PEST CONTROL IN CONES AND SEEDS OF Pseudotsuga menziesii (Mirb.) Franco WITH SYSTEMIC INSECTICIDES

Abstract

Pseudotsuga species in Mexico are under special protection (NOM-059-SEMARNAT-2010). They face health issues due particularly to attacks by cone and seed-eating insects, which aggravate the low seed production and availability, which reflects in a limited natural regeneration of the species. This research aims to evaluate the effectiveness of three systemic insecticides for the control of pests of Pseudotsuga menziesii seeds and cones by determining the percentage of these damaged structures. The insecticides were evaluated using a randomized experimental design, with eight treatments and five replications of each, using a tree as an experimental unit. Treatments consisted on application of acephate (86.5, 173 and 259.5 mL L-1 of water), monocrotrophos (90, 180 and 270 mL L-1 of water) and thiamethoxam (25 g L-1 of water), and control units were included. Each tree received two 5 mL-applications per centimeter of DBH, at 25 cm from ground level, using the microinfusion system Arborjet Tree IVTM. Acephate and monocrotrophos at different concentrations showed statistically significant effectiveness, reducing insect attacks by over 85 %. Thiamethoxam did not show a favorable response. These results suggest that cone and seed-feeding insects of Pseudotusga menziesii can be effectively controlled by using tree injection system with the right dose of the suitable insecticide.