Effectiveness of permethrin plus-C (Masterline®) and carbaryl (Sevin SL®) for protecting individual, high-value pines (Pinus) from bark beetle attack

Bark beetles (Coleoptera: Scolytidae) are commonly recognized as the most important mortality agent in western North American coniferous forests. High-value trees such as those located in residential, recreational, or administrative sites are particularly susceptible to attack. Regardless of landowner objectives, tree losses in these unique environments generally have a catastrophic impact. The value of these individual trees, the cost of removal, and the loss of aesthetics may justify protection until the main thrust of a bark beetle infestation subsides. This situation emphasizes the need for assuring that effective insecticides are available for individual tree protection. In this study, we assessed the efficacy of permethrin plus-C (Masterlineg®) and carbaryl (Sevin SL®) for protecting ponderosa, Pinus ponderosa Dougl. ex. Laws., lodgepole, P. contorta Dougl. ex Loud., and pinyon, P. edulis Engelm., pines from bark beetle attack during two field seasons. Masterline® was effective for protecting P. contorta from mountain pine beetle, Dendroctonus ponderosae Hopkins, attack for one field season. However, Sevin SL® was efficacious for two field seasons. An insufficient number of P. ponderosa and P. edulis control trees were killed to make definitive conclusions regarding efficacy in those systems. The data reported here regarding Masterline® is the first published report on its effectiveness for preventing bark beetle attack on standing trees. Masterline® appears to be an effective individual tree protection tool, but repeated applications will be necessary if multiyear control is desired.