COMPARISON OF SPRAY INSECTICIDES AGAINST CITRUS LEAFMINER

ABSTRACT

A field experiment was conducted on ‘Tangor Murcott’ spring flushes during 1999 to control citrus leafminer (CLM) Phyllocnistis citrella (Lepidoptera: Gracillariidae) in Cordeirópolis County, State of São Paulo, Brazil. Insecticides and respectively concentrations (g AI/100 liters of water) used were thiamethoxam 250 WG (3.0; 4.0 and 5.0), thiamethoxam (4.0) + petroleum oil (PO) 80EC (200.0), abamectin 18EC (0.54) + PO (200.0), lufenuron 50EC (3.75) + PO (200.0), pyridaphention 400EC (30.0), pyridaphention (30.0) + PO (200.0) and PO (200.0 and 800.0). Two foliar sprays were made at interval of ten days. Three days after the 1st application, abamectin + PO and lufenuron + PO, both considered as standards, provide significantly greater CLM larval mortality, with 86.8% and 93.3% of larval density reduction, respectively. During the same date, only lufenuron + PO showed good control of larvae + pupae (86.2%). For all insecticide treatments, with the exception of thiamethoxam at 3.0g and 4.0g, the number of larvae per flush was lower than for untreated control at 7 days after the 1st application, ranging from 57.4% (PO - 200.0g) to 98.9% of reduction (abamectin + PO). In this evaluation, abamectin + PO caused the highest reduction (87.2%), thiamethoxam (5.0) provided good control (74.0%) while pyridaphention treatments were not significantly different from the check, based on the number of CLM larvae + pupae. Five days after the 2nd application, only abamectin + PO provided significant reduction in larval (93.9%) and larval + pupal (95.0%) densities. In the same date, lufenuron + PO showed significantly lower larval + pupal density per flush (75.4% of reduction). Although thiamethoxam + PO has been inferior to standard insecticides 5 days after the 2nd application, it caused a 63% of CLM larval reduction. Eleven days after the 2nd application no significant differences in larval or larval + pupal infestation were detected among treatments. The results suggest that studies with thiamethoxam to control P. citrella should be developed at 2.0 g AI/100 liter of water or higher doses with the addition of PO.

KEY WORDS: Insecta; pest; citrus; Phyllocnistis citrella, chemical control.