Trunk-Implanted Systemic Insecticides for Slash Pine Cone Insect Control

P. Merkel Edward


Four systemic insecticides, dimethoate, oxydemetonmethyl, dicrotophos, and Monitor (O, S-dimethyl phosphoramidithioate), were implanted into trunks of 40-foot slash pines, Pinus elliottii Engelm. var. elliottii, to control coneworms (Lepidoptera: Phycitidae: Dioryctria spp.) and the slash pine seedworm (Lepidoptera: Olethreutidae: Laspeyresia anaranjada Miller) in maturing cones. All insecticides, when implanted in drilled holes on 8 May 1968 at a dosage of 5 g active toxicant per diameter inch, reduced Dioryctria cone infestation by 80-89% during the last 4-1/2 months of cone development. Dicrotophos and oxydemetonmethyl at the 5 g/inch dosage also reduced cone infestation by the slash pine seedworm by 97% and 95%, respectively. Monitor and oxydemetonmethyl at a 2 g/inch dosage rate failed to control either the coneworms or the seedworm. No phytotoxicity was observed in any of the treatments.

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