Kurt K. Allen

Testing Verbenone for reducing mountain pine beetle attacks in ponderosa pine in the Black Hills, South Dakota

In 2000 and 2002, Verbenone, a compound with anti-aggregation properties for mountain pine beetle, Dendroctonus ponderosae, was tested for reducing attacks by the insect in Ponderosa pine, Pinus ponderosae forests. The verbenone was released to the environment with the use of permeable membranes; the first year with plastic capsules (containing 0.8 g of verbenone) and the second year with an envelope-like pouch (containing 5.0 g of verbe- none). The plastic capsules were deployed at a rate of 25 and 64 capsules per acre and a no capsule treatment served as control. The pouches were deployed at 30 and 50 pouches per acre and a no pouch treatment was the control. Mountain pine beetle attractants were placed on three trees at plot center to ensure insect population pressure. In neither experiment were there any observed differences in (1) number of mountain pine beetle-killed trees, (2) number of partial attacks (strip attacks), (3) number of unsuccessful attacks (pitch-outs), (4) diameter at breast height of infested trees, (5) attack height of infested trees, (6) mean distances of in- fested trees to verbenone releasers, (7) attractants located at plot center. The possible influence of stand environment is discussed as reason for lack of effectiveness. At this point, based on this and prior studies the operational use of verbenone for reducing mountain pine beetle- attacked trees in ponderosa pine forests is not advisable. Further studies on this topic should be conducted in the future as treatment technology is developed further or the appropriate release amount and timing is better understood.

Variables associated with the occurrence of Ips beetles, red turpentine beetle and wood borers in live and dead ponderosa pines with post‐fire injury

Recently, wildfires and prescribed burning have become more frequent in conifer forests of western North America. Most studies examining the impacts of insects on trees with post‐fire injury have focused on contributions to tree mortality. Few studies have examined fire‐caused injuries to estimate the probability of attack by insects. Scant data quantifying insect associations with one another, or with live and dead fire‐injured trees, are available. We examined live and dead trees with varying levels of fire injury in wildfires in Colorado, Montana, Arizona and the Black Hills aiming to determine fire injury associated with insect infestation, co‐occurrence between insects and insect association with live and dead fire‐injured trees. Bole scorch height estimated the likelihood of attack by Ips spp. Diameter at breast height, bole scorch height and crown scorch height estimated the likelihood of attack by Dendroctonus valens LeConte. Diameter at breast height and bole scorch height estimated the likelihood of attack by wood borers. Ips spp., Dendroctonus valens and wood borers were associated with one another. Ips spp. beetles and wood borers were associated with dead fire‐injured trees, whereas D. valens was often associated with live fire‐injured trees. Focusing on certain fire‐caused injuries may identify trees targeted by Ips spp. beetles, Dendroctonus valens and wood borers.

Development of post-fire crown damage mortality thresholds in ponderosa pine

Previous research has shown that crown scorch volume and crown consumption volume are the major predictors of post-fire mortality in ponderosa pine. In this study, we use piecewise logistic regression models of crown scorch data from 6633 trees in five wildfires from the Intermountain West to locate a mortality threshold at 88% scorch by volume for trees with no crown consumption. For trees with 440% crown consumption volume, linear regression indicates 485% mortality, but for trees with crown consumption volume o40%, there is a statistically significant, linear relationship between increasing crown scorch and increasing probability of mortality. Analysis of an independent 600þ tree dataset from Colorado produced similar results and supports the analysis approach. Crown scorch volume (485%), crown consumption volume (440%), and crown consumption between 5 and 40% combined with crown scorch volume 450% mortality thresholds could be incorporated into post-fire marking guidelines for forest management goals. Additionalkeywords: crown consumption,crown scorch,logisticregression, markingguidelines,piecewise regression, Pinus ponderosa, statistical models, wildfire.