Scientists offer advice for combating Bozeman pine beetle outbreak
Scientists offer advice for combating Bozeman pine beetle outbreak
Scientists offer advice for combating Bozeman pine beetle outbreak
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FOR IMMEDIATE RELEASE<br />
CONTACTS:<br />
Amy Gannon, State Entomologist,<br />
Montana DNRC (406) 542-4283<br />
Kevin Wanner, Assistant Professor, Entomology<br />
Montana State University (406) 994-5663<br />
Ryon Stover, <strong>Bozeman</strong> City Forester<br />
(406) 582-3200<br />
September 16, 2008<br />
<strong>Scientists</strong> <strong>offer</strong> <strong>advice</strong> <strong>for</strong> <strong>combating</strong><br />
<strong>Bozeman</strong> <strong>pine</strong> <strong>beetle</strong> <strong>outbreak</strong><br />
BOZEMAN, Mont. – A coalition of entomologists and <strong>for</strong>esters tracking <strong>Bozeman</strong>’s<br />
mountain <strong>pine</strong> <strong>beetle</strong> (Dendroctonus ponderosae Hopkins) <strong>outbreak</strong> say proactive<br />
spraying of trees that haven’t been attacked is the best method <strong>for</strong> safeguarding<br />
native and ornamental <strong>pine</strong> and spruce trees in the city.<br />
“Un<strong>for</strong>tunately, once a tree has been attacked, it’s going to die,” said Amy Gannon,<br />
state entomologist with the Montana Dept. of Natural Resources and Conservation<br />
(DNRC). “Spraying trees that show signs of <strong>beetle</strong> infestation will not save them.”<br />
Gannon visited <strong>Bozeman</strong> last week to assess the <strong>beetle</strong> <strong>outbreak</strong> with <strong>Bozeman</strong><br />
City Forester Ryon Stover, along with Kevin Wanner, MSU Extension Entomologist,<br />
DNRC Service Forester Curt Tesmer, Montana Dept. of Agriculture entomologist Ian<br />
Foley, and MSU Extension diagnostician Richard Miller. The agencies and their<br />
insect specialists are collaborating on recommendations <strong>for</strong> <strong>Bozeman</strong> residents,<br />
who <strong>for</strong> months now have been watching their non-native Scotch <strong>pine</strong> turn red and<br />
die. A number of other species have also been affected – ornamental spruce, limber<br />
<strong>pine</strong>, lodgepole <strong>pine</strong> – and Gannon said native ponderosa <strong>pine</strong> and non-native<br />
Austrian <strong>pine</strong> are highly susceptible as well.<br />
Fighting the infestation requires doing battle on two fronts, said Stover: Preventing<br />
healthy trees from being attacked, and managing dead and dying trees to interrupt<br />
the <strong>beetle</strong>s’ life cycle and reduce their numbers.
“Mountain <strong>pine</strong> <strong>beetle</strong> larvae will continue to develop in dead standing or downed<br />
trees, including small pieces of firewood,” said DNRC’s Tesmer. Larvae become<br />
adult <strong>beetle</strong>s in the summer, he said, emerging from their natal tree around mid-<br />
July to take flight and locate living trees. The adults bore into a healthy host, lay<br />
eggs, and the cycle begins anew.<br />
“It can get expensive, but people who have <strong>beetle</strong>-killed trees need to consider<br />
burning, chipping, burying or removing all of the infested wood prior to June 15,”<br />
said Gannon. “Placing a tarp over infested wood doesn’t reliably kill mountain <strong>pine</strong><br />
<strong>beetle</strong>s in our climate.”<br />
Stover and Tesmer said they are looking into the possibility of a disposal yard where<br />
<strong>Bozeman</strong> residents can drop off infested logs.<br />
Healthy trees can be protected by spraying them next spring with any one of several<br />
commercial brands of insecticide, Wanner said. “Just make sure bark <strong>beetle</strong>s are<br />
among the listed species on the label. Specialized equipment and precise<br />
application are critical, so hiring a certified applicator is a good idea.” Thoroughly<br />
covering the tree trunk is a key to success, he said; applications must be made on<br />
all sides of the tree from ground level up to a five-inch caliper.<br />
Another successful tool <strong>for</strong> preventing attacks is the chemical Verbenone, which<br />
mimics the “no vacancy” message that <strong>beetle</strong>s send out after an infested tree has<br />
become too crowded to support any newcomers. The synthetic hormone is sealed in<br />
a permeable plastic pouch – the pouch is stapled to the tree.<br />
“Verbenone can be fairly effective in low populations,” Gannon said. “In residential<br />
areas it’s best to apply 2 – 4 pouches per tree. Be sure to follow all label<br />
instructions.” Verbenone can be ordered directly from the two companies that<br />
manufacture the stuff: Pherotech (604-940-9944) and Synergy (604-454-1121).<br />
Gannon said both companies have excellent Web sites with detailed in<strong>for</strong>mation.<br />
Identifying trees under attack by mountain <strong>pine</strong> <strong>beetle</strong>s isn’t difficult. As they bore<br />
into the trunk, the tree produces popcorn-shaped nodules of sap, called “pitch<br />
tubes,” in an ef<strong>for</strong>t to repel the insects. Small piles of wood dust collect near the<br />
base of the tree.<br />
“Infested trees may remain green during the fall and have green crowns, but if you<br />
see pitch tubes and wood dust, that tree is done <strong>for</strong>,” said Stover, “no treatment is<br />
going to save it.” The feeding activity of the larvae will disrupt the tree’s circulatory<br />
system, he said. Beetles also carry a blue-stain fungus which has a detrimental<br />
effect on the host tree.<br />
In <strong>Bozeman</strong>, mountain <strong>pine</strong> <strong>beetle</strong>s thus far have gone after ornamental Scotch<br />
<strong>pine</strong> and some spruce, said Stover, though all species of <strong>pine</strong> – ponderosa,<br />
lodgepole, limber, Austrian, mugo and whitebark – are susceptible to attack.<br />
Beetles target trees greater than five inches in diameter.