Delivery of chemical and microbial pesticides through drip irrigation systems

Abstract

Applying pesticides uniformly to the target area with drip irrigation systems is essential for achieving effectiveness of efficient insect or disease control and for the sustainability of a safe environment. The uniformity and recovery rate of water-soluble and insoluble materials of chemical and microbial pesticides with different physical properties discharged from emitters throughout driplines was evaluated. The materials were a water-soluble fluorescent tracer (BSF), a flowable water-dispersible insecticide (Imidacloprid), a suspendible microbial entomopathogenic fungus (EPF), a suspendible microbial soil fungicide (SF), and microbial entomopathogenic nematodes. Treatments also included three different flow capacities of emitters with nominally rated flow capacities of 1.9, 3.8, and 7.6 L h-1, respectively. Although all materials were readily deliverable through the drip irrigation system, the uniformity of the materials discharged varied with the material formulations and emitter flow capacity. For all emitter flow capacities, BSF had the lowest coefficient of variation, followed by nematodes, Imidacloprid, SF, and EPF. Conversely, the recovery rate of the five materials was in the reverse order. Emitter flow capacity affected the recovery rates of Imidacloprid and SF discharged from the emitters, but not of BSF, EPF and nematodes. Drip irrigation was demonstrated as a viable alternative for application of water-soluble and insoluble materials; however, the discharge rates of EPF and SF must first be determined to compensate for their non-uniformity of delivery and low recovery rates from emitters.