William R. Jacobi

Traps and Attractants for Wood-Boring Insects in Ponderosa Pine Stands in the Black Hills, South Dakota

Abstract Recent large-scale wildfires have increased populations of wood-boring insects in the Black Hills of South Dakota. Because little is known about possible impacts of wood-boring insects in the Black Hills, land managers are interested in developing monitoring techniques such as flight trapping with semiochemical baits. Two trap designs and four semiochemical attractants were tested in a recently burned ponderosa pine, Pinus ponderosa Dougl. ex Laws., forest in the Black Hills. Modified panel and funnel traps were tested in combination with the attractants, which included a woodborer standard (ethanol and α-pinene), standard plus 3-carene, standard plus ipsenol, and standard plus ipsdienol. We found that funnel traps were equally efficient or more efficient in capturing wood-boring insects than modified panel traps. Trap catches of cerambycids increased when we added the Ips spp. pheromone components (ipsenol or ipsdienol) or the host monoterpene (3-carene) to the woodborer standard. During the summers of 2003 and 2004, 18 cerambycid, 14 buprestid, and five siricid species were collected. One species of cerambycid, Monochamus clamator (LeConte), composed 49 and 40% of the 2003 and 2004 trap catches, respectively. Two other cerambycids, Acanthocinus obliquus (LeConte) and Acmaeops proteus (Kirby), also were frequently collected. Flight trap data indicated that some species were present throughout the summer, whereas others were caught only at the beginning or end of the summer.

Retail Firewood Can Transport Live Tree Pests

ABSTRACT Untreated firewood can harbor destructive insects and pathogens and transport them to uninfested areas. In a national survey of retail locations selling firewood in 18 states, over half (52%) of the firewood was from sources out of the purchase state and 50% showed evidence of insect infestation. In a three state survey of southern Rocky Mountain retailers, the most common retailer types carrying firewood were grocery stores and department or big box stores followed by gas stations or convenience stores. In 2007–2009, we purchased 419 firewood bundles from retailers in Colorado, New Mexico, Utah, and Wyoming and caged the firewood to quantify insect emergence. Live insects emerged from 47% of firewood bundles over 18 mo of rearing time. Approximately 11 insects emerged on average from each infested bundle (1–520 per bundle). Pine, fir, and mixed-conifer bundles yielded the greatest number of insects. Beetles (Coleoptera) were prominent and made up the majority of individuals (3–60 individuals in each of 24 families). Most Coleoptera were bark and ambrosia beetles (subfamily Scolytinae) while wood borers (Buprestidae, Cerambycidae, Siricidae) occurred in lower numbers. Firewood with evidence of previous or current insect infestation was more likely to have insects emerge than firewood without such evidence. The risk of moving live native or nonindigenous insects in untreated firewood is high because insects emerged up to 558 d from purchase date. Retail firewood should be heat treated in a manner to eliminate insects that is uniformly accepted across North America.

Distribution of Ribes, an alternate host of white pine blister rust, in Colorado and Wyoming

Abstract Ribes (currants and gooseberries) are alternate hosts for Cronartium ribicola, the invasive fungus that causes blister rust of white pines (Pinus, subgenus Strobus) in the Rocky Mountain region of Colorado and Wyoming. The location, species, and density of Ribes can affect the spread and impact of this potentially serious forest disease. We assessed the distribution and density of Ribes growing near white pine stands for 15 study areas in Colorado and Wyoming with 1258 survey plots of two types, an intensive white pine/Ribes survey and an extensive Ribes survey. Species present, total numbers of stems and bushes, average number of stems per bush, and average stem length were recorded. Various Ribes species were present in all study areas across a range of elevations. The most frequent and common species were R. cereum, R. inerme, R. lacustre, and R. montigenum. Densities and probabilities of occurrence were related to site variables and varied by Ribes species. The most common predictive variables included type of dominant overstory, elevation, and general plot classification such as riparian area. The predictive information provided can be utilized by tree health specialists for risk rating of forests and in planning white pine blister rust mitigation projects. We expect that other areas in Colorado and Wyoming with similar site characteristics will have similar distributions and densities of Ribes and thus have similar risks to white pine blister rust.

Wood-boring insect abundance in fire-injured ponderosa pine

1 Wood‐boring larvae in the families Cerambycidae and Buprestidae are often found in high densities in burned trees after wildland fires. They play an important role in tree decomposition, often reducing the value of salvageable timber, and represent an important avian food source. 2 Three forest areas that experienced wildfires 1–3 years previously were surveyed during the summer of 2004. Ponderosa pine trees with green, scorched and consumed needles were examined for wood borer occurrence. Within each of the three needle damage categories, the mean wood borer incidence was similar between different age fires. Trees with scorched or consumed needles had significantly more wood borers than trees with green needles. 3 Larvae collected from under tree bark were identified to family; when possible, cerambycids were identified further to Acanthocinus spp., Monochamus sp., Rhagium inquisitor (L.) and Stictoleptura canadensis (LeConte), and buprestids were identified to Chalcophora spp. and Chrysobothris sp. 4 Classification tree models showed that the estimated probability of tree infestation by wood borers varied among needle damage categories. For trees with green needles, tree injury variables of high bole char height and phloem discolouration were important predictive variables. In trees where needles were consumed, tree size variables of diameter at breast height and tree height were important predictive variables. 5 More than half the dead trees examined were infested with wood borers, indicating that infestation of fire‐killed ponderosa pine may represent an important food source for species such as woodpeckers and a potential problem for the utilization of infested trees.

Mountain Pine Beetle Host Selection Between Lodgepole and Ponderosa Pines in the Southern Rocky Mountains

Abstract Recent evidence of range expansion and host transition by mountain pine beetle (Dendroctonus ponderosae Hopkins; MPB) has suggested that MPB may not primarily breed in their natal host, but will switch hosts to an alternate tree species. As MPB populations expanded in lodgepole pine forests in the southern Rocky Mountains, we investigated the potential for movement into adjacent ponderosa pine forests. We conducted field and laboratory experiments to evaluate four aspects of MPB population dynamics and host selection behavior in the two hosts: emergence timing, sex ratios, host choice, and reproductive success. We found that peak MPB emergence from both hosts occurred simultaneously between late July and early August, and the sex ratio of emerging beetles did not differ between hosts. In two direct tests of MPB host selection, we identified a strong preference by MPB for ponderosa versus lodgepole pine. At field sites, we captured naturally emerging beetles from both natal hosts in choice arenas containing logs of both species. In the laboratory, we offered sections of bark and phloem from both species to individual insects in bioassays. In both tests, insects infested ponderosa over lodgepole pine at a ratio of almost 2: 1, regardless of natal host species. Reproductive success (offspring/female) was similar in colonized logs of both hosts. Overall, our findings suggest that MPB may exhibit equally high rates of infestation and fecundity in an alternate host under favorable conditions.

Emergence of Buprestidae, Cerambycidae, and Scolytinae (Coleoptera) from Mountain Pine Beetle-Killed and Fire-Killed Ponderosa Pines in the Black Hills, South Dakota, USA

ABSTRACT Wood borers (Coleoptera: Cerambycidae and Buprestidae) and bark beetles (Coleoptera: Curculionidae) infest ponderosa pines, Pinus ponderosa P. Lawson and C. Lawson, killed by mountain pine beetle (MPB), Dendroctonus ponderosae Hopkins, and fire. No data is available comparing wood borer and bark beetle densities or species guilds associated with MPB-killed or fire-killed trees from the Black Hills of South Dakota, USA. We compared species assemblages of wood borers (Cerambycidae and Buprestidae) and bark beetles (Dendroctonus spp. and Ips spp. (Coleoptera: Curculionidae)) emerging from bolts collected from trees that had been killed by MPB or fire one or two years prior to harvesting. Significantly more wood borers emerged from bolts of fire-killed trees than from bolts of MPB-killed trees. Wood borer density in fire-killed trees was 13.8 per m2, compared to 4.4 per m2 in MPB-killed trees. Six wood borer species, Acanthocinus obliquus (LeConte), Buprestis consularis Gory, Chrysobothris sp., Melanophila acuminata (De Geer), Monochamus clamator LeConte, and Phaenops gentilis (LeConte), emerged from fire-killed tree bolts. Four species of wood borers, A. obliquus, Rhagium inquisitor (L.), Tetropium cinnamopterum Kirby, and Xylotrechus longitarsis Casey, emerged from MPB-killed tree bolts. Acanthocinus obliquus was the only species that emerged from both MPB-killed and fire-killed tree bolts. The bark beetles D. ponderosae, Dendroctonus Valens LeConte, Ips knausi Swaine, and Ips pini (Say) emerged from one-year-old, MPB-killed trees, while I. pini was the only species that emerged from a fire-killed tree.

Monitoring surface water chemistry near magnesium chloride dust suppressant treated roads in Colorado.

Magnesium chloride (MgCl2)-based dust suppression products are commonly used throughout western United States on nonpaved roads for dust suppression and road stabilization by federal, state, and county transportation agencies. The environmental implications of annually applying these products throughout spring and summer months on adjacent stream chemistry are not known. Sixteen streams were monitored biweekly for 1 to 2 yr in two Colorado counties for a suite of water quality variables up and downstream of nonpaved roads treated with MgCl2-based dust suppression products. Eight of 16 streams had significantly higher downstream than upstream concentrations of chloride or magnesium over the entire monitoring period (p<or=0.05). Mean downstream chloride concentrations ranged from 0.17 to 36.2 mg/L and magnesium concentrations ranged from 1.06 to 12.8 mg/L. Several other ions and compounds, including those commonly found in dust suppression products such as sodium, calcium, and sulfate, were also significantly higher downstream at some sites. Downstream electrical conductivity (EC), chloride and magnesium concentrations were positively correlated with road surface area draining water toward the stream and yearly amount of MgCl2 applied (R2=0.75, 0.51 and 0.49, respectively), indicating that road managers can limit the amount of product entering roadside streams by assessing drainage characteristics and application rates in best management practices. Although MgCl2-based dust suppressants did move into some roadside streams, the concentrations detected were below those reported to adversely affect fresh water aquatic organisms, but the ultimate fate of these ions in Colorado waterbodies are not known.

Roadway Deicer Effects on the Germination of Native Grasses and Forbs

Normal seed germination of native herbaceous species can be reduced by high concentrations of deicer products and their constituent salts. Chloride salts are commonly used during the winter months in temperate climates to remove ice and snow. Although these products greatly improve driving conditions, they can have detrimental effects on the vegetation growing along highways. The purpose of this laboratory study was to determine the impact of a magnesium-based deicer product and a sodium-based deicer product and the major salts they contain on the germination and viability of several species of grasses and forbs native to Colorado and planted in revegetation seedings there. Seeds were placed on blotter paper saturated with either a water control, one of three concentrations of each of the deicing solutions, or one of three concentrations of a pure NaCl or MgCl2 solution. Increasing concentrations of salt ions generally resulted in delayed and reduced normal seed germination, especially the sodium- and magnesium-based deicer solutions. Germination for most species was lower when seeds were grown in deicer solution compared with germination percent of seeds grown in the pure salt solutions. Some species were more tolerant of one of the salts and deicers. Species with C4 photosynthetic pathway were more tolerant than C3 species of high concentrations of both deicer products. Those species which attained the highest germination percent under moderate or high solution concentrations included blue grama, buffalograss, little bluestem, mountain brome, and slender wheatgrass.

Black stain root disease progression in coastal Douglas-fir in British Columbia

Abstract Periodic monitoring of black stain root disease (Leptographium wageneri var. pseudotsugae) in coastal Douglas-fir (Pseudotsuga menziesii) on Vancouver Island and mainland British Columbia, Canada, provided intensification and mortality rates for this disease. Fifteen plots with Douglas-firs of varying ages and sizes and growing on sites with different conditions were established in 1989 and assessed in 1994 and 2000. Overall mortality from black stain root disease increased from 11.4% in 1989 to 19.0% in 2000, or 0.7% per year. A further 6.5% of trees succumbed to other root diseases and 9.4% to unknown causes but most likely black stain root disease. When trees were placed in three diameter classes, there were no significant differences in disease incidence among size classes or over time. Based on plot-level data, the incidence of disease increased with an increase in elevation (P < 0.09) and with an increase in slope (P < 0.08). Mean tree age and aspect were not significantly related to disease incidence. Crown condition rating of trees within the black stain root disease centers was a good predictor of future mortality and further disease progression. Trees with crown condition classes of slightly yellow foliage, moderately yellow foliage, totally yellow foliage, and >50% defoliated in 1989 died at a higher rate as crown condition deteriorated with 26%, 45%, 64%, and 77% tree mortality, respectively, by 2000.

Restoration planting options for limber pine (Pinus flexilis James) in the Southern Rocky Mountains1

Abstract Limber pine Pinus flexilis James populations in the southern Rocky Mountains are threatened by the combined impacts of mountain pine beetles and white pine blister rust. To develop restoration planting methods, six P. flexilis seedling planting trial sites were installed along a geographic gradient from southern Wyoming to southern Colorado. Experimental treatments included: high or low overstory canopy density from existing trees, presence/absence of a nurse object, and presence/absence of hydrogel. Of the P. flexilis seedlings planted, 72% were alive after four growing seasons. There were interactions between nurse object, seedling height at planting, and percent canopy cover that affected the number of healthy seedlings. Denser canopy cover was positively correlated with healthier planted seedlings and hydrogels had no effect. Nurse objects promoted healthier seedlings, particularly when canopy cover was low (0–50% cover), and the specific orientation to the nurse object affected seedling health under all levels of canopy cover. In conclusion, for best growth and survival in the first four years after planting, P. flexilis seedlings should be planted under an overstory canopy and on the north or west side of a nurse object, particularly if the canopy cover is low or absent.