摘要:

An outbreak of balsam fir dieback in Ontario, which was first reported in 1954, reached its peak throughout the Province in 1955 and gradually receded during subsequent years. The dieback, which involved leaders, branches, and occasionally entire trees, appeared when those parts died as the result of their proximal invasion by a fungus. Cankering usually accompanies necrosis; fruiting bodies may be produced immediately or may not appear until the spring following canker formation. The three fungi most commonly found in association with dieback,Thyronectria balsamea(Cke. & Pk.) Seel.,Dermea balsamea(Pk.) Seav., andValsa abietisFr., were shown to be independently capable of inducing typical dieback and cankering when inoculated into wounds on transplanted trees. It was further shown that adult balsam fir borer beetles (Monochamusspp.), which regularly feed on and injure twigs and branches of healthy trees, usually carry viable material of one or more of the three common fungi. The ability of the beetles to kill twigs was confirmed and it was shown that, although dieback frequently develops from wounds made by fungus-infested beetles, no dieback ensued in the absence of fungi. The outbreak is believed to have been caused by the interaction of several factors (climate, fungi, site, and insects) on the host trees.

ISSN:0008-4026    

DOI:10.1139/b61-018

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

A survey of various plant species for the ability to utilizeL-tyrosine as a lignin precursor has been extended, and the results obtained on a total of 21 species, representing seven families of monocotyledons and five of dicotyledons, are presented. Only grasses were able to convertL-tyrosine andL-phenylalanine to lignin with about equal efficiency, although two members of the Compositae and possibly one monocotyledon,Triglochin maritima, showed evidence of some ability to utilize tyrosine. One species ofJuncus, J. nodosus, was unable to use phenylalanine efficiently and another,J.balticus, yielded conflicting results with regard to the utilization of both compounds. The findings are discussed in relation to known lignification pathways and taxonomic relationships.

ISSN:0008-4026    

DOI:10.1139/b61-019

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Exposure of growing cultures to white light caused subsequent formation of a ring of conidia-bearing mycelium at the location occupied by their advancing margins at the time of irradiation. Violet and blue light were very effective in stimulating sporulation, green was less so, and yellow and red were ineffective. An exposure to white light of the order of 1 foot-candle for 1 minute sufficed to initiate the sporulation response.

ISSN:0008-4026    

DOI:10.1139/b61-020

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

P32-labelled orthophosphate was fed to rusted and non-rusted wheat leaves. The ribonucleic acid (RNA) isolated from this material was purified and its specific activity determined. The specific activity of RNA fromsusceptiblereacting tissue had increased 60–208%days after inoculation, butdays after inoculation it was not markedly different from RNA preparations of uninoculated leaf material, indicating an increase and eventual decline in RNA synthesis of the host–parasite complex. In theresistantreaction incorporation of P32into the RNA was unaltered by infection. The possible metabolic significance of these observations is discussed.

ISSN:0008-4026    

DOI:10.1139/b61-021

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Natural hybridization is occurring between two introduced thistles,Carduus acanthoidesL. andC. nutansL., in the southern half of Grey County, Ontario. The morphological variation of plants in 37 fields, including a field near Priceville previously studied in 1952, was evaluated by means of a hybrid index in 1957.Carduus nutanswas first established in the hybrid area andC. acanthoideswas introduced later, probably from the region northwest of Owen Sound, into waste land near Flesherton, where hybridization first occurred. Many large hybrid populations were found in the southern portion of Grey County and most of these hybrids were very similar toC. acanthoidesin morphology. It was concluded that there is a numerical supremacy ofacanthoides-type hybrid segregates in the hybrid area, and that such hybrids are better adapted for survival under local conditions thanC. nutansand will probably supplant the latter species.

ISSN:0008-4026    

DOI:10.1139/b61-022

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Natural inhibition of germination inA. fatuaL. involves restriction of both sugar accumulation and utilization of sugar in growth. Both these metabolic blocks are independently overcome by exogenous gibberellic acid (GA). Evidence has been found for the presence of a natural gibberellin in seeds ofA. fatuaL. The control of dormancy is probably by a gibberellin-inhibitor antagonism since at least one inhibitor has been shown to intervene specifically in sugar production and this latter effect can be reversed by GA. The evidence presented here supports the view that control of germination during the period of after-ripening is through changes in inhibitor content rather than in endogenous gibberellin.

ISSN:0008-4026    

DOI:10.1139/b61-023

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Isolates of an unidentified low-temperature basidiomycete, associated with snow mold in Western Canada, were divided into three types, A, B, and C, on the basis of their general cultural appearance. Support for this classification was obtained when representative isolates of each type were examined to determine: the effect of temperature and pH on growth; tolerance of antibiotics and HCN; ability to liberate HCN in culture and in the host plant; pathogenicity.Type A isolates grew slowly under most conditions and were least tolerant of the extremes of temperature and pH employed, moderately inhibited by antibiotics, and strongly inhibited by HCN. They produced HCN in large quantities in host plants and none in culture. They were moderately pathogenic on grass and highly pathogenic on alfalfa. Type B isolates grew somewhat more rapidly than type A, especially at the upper and lower temperatures, and grew over a wider pH range. These isolates were more tolerant of antibiotics and HCN. They produced smaller quantities of HCN than type A in infected alfalfa plants but released large amounts in culture. They were less pathogenic than type A on alfalfa but similarly pathogenic on grass. Type C isolates were fast-growing forms which were strongly inhibited by antibiotics and HCN. They did not liberate HCN under any conditions and were not pathogenic.

ISSN:0008-4026    

DOI:10.1139/b61-024

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Two collecting trips in Gaspesian Park, Quebec, during the summer of 1957, yielded a considerable number of pyrenomycetes. In this paper records of 87 species or varieties in 46 genera are presented. Two new species,Linocarpon umbelliferarumBarr andPseudomassaria foliicolaBarr, are described. Five previously described species are transferred to other genera, and the following new combinations are proposed:Gibbera cassandrae(Peck) Barr,Gibbera grumiformis(Karsten) Barr,Gibbera kalmiae(Peck) Barr,Gibberidea kalmiae(Peck) Barr, andLimacinia arctica(Woronichin) Barr.

ISSN:0008-4026    

DOI:10.1139/b61-025

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

2-Desvinyl-2-formyl-chlorophyll-a(made by permanganate oxidation of chlorophyll-a) and chlorophyll-d(isolated fromGigartina papillata) were compared. They possessed identical visible absorption spectra, formed reduction derivatives with identical spectra, and chromatographed as a single zone on a sugar column. These results provide further evidence that chlorophyll-dis 2-desvinyl-2-formyl-chlorophyll-a. Certain thalli ofG. papillatayielded chlorophyll-dwhile others yielded none. All thalli ofRhodomela larixyielded chlorophyll-dbut in extremely small amounts.

ISSN:0008-4026    

DOI:10.1139/b61-026

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Chlorophyll derivatives, sulphur, and carbon exhibit similar trends in each of two sediment cores, one from the fertile Esthwaite Water and the other from the unproductive Ennerdale Water. In Esthwaite Water maximum levels of all three constituents were reached early in the course of lake development, while in Ennerdale Water maxima were attained much later, and, in the case of chlorophyll derivatives and sulphur, were much lower than in Esthwaite. Relatively high optical densities of acetone extracts between 400 and 500 mμ suggest the presence of carotenoids in surface muds from Esthwaite Water. Much lower optical densities were recorded for this wave-length range in extracts of deeper sediments from Esthwaite and all sediments from Ennerdale. Low ratios of optical density at 410 mμ to density at 350 mμ are characteristic of surface sediments from infertile lakes such as Ennerdale Water, and of woodland soils. However, higher ratios near to those observed throughout the Esthwaite core were found in the deeper Ennerdale sediments, with the exception of the deepest sample.Ratios of chlorophyll derivatives to carbon and of sulphur to carbon were higher in the more fertile Esthwaite Water, although relatively low ratios during the earliest stages of development indicate that this lake may have been less fertile then. In Ennerdale Water the ratio of chlorophyll derivatives to carbon exhibited a much slower rise to maximum values than in Esthwaite, and these maxima were much the same as the early Esthwaite minima. The ratio of sulphur to carbon was also consistently lower in Ennerdale Water.

ISSN:0008-4026    

DOI:10.1139/b61-027

出版商:NRC Research Press    

年代:1961

数据来源: NRC