Growth Impact of Pine Tip Moth on Loblolly Pine Plantations in the Ouachita Mountains of Arkansas

Abstract

Abstract Growth impact of pine tip moths (Rhyacionia spp.) in two 12-year-old Arkansas loblolly pine (Pinus taeda L.) plantations was measured, and growth loss through rotation was projected. Two tip moth control treatments (azinphos-methyl foliar spray and carbofuran granules) were appliedto trees in the protected treatments at ages 3, 4, and 5, and growth was compared to unprotected trees at 2-year intervals. Trees in protected treatments had significantly greater average height (2.0 ft), dbh (0.35 in.), and total volume (182 ft³/ac) than did trees in the unprotectedtreatment. Volume losses at age 12 were proportional to tip moth infestation levels during the period of protection. Potential long-term impact of a tip moth was estimated using the results of this study as input to growth and yield models for thinned and unthinned stands. Projected gainsfrom early tip moth control in light to moderately infested stands were: unthinned, 2 to 6 cords/ac at age 30; thinned, 300 to 700 bf/ac of sawtimber and 1 to 3 cords/ac of pulpwood on a 35-year rotation. An economic analysis comparing the present value of growth benefits to the treatmentcosts showed tip moth control to be marginally cost effective only in the thinned, sawtimber regime. South J. Appl. For. 11(2):128-133