Analysis of the southern pine beetle suppression program on the national forests in Texas in the 1990s

Abstract

Infestations of the southern pine beetle (SPB) (Dendroctonus frontalis Zimmermann) affected 7,929 ac of managed forest and 13,346 ac of wilderness on the National Forests in Texas (NFT) during the 1990s. Direct control treatments were applied to two-thirds of the 8,486 infestations on managed forest; the average size of treated spots was 1.3 ac. Inactive infestations averaged only 0.25 ac. Cut-and-remove was the preferred treatment; and only one application per infestation was required for over 97% of infestations treated by this method. Cut-and-leave was applied to 27% of infestations requiring treatment; and a single application was effective for 90% of treated infestations. In wilderness, where SPB suppression was limited due to legal constraints, large infestations developed, killing over 40% of the susceptible host type. In contrast, less than 2% of the susceptible host type was killed in nonwilderness areas of the NFT. Economic analyses indicate the SPB suppression program was cost-effective, with an estimated benefit/cost ratio of 3.55:1.