Hard pine stem rusts on lodgepole pine at a site-preparation study in sub-boreal British Columbia: effects over 24 years

Site preparation can improve lodgepole pine (Pinus contorta var. latifolia Engelm. ex S. Watson) survival and growth; however, we lack information regarding possible interactions between treatment effects and the impacts of western gall rust (Endocronartium harknessii (J.P. Moore) Y. Hirats.) and comandra blister rust (Cronartium comandrae Peck). Mechanical and burning techniques examined over 24 years at a sub-boreal British Columbia site did not significantly increase rust infection rates or characteristics relative to an untreated control. Most infection occurred before age 10 years and at heights <2 m. By age 24 years, 22% and 10% of pine had sustained at least one western gall rust or comandra blister rust stem infection, respectively, but only 4% of western gall rust infected trees were dead, compared with 60% of comandra blister rust infected trees. Exploratory regression analysis of the relationship between tree volume and percent stem encirclement and infection height suggested that volume of 24-year-old pine infected with western gall rust averaged 8% less than the corresponding volume of uninfected trees. Over 24 years, estimated stand-level, rust-related volume loss was 8.4%, with the majority due to mortality from comandra blister rust. One-fifth of estimated volume loss was provisionally attributed to growth reductions among live western gall rust infected pine.

Lodgepole pine provenances differ in chemical defense capacities against foliage and stem diseases

Maximization of lodgepole pine ( Pinus contorta Douglas ex Louden var. latifolia Engelm. ex S. Watson) growth in a future climate with increased pest activity requires an understanding of the natural variability of quantitative resistance to disease. Foliar and bark secondary metabolites from different lodgepole pine provenances (populations) were quantified and correlated with severity of foliar diseases caused by Lophodermella spp. ( Lophodermella concolor (Dearn.) Darker or Lophodermella montivaga Petre.) or Elytroderma deformans (Wier) Darker and bark diseases caused by Elytroderma or Endocronartium harknessii (J.P. Moore) Y. Hiratsuka. Greater foliar concentrations of lignin, tannins, and some phenolics were associated with increased resistance to single or multiple foliar pathogens. Bark secondary metabolites levels were generally unassociated with resistance to bark diseases. Provenances appearing to originate in ecosystems where lodgepole pine are not the dominant species generally were more susceptible to foliar diseases and had less foliar defense-associated compounds than trees from areas where pines were the dominant species, yet clear trends proved to be elusive. Regardless, pine provenances with greater foliar levels of identified defense-associated compounds should be preferred seed sources for replanting forests in areas in which foliar disease is expected to be increasingly prevalent.

Endocronartium harknessii. [Distribution map].

A new distribution map is provided for Endocronartium harknessii (J.P. Moore) Hirats. Fungi: Basidiomycota: Uredinales. Hosts: Pinus spp. Information is given on the geographical distribution in North America (Canada (Alberta, British Columbia, Manitoba, New Brunswick, Northwest Territories, Nova Scotia, Ontario, Quebec, Saskatchewan, Yukon), Mexico, USA (Arizona, California, Colorado, Idaho, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nebraska, Nevada, New Mexico, New York, North Dakota, Oregon, Pennsylvania, South Dakota, Utah, Virginia, Washington, Wisconsin, Wyoming)).

Endocronartium harknessii. [Descriptions of Fungi and Bacteria].

A description is provided for Endocronartium harknessii. Information is included on the disease caused by the organism, i.e. Western gall rust, the gall rust of Pinus species. Details are given of its transmission, geographical distribution (Canada (Alberta, British Columbia, Manitoba, New Brunswick, Northwest Territories, Nova Scotia, Ontario, Quebec, Saskatchewan and Yukon [Yukon Territory]), Mexico, USA (Alaska, Arizona, California, Colorado, Idaho, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nebraska, Nevada, New Mexico, New York, North Dakota, Oregon, Pennsylvania, South Dakota, Utah, Virginia, Washington, Wisconsin and Wyoming)) and hosts (Pinus attenuata, P. balfouriana, P. banksiana, P. canariensis, P. caribaea, P. contorta, P. coulteri, P. densiflora, P. elliottii, P. engelmannii, P. halepensis, P. insignis [Pinus radiata], P. jeffreyi, P. mugo, P. muricata, P. nigra, P. pinaster, P. ponderosa, P. radiata, P. sabiniana, P. sylvestris, P. taeda and P. thunbergiana [Pinus thunbergii]).

Predicting survival of lodgepole pine stands infected with western gall rust

The probability of lodgepole pine (Pinus contorta Dougl. ex Loud.) having main-stem galls caused by western gall rust, Endocronartium harknessii (J.P. Moore) Y. Hiratsuka, surviving to rotation is unknown. To evaluate survival, 400 galled trees with at least one stem gall and 400 trees without stem galls were measured in 1992 in two precommercially thinned stands approximately 20 years old. The survival of trees was assessed in 2003. Nonlinear regression using iteratively reweighted least squares was employed to estimate the survival of galled trees as a function of the proportion of the main stem encircled by galls. Galls encircling >79% and >91% of the stem in the two stands increased the risk of mortality relative to non-galled trees, with the risk increasing steeply with percent gall encirclement; smaller stem galls did not cause tree mortality. The 11-year pattern of survival of galled trees was similar for infections that occurred on the main stem and those that had reached the stem from a nearby branch infection. Based on an earlier model of gall expansion, 38%–43% of stem-galled trees would be expected to survive until age 80. Scribing of stem galls to prevent their expansion does not appear to be a feasible management strategy.

Effects of Spore Availability, Spore Germinability, and Shoot Susceptibility on Gall Rust Infection of Pine

Temporal changes in three factors (shoot susceptibility, spore availability, and spore germinability) were evaluated to estimate their effects on the infection of lodgepole pine (Pinus contorta var. latifolia) by Endocronartium harknessii. Germinability of rust spores from sori free of hyperparasites remained above 80% during the growing season and thus would not have significantly limited infection. In contrast, there was a slight, but statistically insignificant, increase in estimated susceptibility as infection increased from 94% of maximum at 45% shoot elongation to maximum susceptibility at 90% shoot elongation. This was followed by a precipitous decline in estimated susceptibility to 57% of maximum when shoots were 95% elongated. Spore availability was 24% of maximum when shoots were 45% elongated, and thus may have been limiting at the beginning of the growing season. At the end of the growing season, spore availability declined prior to, or simultaneous with, the decline in susceptibility. The combined effect of both factors drastically reduced the number of infections estimated to occur once shoots are more than 95% elongated. As shoots elongated, relatively more infections formed higher on the shoot, supporting the hypothesis that periderm is important in limiting infection.

Random amplified polymorphic DNA variability among geographic isolates of western gall rust fungus in Canada

Geographic variability among western gall rust (WGR) fungus (Endocronartium harknessii (J.P. Moore) Y. Hiratsuka) was studied by random amplified polymorphic DNA (RAPD). Samples were taken from lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) host at four locations in British Columbia and Alberta and from jack pine (Pinus banksiana Lamb.) host at nine locations in Alberta, Saskatchewan, Manitoba, and Ontario. Of 90 random oligonucleotide primers screened, 9 were chosen for analysis. These nine primers consistently amplified 41 sharp and reproducible RAPDs (fragments) of the WGR fungal isolates over several independent runs. Eighteen of the 41 RAPDs were polymorphic (showing the presence of both marker and null phenotypes), of which 15 could discriminate WGR isolates of lodgepole pine hosts from jack pine ones. Of these 15 RAPDs, five were unique to isolates of lodgepole and five to jack pine. The remaining five RAPDs were significantly heterogeneous in the RAPD frequency between WGR isolates of the two host origins. The RAPD pattern of WGR isolates from lodgepole pine was uniform. However, isolates from jack pine differed significantly in the frequency of four RAPDs among locations, with an east-west trend of decreasing similarity in RAPD. Analysis of molecular variance apportioned 76.3, 14.4, and 9.3% of the total RAPD variability to differences among hosts, to differences among locations within hosts, and to differences within locations, respectively. The large differentiation between WGR fungal isolates sampled in lodgepole pine and jack pine hosts might suggest that selective pressure for host specificity in sampled populations was strong.

Patógenos florestais quarentenários para o Brasil

Este trabalho resume as informações sobre os patógenos florestais registrados na lista A1, de pragas quarentenárias para a região do Comitê de Sanidade Vegetal do ConeSul (COSAVE). São apresentados aspectos como hospedeiros, sintomatologia, importância econômica e potencial de introdução e controle dos patógenos Bursaphelenchus xylophilus, Cronartium spp., Drepanopeziza populorum, Endocronartium harknessii, Erwinia salicis, Gimnosporangium spp., Mycosphaerella dearnessii, M. gibsonii e Xanthomonas populi. As principais vias de introdução destes patógenos seria na forma de sementes contaminadas ou em material para propagação vegetativa que esteja infectado. A melhor medida de controle seria o tratamento de qualquer material vegetal importado, com os produtos recomendados para o patógeno quarentenário, o plantio e quarentena pós-ingresso em estufas sob inspeção contínua, até se garantir a sanidade das mudas, antes da liberação. Os plantios comerciais brasileiros de Pinus e Populus estão aparentemente resguardados, porém não foram listados patógenos quarentenários para o gênero Eucalyptus e para a acácia-negra. Um aspecto a ser ressaltado é a necessidade de um serviço de prospecção e vigilância para a detecção precoce destes patógenos, a fim de que sejam tomadas medidas para erradicação e controle. Abstract This article summarizes data about quarantine pathogens from A1 list, from quarantine pests for COSAVE region. Aspects as hosts, symptoms, economic importance, risks of introduction and control of Bursaphelenchus xylophilus, Cronartium spp., Drepanopeziza populorum, Endocronartium harknessii, Erwinia salicis, Gimnosporangium spp., Mycosphaerella dearnessii, M. gibsonii e Xanthomonas populi are presented. The ways of pathogen introductions are by contaminated seeds and infected material for vegetative propagation. The best control measure would be treating any imported vegetal material, with recommended products for quarantine pathogen before planting, further maintaining them in greenhouses with continuous inspection, in order to guarantee health conditions for seedlings before release. Brazilian commercial plantations of Pinus and Populus are covered, but quarantine pathogens for Eucalyptus and black wattle (Acacia mearnsii) were not listed. Aspects related to vigilance should be reinforced in order to prevent the entrance of these pathogens and establish adequate measures of control.

Seedling inoculation distinguishes lodgepole pine families most and least susceptible to gall rust

Resistance of lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.) to western gall rust (Endocronartium harknessii (J.P. Moore) Y. Hiratsuka) was compared between 21-year field infection trials and inoculation of 2-month-old seedlings. The seedlings were produced from seed stored since the original field plantings. Virtually all of the seedlings from families identified as susceptible in the field produced galls in the inoculation trial, only 1% of seedlings from these families did not develop galls. Nearly half the seedlings in families classed as resistant in the field trials did not form galls 13 months after inoculation. Only one of these seedlings developed galls in the following 2 years. Seedling inoculation provides a simple early test to assess field resistance to gall rust of lodgepole pine seedlots, and an efficient way to cull at least the most susceptible ones.