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HomeMy WebLinkAboutMountain Pine Beetle Commission Memorandum REPORT TO: Honorable Mayor and City Commission FROM: Ryon Stover, City Forester SUBJECT: Mountain Pine Beetle MEETING DATE: June 15. 2009 BACKGROUND: At the June 4, 2009 Commission Policy meeting, the Commission discussed the Mountain Pine Beetle infestation, noting that there are many properties within the city that have infected trees that have not yet been removed. The issue of the cost of removing trees was raised, and it was suggested that the City Forestry Division remove infested trees on private property at no cost to the property owner. An alternative was suggested that the City Forestry Division instead treat uninfected trees on private property at a shared or reduced cost. The discussion concluded with the Commission requesting that additional information on MPBs be provided to them at the June 15th 2009 meeting. Mountain Pine Beetle (Dendroctonus ponderosae) is a native insect of the Rocky Mountain west. This particular cycle has seen beetle populations explode from New Mexico northwards to Alaska. The beetle impacts the tree in two ways, the gallery making (egg laying) disrupts the phloem tissue, and the beetle carries a Blue Stain fungus that further disrupts the vascular system of the tree. There have been previous outbreaks, in the late 1970s, but the beetle stayed in the forest. For some reason the beetle has chosen to attack trees in cities and towns throughout the region. We have seen all species of Pine attacked, and an occasional Spruce (where it has been in close proximity to an attacked Pine). The Forestry Division has done numerous events with the local media about the beetle. Since this outbreak began last summer I have done several interviews with the Chronicle, a TV spot on NBC Channel 6 News, State DNRC entomologist Amy Gannon and I did a radio call in show, I have met with neighborhood associations, Brit Fontenot has sent beetle information via e-mail to these associations, an update was presented to the Commission this past winter, I was on MT. Ag. Live in May, we have dispensed hundreds of informational articles to individuals throughout the community, and I have responded to several hundred phone calls about Mountain Pine Beetle. Numerous agencies have been working on this problem. Our working group consists of Gallatin County Conservation, DNRC, MSU, Forest Service, and private foresters. The community has done a commendable job in dealing with this insect problem. Many people have removed their infected trees and disposed of them properly. When an infected tree is found, the Forestry Division has notified the property owner and provided them with information on how to identify the tree, the pest, and how to properly dispose of the tree. 215 City Forestry crews have removed approximately 80 infected Pines from parks, cemetery, open spaces, and boulevards this past winter and spring. We will be applying the anti-aggregation pheromone, Verbenone, to the remaining Pines, on City property, that have not been attacked. The pheromone confuses the incoming beetles into thinking that the tree is already attacked and not a suitable host. In its confused state the beetle flies around until it runs out of energy and dies. We will continue to monitor trees on City property, work with homeowners, our working group of governmental agencies, and private sector tree services. I do not think it would be a good idea to go onto private property to remove beetle killed trees because there are several private tree care companies that provide this service. Also, many homeowners have already paid to have infected trees removed. As a service, at a homeowner’s request, we will consult with them on various issues on their property. We do not do the work, or recommend a particular company. I do not think it would be a good idea for us to treat private trees. In order to provide the Commission with an idea of the cost involved with removals, three companies were contacted, about the removal of two hypothetical trees. One tree was a 10”diameter, 25’ tall dead pine in the front yard. This was the “easy” access tree. The second tree was twice that size, in the backyard with no access for a lift truck, meaning the tree would have to be climbed; the limbs and stem would have to be cut in manageable pieces, and dragged out. Prices for the “easy” tree ranged from $175 to $500. The “difficult” tree ranged from $400 up to $1300. FISCAL EFFECTS: We have made a bulk purchase of the pheromone packets for $1,250. Due to the length of time the pheromone is effective, we may have to make an additional purchase later in the summer. While this was not specifically budgeted for there are sufficient funds in the operating budget to cover these purchases. If the Forestry Division were to remove trees from private property it would cause our scheduled programs, cyclic pruning, Cost Share tree planting, sight and sidewalk trimming, and service requests to be delayed. ALTERNATIVES: As suggested by the City Commission. Respectfully submitted, Ryon Stover, City Forester Chris A. Kukulski, City Manager Attachments: list the attachments Report compiled on , 2009 216 217 218 Mountain Pine Beetle (Dendroctonus ponderosae) Host: Most native and introduced species of pine trees, including lodgepole, ponderosa, whitebark, limber, and white pines. Distribution: Throughout range of pines with most notable outbreak currently in the Butte area. Identification: Reddish-orange masses of pitch (resin mixed with wood particle) on main bole; distinctive galleries apparent under bark layer with a "J" at the base; crown fading within one year of attack. Mountain Pine Beetle Mortality DNRC Pitch Tubes on Lodgepole Pine DNRC 219 Damage: Beetles feed in phloem and introduce blue- staining fungi which in combination, girdle the tree. Ecology: Bark beetles must mass attack in order to overcome a tree's natural defense mechanisms. They communicate via chemical messages, called pheromones, and can recruit other beetles by emitting a specific aggregation pheromone. As the tree becomes too full to sustain offspring, they switch to an anti-aggregation pheromone, essentially sending a "no vacancy" message to other beetles. Life Cycle: Adult beetles emerge from trees and fly between June and August, although weather and location may affect exact timing. Adults attack trees by boring under the bark and excavating a vertical gallery up to 30 inches long, laying eggs along the margins. Eggs hatch into larvae that feed on the phloem and disrupt the water and nutrient transport system of the tree. Larvae feed until cold winter temperatures initiate dormancy. Mountain pine beetles overwinter under the bark predominantly as larvae. Mountain pine beetles generally complete one gerenation per year in Montana. Management Silvicultural manipulations: Pine trees respond to mountain pine beetle by “pitching out” with pressurized resin. Therefore, thinning stands to reduce competition for light, nutrients, and water will enhance the vigor of residual trees and consequently promote resilience to beetle activity. Diversifying age classes and including tree species that do not host mountain pine beetle (such as western larch) will also minimize stand-level tree mortality. Brood trees: Identifying and removing trees currently infested with mountain pine beetle offspring can directly reduce populations in the stand. Accurate identification is critical for this tactic to be successful. Infested trees will commonly have an apparently healthy, green crown. Closer inspection might reveal pitch tubes on the bole, although these diagnostic structures are not always evident, especially in dry conditions. Pealing back the bark will expose galleries. Look for larvae, pupae, or adults under the bark to determine current infestation. Brood trees must be removed from the stand as immature beetles can successfully continue development in a cut Blue Stain in Whitebark Pine DNRC Pitch Tube DNRC Mountain Pine Beetle Galleries DNRC 220 tree. Log decks: Mountain pine beetle will continue to develop in trees even after they are cut. Therefore, it is critical to remove infested logs from the site well before the next beetle flight period (June through August) in order to inhibit dispersal. Chemical treatments: Protective chemicals are available to spray on the main bole of the tree that effectively deter mountain pine beetle infestation. Please contact the DNRC Forest Pest Management Program coordinator or a certified forest pesticide applicator to discuss this option. Pheromones: Mountain pine beetle must mass attack in order to overcome a tree’s natural defense mechanisms. They communicate via chemical messages, called pheromones, and can recruit other beetles by emitting a specific aggregation pheromone. As the tree becomes too full to sustain additional offspring, they switch to an anti-aggregation pheromone, essentially sending a “no vacancy” message to other beetles. Researchers and manufacturers have successfully manipulated the anti- aggregation chemical, verbenone, that acts as naturally occurring beetle repellant and can be used to treat small-scale acreages prone to Mountain pine beetle activity. Additional information can be requested from the manufacturers of this product. As of April 2008, there are two companies distributing verbenone capsules to the United States: Phero Tech, Inc. Synergy Semiochemical Corp. 7572 Progress Way Box 50008, South Slope RPO Delta, B. C. Canada V4G 1E9 Burnaby, B. C. Canada V5J 5G3 Phone: 604-940-9944 Phone: 604-454-1121 http://www.pherotech.com http://www.semiochemical.com Links Forest Insect and Disease Leaflet (FIDL) Field Guide - Identification Management Guide Mountain Pine Beetle Galleries with Distinctive J Hook DNRC Verbenone on Ponderosa Pine DNRC 221 Additional Common Forest Insects in Montana Douglas-fir Beetle Red Turpentine Beetle Douglas-fir Tussock Moth Spruce Beetle Fir Engraver Western Pine Beetle Mountain Pine Beetle Western Spruce Budworm Engraver Beetles (Ips species) DNRC Home Amy Gannon MT DNRC Forest Pest Management Specialist (406)542-4283 222  Colorado State University Extension. 2/99. Revised 4/07. www.ext.colostate.edu TREES & SHRUBS I N S E C T S E R I E S Mountain Pine Beetle no. 5.528 Quick Facts... Mountain pine beetles (MPB) are the most important insect pest of Colorado’s pine forests. MPB often kill large numbers of trees annually during outbreaks. Trees that are not growing vigorously due to old age, crowding, poor growing conditions, drought, fire or mechanical damage, root disease and other causes are most likely to be attacked. For a long-term remedy, thin susceptible stands. Leave well- spaced, healthy trees. For short-term controls, spray, cover, burn or peel attacked trees to kill the beetles. Preventive sprays can protect green, unattacked trees. Mountain pine beetle (MPB), Dendroctonus ponderosae, is native to the forests of western North America. Periodic outbreaks of the insect, previously called the Black Hills beetle or Rocky Mountain pine beetle, can result in losses of millions of trees. Outbreaks develop irrespective of property lines, being equally evident in wilderness areas, mountain subdivisions and back yards. Even windbreak or landscape pines many miles from the mountains can succumb to beetles imported in infested firewood. Mountain pine beetles develop in pines, particularly ponderosa, lodgepole, Scotch and limber pine. Bristlecone and pinyon pine are less commonly attacked. During early stages of an outbreak, attacks are limited largely to trees under stress from injury, poor site conditions, fire damage, overcrowding, root disease or old age. However, as beetle populations increase, MPB attacks may involve most large trees in the outbreak area. A related insect, the Douglas-fir beetle (D. pseudotsugae), occasionally damages Douglas-fir. Most often, outbreaks are associated with previous injury by fire or western spruce budworm. (See fact sheet 5.543, Western Spruce Budworms). Spruce beetle (D. rufipennis) is a pest of Engelmann and Colorado blue spruce in Colorado. Injured pines also can be attacked by the red turpentine beetle (D. valens). Mountain pine beetles and related bark beetles in the genus Dendroctonus can be distinguished from other large bark beetles in pines by the shape of the hind wing cover (Figure 1, top). In side view, it is gradually curved. The wing cover of Ips or engraver beetles, another common group of bark beetles attacking conifers, is sharply spined (Figure 1, bottom). Signs and Symptoms of MPB Attack • Popcorn-shaped masses of resin, called “pitch tubes,” on the trunk where beetle tunneling begins. Pitch tubes may be brown, pink or white (Figures 2 and 6). • Boring dust in bark crevices and on the ground immediately adjacent to the tree base. Figure 1: Adult Dendroctonus (top) versus Ips (bottom). Note gradually curved wing of Dendroctonus. Actual size of Dendroctonus from 1/8 to 1/3 inch, Ips 1/3 to 1/4 inch. by D.A. Leatherman, I. Aguayo, and T.M. Mehall 1 223 • Evidence of woodpecker feeding on trunk. Patches of bark are removed and bark flakes lie on the ground or snow below tree. • Foliage turning yellowish to reddish throughout the entire tree crown. This usually occurs eight to 10 months after a successful MPB attack. • Presence of live MPB (eggs, larvae, pupae and/or adults) as well as galleries under bark. This is the most certain indicator of infestation. A hatchet for removal of bark is needed to check trees correctly (Figures 3, 5 and 8). • Bluestained sapwood (Figure 9). Check at more than one point around the tree’s circumference. Life History and Habits Mountain pine beetle has a one- year life cycle in Colorado. In late summer, adults leave the dead, yellow- to red-needled trees in which they developed. In general, females seek out large diameter, living, green trees that they attack by tunneling under the bark. However, under epidemic or outbreak conditions, small diameter trees may also be infested. Coordinated mass attacks by many beetles are common. If successful, each beetle pair mates, forms a vertical tunnel (egg gallery) under the bark and produces about 75 eggs. Following egg hatch, larvae (grubs) tunnel away from the egg gallery, producing a characteristic feeding pattern. MPB larvae spend the winter under the bark. Larvae are able to survive the winter by metabolizing an alcohol called glycerol that acts as an antifreeze. They continue to feed in the spring and transform into pupae in June and July. Emergence of new adults can begin in mid-June and continue through September. However, the great majority of beetles exit trees during late July (lodgepole pine) and mid-August (ponderosa pine). A key part of this cycle is the ability of MPB (and other bark beetles) to transmit bluestain fungi. Spores of these fungi contaminate the bodies of adult beetles and are introduced into the tree during attack. Fungi grow within the tree and assist the beetle in killing the tree. The fungi give a blue-gray appearance to the sapwood. Infested Trees • Once MPB infests a tree, nothing practical can be done to save that tree. • Under epidemic or outbreak conditions, enough beetles can emerge from an infested tree to kill at least two, and possibly more, trees the following year. • Ips and related beetles that emerge early in summer often are mistaken for mountain Figure 2: “Pitch tubes” indicating trunk attacks by MPB. Success of the attacks is confirmed by looking under the bark with a hatchet for beetles, their tunnels and/or bluestaining. Figure 4: Mountain area infested by MPB, showing three years of mortality. Old, dead trees are gray; newly killed trees are straw yellow or orange. Some trees may also be infested but do not turn color until nine months or so under attack. Figure 6: Not all pitch tubes indicate successful attacks. Note the beetle trapped in this large pitch tube. If the majority of tubes look like this, the tree may have survived the current year’s attack. Figure 3: Top view of adult MPB (actual size, 1/8 to 1/3 inch). Figure 5: Larva of MPB (actual size, 1/8 to 1/4 inch). They are found under the bark in tunnels. 224 pine beetle, leading to early reports that “MPB is flying.” Be sure to properly identify the beetles you find associated with your trees. • Trees from which MPB have already emerged (look for numerous round, pitch- free exit holes in bark) do not need to be treated. • The direction and spread rate of a beetle infestation is impossible to predict. However, attacked trees usually are adjacent to or near previously killed trees. Control Natural controls of mountain pine beetle include woodpeckers and insects such as clerid beetles that feed on adults and larvae under the bark. However, during outbreaks these natural controls often fail to prevent additional attacks. Extreme cold temperatures also can reduce MPB populations. For winter mortality to be a significant factor, a severe freeze is necessary while the insect is in its most vulnerable stage; i.e., in the fall before the larvae have metabolized glycerols, or in late spring when the insect is molting into the pupal stage. For freezing temperatures to affect a large number of larvae during the middle of winter, temperatures of at least 30 degrees below zero (Fahrenheit) must be sustained for at least five days. Logs infested with MPB can be treated in various ways to kill developing beetles before they emerge as adults in summer. One very effective way to kill larvae developing under the bark (though very labor intensive) is by peeling away the bark, either by hand or mechanically; this exposes the larvae to unfavorable conditions—the larvae will dehydrate, starve and eventually die. Logs my also be burned or scorched in a pile—preferably when there is snow on the ground (contact your local forester for assistance). They can also be buried under at least eight inches of soil, or chipped. Following beetle emergence, wood can be used without threat to other trees. Chemical control options for MPB larvae have been greatly limited in recent years. At present, there are no labeled pesticides for use on MPB. Solar treatments may be appropriate in some areas of Colorado to reduce beetle populations in infested trees. For the treatment to be effective, the temperature under the bark much reach 110 degrees Fahrenheit or more. Such treatments can be performed with or without plastic. This method is also labor intensive; contact your local forester for more details on solar treatments. Prevention An important method of prevention involves forest management. In general, MPB prefers forests that are old and dense. Managing the forest by Figure 11: The appearance of a forest thinned to help prevent MPB. This can also improve mountain views and reduce fire hazard. Figure 7: Checking beneath the bark for MPB. This attack was successful (note tunnels and stain). Figure 9: Cut tree killed by MPB, showing the characteristic blue- staining pattern. Figure 8: Characteristic tunnels (galleries) of mountain pine beetle made by the adults and larvae. The underbark area looks like this in late spring. Bluestained wood is caused by fungi the beetles introduce. Figure 10: Large, uninfested pine being preventively sprayed. This protects high-value trees and should be done annually between April 1 and July 1. 225 Colorado State University, U.S. Department of Agriculture and Colorado counties cooperating. CSU Extension programs are available to all without discrimination. No endorsement of products mentioned is intended nor is criticism implied of products not mentioned. 1D.A. Leatherman, Colorado State Forest Service entomologist (retired); I. Aguayo, Colorado State Forest Service entomologist; and T.M. Mehall, Colorado State Forest Service forester. This fact sheet was produced in cooperation with the Colorado State Forest Service. creating diversity in age and structure with result in a healthy forest that will be more resilient and, thus, less vulnerable to MPB. Most mature Colorado forests have about twice as many trees per acre as those forests which are more resistent to MPB. Contact your local forester for more information on forest management practices. Certain formulations of carbaryl (Sevin and others) permethrin (Astro, Dragnet and others), and bifenthrin (Onyx) are registered for use to prevent attacks on individual trees. These sprays are applied to living green trees in early summer to kill or deter attacking beetles. This preventive spray is generally quite effective through one MPB flight (one year). During epidemic conditions, the pressure from beetle populations may result in less satisfactory results due to several factors: • Misidentification of healthy trees: Under dry conditions, trees may not produce pitch tubes when infested, therefore healthy trees are not as obvious. Time may need to be spent looking for sawdust around a tree’s circumference and at the base of the tree. • Timing of application: Trees sprayed after June may already have been attacked. • Improper coverage: Spray may not have been applied high enough (up to where the trunk tapers to less that six inches), or spray coverage of the tree did not begin at ground level, or was not applied to the entire circumference of the tree (thus creating “windows” for beetle attack). • Improper dosage/mixing of chemical: Low dosage—effective dosages for bark beetles are higher than the percent used for other insects. Mixture—the carbaryl and water were not fully mixed. • Environmental conditions: Significant rain or moisture within two hours of application may wash off the insecticide. Very high temperatures may break down the chemical (this can occur when treated trees are near forest fires). • Chemical shelf life/storage: Manufacturers guarantee stable chemical properties for at least two years after manufacturing date, if stored properly. Chemical properties of carbaryl may be altered if stored at very high or very low temperatures. • Improper volume/formulation: Not enough spray is used to cover the bark area susceptible to beetle attack; lodgepole pine has “flaky” bark which may require more spray. The label on the chemical does not indicate bark beetle prevention (if using Sevin, SL or XLR is recommended). Always carefully read and follow all label precautions before applying insecticides for MPB prevention. Related Fact Sheets 5.543, Western Spruce Budworms 5.558, Ips Beetles Contact the Colorado State Forest Service for additional information related to mountain pine beetles. Always carefully read and follow all label precautions before applying insecticides for MPB prevention. 226 FOR IMMEDIATE RELEASE CONTACTS: Amy Gannon, State Entomologist, Montana DNRC (406) 542-4283 Kevin Wanner, Assistant Professor, Entomology Montana State University (406) 994-5663 Ryon Stover, Bozeman City Forester (406) 582-3200 September 16, 2008 Scientists offer advice for combating Bozeman pine beetle outbreak BOZEMAN, Mont. – A coalition of entomologists and foresters tracking Bozeman’s mountain pine beetle (Dendroctonus ponderosae Hopkins) outbreak say proactive spraying of trees that haven’t been attacked is the best method for safeguarding native and ornamental pine and spruce trees in the city. “Unfortunately, once a tree has been attacked, it’s going to die,” said Amy Gannon, state entomologist with the Montana Dept. of Natural Resources and Conservation (DNRC). “Spraying trees that show signs of beetle infestation will not save them.” Gannon visited Bozeman last week to assess the beetle outbreak with Bozeman City Forester Ryon Stover, along with Kevin Wanner, MSU Extension Entomologist, DNRC Service Forester Curt Tesmer, 227 Montana Dept. of Agriculture entomologist Ian Foley, and MSU Extension diagnostician Richard Miller. The agencies and their insect specialists are collaborating on recommendations for Bozeman residents, who for months now have been watching their non-native Scotch pine turn red and die. A number of other species have also been affected – ornamental spruce, limber pine, lodgepole pine – and Gannon said native ponderosa pine and non- native Austrian pine are highly susceptible as well. Fighting the infestation requires doing battle on two fronts, said Stover: Preventing healthy trees from being attacked, and managing dead and dying trees to interrupt the beetles’ life cycle and reduce their numbers. “Mountain pine beetle larvae will continue to develop in dead standing or downed trees, including small pieces of firewood,” said DNRC’s Tesmer. Larvae become adult beetles in the summer, he said, emerging from their natal tree around mid-July to take flight and locate living trees. The adults bore into a healthy host, lay eggs, and the cycle begins anew. “It can get expensive, but people who have beetle-killed trees need to consider burning, chipping, burying or removing all of the infested wood prior to June 15,” said Gannon. “Placing a tarp over 228 infested wood doesn’t reliably kill mountain pine beetles in our climate.” Stover and Tesmer said they are looking into the possibility of a disposal yard where Bozeman residents can drop off infested logs. Healthy trees can be protected by spraying them next spring with any one of several commercial brands of insecticide, Wanner said. “Just make sure bark beetles are among the listed species on the label. Specialized equipment and precise application are critical, so hiring a certified applicator is a good idea.” Thoroughly covering the tree trunk is a key to success, he said; applications must be made on all sides of the tree from ground level up to a five-inch caliper. Another successful tool for preventing attacks is the chemical Verbenone, which mimics the “no vacancy” message that beetles send out after an infested tree has become too crowded to support any newcomers. The synthetic hormone is sealed in a permeable plastic pouch – the pouch is stapled to the tree. “Verbenone can be fairly effective in low populations,” Gannon said. “In residential areas it’s best to apply 2 – 4 pouches per tree. Be sure to follow all label instructions.” Verbenone can be ordered 229 directly from the two companies that manufacture the stuff: Pherotech (604-940-9944) and Synergy (604-454-1121). Gannon said both companies have excellent Web sites with detailed information. Identifying trees under attack by mountain pine beetles isn’t difficult. As they bore into the trunk, the tree produces popcorn- shaped nodules of sap, called “pitch tubes,” in an effort to repel the insects. Small piles of wood dust collect near the base of the tree. “Infested trees may remain green during the fall and have green crowns, but if you see pitch tubes and wood dust, that tree is done for,” said Stover, “no treatment is going to save it.” The feeding activity of the larvae will disrupt the tree’s circulatory system, he said. Beetles also carry a blue-stain fungus which has a detrimental effect on the host tree. In Bozeman, mountain pine beetles thus far have gone after ornamental Scotch pine and some spruce, said Stover, though all species of pine – ponderosa, lodgepole, limber, Austrian, mugo and whitebark – are susceptible to attack. Beetles target trees greater than five inches in diameter. ##### 230