摘要:

Interactions betweenSporormiellasimilisKhan & Cain and the blue-stain fungusOphiostomapiliferum(Fr.) H. & P. Sydow, both isolated fromPopulustremuloidesMichx. wood, were investigated.Sporormiellasimilissignificantly reduced the growth ofO.piliferumin vitro when grown in dual culture, in addition to inhibiting the growth ofO.piliferumon agar media and in liquid culture when treated with a culture filtrate ofS.similis.Ophiostomapiliferumfailed to colonizeP.tremuloideswood chips when they were preinoculated withS.similis. Ten known compounds were isolated and identified from the culture filtrate ofS.similis. These compounds showed varied fungitoxic effect againstO.piliferumat concentrations of 1 to 1000 μg/mL. The potential forS.similisas a biological control agent againstO.piliferumonP.tremuloidesis discussed.

ISSN:0045-5067    

DOI:10.1139/x94-286

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Efficient use of trembling aspen (PopulustremuloidesMichx.) is often limited by the presence of extensive decay and stain. Aspen trees with black stem galls of unknown cause reportedly have less advanced decay caused by the fungusPhellinustremulae(Bond.) Bond. & Boriss. than do adjacent trees without galls. Nine field sites having large numbers of galled aspen were surveyed for the presence ofP.tremulaeconks. Logistic regression showed that the odds of a gall tree having at least one conk was 44% of that for trees without galls, and that the occurrence of conks varied among sites and increased with increasing tree diameter. Inclusion of black galls in models used to predict decay might result in greater accuracy on sites where these galls are prevalent. Black galls may also be potential sources of biological control agents against decay-causing organisms in aspen.

ISSN:0045-5067    

DOI:10.1139/x94-287

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

The relative competitive abilities ofCalamagrostiscanadensis(Michx.) Beauv. andEpilobiumangustifoliumL. were tested in two sets of replacement series experiments. Both species were grown in monocultures and a range of mixtures in 25-cm pots. In the first set, substrates were held at either 9 or 21 °C; in the second set the pots were fertilized at high or low rates. In the 21 °C treatmentC.canadensiswas more competitive thanE.angustifolium(relative crowding coefficient forC.canadensistowardsE.angustifoliumwas 2.88), while there were little competition differences in the cool soil conditions. Under the cool soil temperatures, however,E.angustifoliumshowed higher vegetative reproduction than under the warm soil conditions. In the high nutrient conditions,C.canadensiswas more competitive thanE.angustifolium(relative crowding coefficient forC.canadensistowardsE.angustifoliumwas 5.84). There was little competition in the low nutrient experiment. These experiments indicate that if both species colonize a site simultaneously,C.canadensiswill outcompeteE.angustifoliumunder most conditions, as suggested from field observations of earlier researchers.

ISSN:0045-5067    

DOI:10.1139/x94-288

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Initial deposition and subsequent fate of herbicide residues in sugar maple (AcersaccharumMarsh.) foliage were quantified following applications of three different formulations of glyphosate (VISION®, TOUCHDOWN®, MON14420) and one formulation of triclopyr ester (RELEASE®) in a comparative field study. Maximum initial residues were 529, 773, 777, and 1630 mg of acid equivalent per kilogram dry mass, respectively. Initial foliar residues were dependent upon application rate (r2 = 0.63 to 0.87) and increased by a similar factor (233 to 313 mg•kg−1) for each kilogram per hectare applied, irrespective of formulation type. Foliar residues dissipated following a negative exponential pattern with time, rates of which varied with initial concentration. Mean times to 50% dissipation were 2 days for all glyphosate formulations, 1.5 days for triclopyr ester, and 4 days for triclopyr acid. Mean times to 90% dissipation were <16 days for glyphosate formulations, 9 days for triclopyr ester, and 33 days for triclopyr acid. Multivariate analyses of intercept and rate parameter estimates indicated significant (p = 0.02) differences in dissipation patterns among treatments. Orthogonal contrasts confirmed a priori hypotheses that glyphosate residue dissipation was independent of the salt formulation applied, and that triclopyr ester dissipated faster than either glyphosate (p = 0.004) or triclopyr acid residues (p = 0.07). Results are considered in terms of the exposure and resultant potential toxicity to forest songbirds inhabiting or foraging in treated hardwood canopies.

ISSN:0045-5067    

DOI:10.1139/x94-289

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Foliage mass and wood cross-sectional area were measured at different points of branches and stems within the living crown of Scots pine (PinussylvestrisL.) trees from sample plots, representing wide geographical variation. The measurements were taken during the period of annual minimum foliage mass. The needle mass: branch cross-sectional area ratio, measured below the lowest living whorl of sub-branches, differed among measured points and was normally lower for the uppermost branches, but also decreased in the lower canopy. The decrease at the lower canopy was hypothesized to reflect an excess water transport capacity resulting from the senesced needles. The lower ratio in the uppermost branches might be explained by M.H. Zimmermann's hypothesis that the water supply of foliage close to the stem is preferred. A similar trend in the branch area: stem area ratio was observed along the stem. There seemed to be strong geographic variation in the ratio between the total cross-sectional area of branches of the crown measured and the stem cross-sectional area below the living crown. The branch area: stem area ratio was higher in the southern stands, whereas there was no clear trend for the needle area: branch area ratio. The results are discussed in relation to the hydraulic architecture of trees.

ISSN:0045-5067    

DOI:10.1139/x94-290

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Wood X-ray densitometry (inter- and intra-ring wood density, ring width) and measurements of tracheid length were used to evaluate wood structural variability in 93 trees from 33 populations of white fir (Abiesconcolor(Gord. et Glend.) Lindl.). Individuals from populations representing the geographic range of the species had been growing for 24 years in a plantation near Placerville, California. Growth ring widths showed a clinal increase from northern Oregon to southern Californian populations, due mostly to variations in width of the earlywood. Rates of change from pith to bark in tracheid lengths and earlywood density decreased from northern Oregon to southern California, with the highest rates of change being among Utah populations. Slower rates of change in tracheid length and wood density would contribute to more uniform wood structure in these southern populations. Multivariate analyses confirmed the separation of regional groups within white fir. Results indicated that there is a differentiation between northern and southern Californian white fir, consistent with the former being ascribed toA.concolorvar.lowianaand the latter toA.concolorvar.concolor. Arizonan populations were grouped with southern Californian white fir.

ISSN:0045-5067    

DOI:10.1139/x94-291

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Parent and preflight-adult Douglas-fir beetles (DendroctonuspseudotsugaeHopk., Coleoptera: Scolytidae) were collected from felled Douglas-fir (Pseudotsugamenziesii(Mirb.) Franco) trees. Fungi isolated from the beetles included blue-stain fungi, such asOphiostomapseudotsugae(Rumbold) von Arx,LeptographiumterebrantisBarras & Perry, andLeptographiumabietinum(Peck) Wingfield; other ascomycetes, such asGraphiumspp. andLeptographiumspp.; yeasts; and unidentified basidiomycetes. All fungal cultures derived from parent beetles, preflight adults, beetle eggs, larvae, frass, and bark from galleries had yeasts present.Ophiostomapseudotsugaewas isolated from 67% of the parent females, 19% of the parent males, and 100% of the preflight adults of both sexes collected from their pupal cells. Rinsing the beetles with 70% ethanol prior to fungus isolations reduced the frequency of all fungi, except yeasts. Parent and preflight adult beetles (of both sexes) were examined with a scanning electron microscope, where spores ofO.pseudotsugaewere visible in shallow pits on the elytra of both male and female beetles. Spores of other fungi were observed in shallow pits on elytra and in much smaller but deeper pits on the scutellum of both sexes. The results indicate a close association between Douglas-fir beetles and fungi, accompanied by anatomical differentiation on the beetles that allows the dissemination of blue-stain fungi to new Douglas-fir hosts and substrates.

ISSN:0045-5067    

DOI:10.1139/x94-292

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Fraser fir,Abiesfraseri(Pursh) Poir., seedlings were grown in the greenhouse and at four field sites in the southern Appalachian Mountains to study the effects of infestation by the balsam woolly adelgid (BWA),Adelgespiceae(Ratz.). Swelling in the main stem was used as an indicator of abnormal wood (i.e., "rotholz") production induced by infestation. At three of the four field sites, the main stems of infested seedlings were significantly more swollen than those of uninfested seedlings. The amount of swelling caused by BWA generally was not affected by seed source (half-sib family), soil source (soil from higher or lower elevations), or interactions of these variables. At two of four field sites, infestation was associated with a significant increase in root:shoot ratio. Variability in root:shoot ratios and total dry weights of seedlings was influenced by interactions of infestation, soil source, and seed source. This result demonstrates that both tree genetics and environment play a significant role in the growth responses of infested Fraser fir seedlings. Results from the greenhouse study indicated that BWA might be represented by two or more biotypes in the southern Appalachians. Shoot weights and diameter increases were relatively large for Mount Mitchell seedlings infested by BWA from Mount Rogers, and relatively small when infested by BWA from Mount Mitchell. For seedlings from Mount Rogers, the converse was true. Overall, these results suggest that environment is probably more important than tree or insect genetics in explaining why so many infested trees have died in the Black Mountains of North Carolina.

ISSN:0045-5067    

DOI:10.1139/x94-293

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

Fraser fir (Abiesfraseri(Pursh) Poir.) seedlings were artificially infested with balsam woolly adelgid,Adelgespiceae(Ratz.), then subjected to drought-stress treatments. Infestation caused a distinct swelling in the main stem, caused by the accumulation of abnormal wood (i.e., "rotholz"). As expected, drought stress reduced diameter growth in the main stem. However, the reduction in wood increment caused by drought stress was relatively small for infested seedlings as compared with uninfested seedlings, owing to the production of rotholz. This implies that infested trees expend considerable energy and nutrients for the production of poorly functioning wood even during periods of stress. The implications of this research for interpreting patterns of tree mortality in the southern Appalachian Mountains are discussed.

ISSN:0045-5067    

DOI:10.1139/x94-294

出版商:NRC Research Press    

年代:1994

数据来源: NRC

摘要:

not available

ISSN:0045-5067    

DOI:10.1139/x94-295

出版商:NRC Research Press    

年代:1994

数据来源: NRC