Attack around trees treated with Verbenone was substantially lower than around both pheromone-baited and untreated control trees, amounting to just 13.5% overall.
Our results confirm that verbenone is an effective deterrent to attack by the Mountain Pine Beetle. However, they also confirm that the effect of verbenone is not absolute.
Recommendations for Panorama Town site October 2007: We conclude that the Verbenone pouch manufactured by Pherotech International is effective at reducing the risk of mass-attack by the Mountain Pine Beetle when used as directed on the label and applied at the appropriate time.
Most often-quoted, less successful studies done in 2000-2001 used much smaller Verbenone pouches. "The original pouch had 4.6 grams of active ingredient in a plastic like matrix. The new and improved Verbenone pouches have 7 grams absorbed in a sponge. The sponge provides for a more uniform release rate and the larger quantity provides for a longer lasting effect." Alan Vaudry; New Product Development Manager; Phero Tech International Inc.
Unfortunately, little testing has been done in the last 5 years. And almost NO testing has been done on higher volume packets such as those sold today. However, there are some additional factors that have been shown to affect the efficacy of the treatments - particularly in the case of Ponderosa Stands. Ponderosa forests are usually less dense than lodgepole forests. Because ponderosa pine stand structures are less dense, they probably experience higher temperatures, high solar radiation, and increased wind movement. These microclimate patterns may result in a more turbulent environment that disperses the pheromone affecting insect communication. Faster dispursal and higher release rates may cause the pouches to release too fast and may take additional treatments during the season vs. treating lodgepole forests.
It is particularly important to get the pouches as high up the tree as possible (up to 10 ft and another at 20 ft sometimes) and always on the North side (to prevent solar radiation). Wind dispersal is hard to control. If there is a way to protect the pouch from both solar and directional wind, measures should be taken to do so. ie: put the pouch on the North East side if winds typically come from the West. The trunk itself might protect the pouch from direct wind involvement. In the case of an Eastern mount, put the pouch up in the morning to see if you can shade it from Eastern morning sun. Likewise if it is mounted on North West. Mount in the evening to see shade patterns at that time of day.