orchard on a randomized block with three replications. With all the machines, pentration varied between the outside and the inside parts of the tree, especially for the two air-assisted systems. The oscillating nozzles method provided a very similar performance to that of the hand lances, and therefore, it could be used as a replacement or alternative method, with a considerable saving of production costs. Good pest control was achieved for aphids with all the equipment tested, and in this case, any of the two air-assisted methods could be used. For Lepidosaphes sp. there appeared to be better control of the pests in the outer zones than in the inner parts of the tree, and none of the methods used solved this problem completely.