Control of Low-Level Nantucket Pine Tip Moth Populations: A Cost-Benefit Analysis

The Nantucket pine tip moth, Rhyacionia frustrana, an important pest of intensively managed loblolly pine, can cause significant long-term volume loss in plantations. The primary objective of this study was to establish an economic damage threshold beyond which chemical control of this pest becomes cost-effective. Tip moth damage estimates were obtained from 200 trees for each generation over a 3-year period after planting on two sites in the Georgia Piedmont. A volume index (DH) was obtained for each of these trees at the end of the study. Significant reductions in volume were observed among trees with relatively low damage levels (10–30% of shoots infested on average over a 3-year period) compared with those trees sprayed with insecticide throughout the study. Growth projection models were used to extrapolate 3-year volume differences among treatments to a full rotation. These and other parameters were used to calculate land expectation values and, subsequently, willingness to pay values for tip moth control at the beginning of the rotation using various discount rates. The results of this analysis suggest that an economic injury level for R. frustrana may be reached when damage levels, on average, exceed 30% infested shoots. South. J. Appl. For. 30(4):182–187.