摘要:

Nineteen bacteria and 11 actinomycetes isolated from various soils in which fiber flax had been grown in the Lower St. Lawrence district were found to be antagonistic toFusarium oxysporumf.lini. Among the 11 organisms forming the largest inhibition zone on agar plates, six had a fungicidal action on the spores ofF.oxysporumf.liniwhile the other five exerted a fungistatic action. Among the 19 antagonistic bacteria under trial, six induced a swelling of the germ tubes or the production of an appressoriumlike structure on agar. Green-house experiments have indicated that 15 bacteria and 11 actinomycetes offered a certain protection to seedlings some of which reached. 6, 12, and sometimes 24 in. in height before showing any signs of uniting. The organisms evidently delayed the onset of wilt symptoms, but failed to protect the plants through their entire growth.

ISSN:0008-4026    

DOI:10.1139/b53-038

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

Germinating sporidia (basidiospores) ofPuccinia graminisPers. were cytologically examined during nuclear division (mitosis) to determine the chromosome number. Studies at metaphase showed a haploid number of six chromosomes for this organism. Prophase chromosomes were observed to be united to form a continuous chain. Limits of individual chromosomes could not be seen at this stage. At metaphase, what were apparently residual terminal attractions were observed, the six chromosomes appearing as three loose pairs. The possibility of a basic chromosome number of three for this species is discussed.

ISSN:0008-4026    

DOI:10.1139/b53-039

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

Studies of cells in interphase and prophase show that at all stages of the mitotic cycle in the nuclei of Einkorn wheat and onion root tips the arrangement of the chromosomes bears a definite relation to the axis of the nucleus. The establishment, by the centromeres, of the metaphase plate is described. The observations are compared with those of previous investigators and possible applications in other fields of investigation are suggested.

ISSN:0008-4026    

DOI:10.1139/b53-040

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

A number of methods reported to be effective in the production of spores ofBotrytis tulipaegave unsuccessful results. Both macro- and microconidia were, however, obtained by growing the fungus on living tulip leaves and petals in moist chambers.Comparisonsin vitroshowed thiram and ferbam to be effective againstBotrytis tulipaeat lower concentrations than either chloranil or Vancide 51. Sodiumo-phenylphenate was intermediate at the LD95point but its probit log concentration regression line was of steeper slope than those of thiram, ferbam, or chloranil which were parallel. This parallelism is a good indication that these compounds have a similar mechanism of action. These chemicals, when applied to infested tulip bulbs, did not control botrytis blight. This failure is probably due to their inability to penetrate the outer white bulb scale and hence reach the deep-seated mycelium of the causal fungus.

ISSN:0008-4026    

DOI:10.1139/b53-041

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

The present anatomical study of sun and shade leaves of two shrub speciesMenziesia glabellaandLonicera glaucescensis an outgrowth of interest in the response of ground cover plants to increased sunlight as the result of logging operations. Leaves of both shrub species developed on plants fully exposed to the sun are smaller, thicker, more compact, with longer palisade cells, less spongy mesophyll, and thicker cuticle than comparable leaves from plants growing normally in deep shade. Evidence is given for the views that (1) differences in leaf expression are not predetermined by the environment of the bud during its formation the previous season, and (2) structural modifications that result when typical shade buds are suddenly exposed to full sunlight are merely an indication of the plasticity of leaves to light.

ISSN:0008-4026    

DOI:10.1139/b53-042

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

Soil cultures ofAlternaria raphani, a seed-borne pathogen of radish, that had become dry when four to six weeks old, were still viable after five years. The incidence of residual viable centers in cultures of four of the five wild types studied was much higher than in those of their respective variants, on the basis of colony counts from platings of 5-gm. samples diluted one-fifth. The reverse of this was true for the remaining wild type and its variant. This pair was also unique in that the wild type had been shown to possess little infectivity, whereas its variant had proved to be highly virulent. The fungus showed no change in cultural characteristics after its five-year period in dry soil, nor any loss of virulence when plants of radish, stock, and wallflower were inoculated.

ISSN:0008-4026    

DOI:10.1139/b53-043

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

Well-marked differences, involving both the patterns of moisture movement and storage, have been found to separate the water relationships of yellow birch,Betula luteaMichx., in various stages of deterioration. The cumulative results of injection studies, root excavations, and an extended survey of the trends in moisture distribution in the species over a prolonged period, suggest that the locus of action of the disease is, in the first instance, in the roots, and that excessive rootlet mortalities in apparently healthy trees constitute the initial indication of a diseased condition in the species.

ISSN:0008-4026    

DOI:10.1139/b53-044

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

The type species and some others of the generic namesSpilocaea(syn.Cycloconium,Napicladium,Basiascum),Fusicladium(syn.Megacladosporiumpro maxima parte),Passalora,Pollaccia,Hadrotrichum,Asperisporium, andDeightoniellaare illustrated and redescribed or briefly mentioned.

ISSN:0008-4026    

DOI:10.1139/b53-045

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

Characters of conidiophore and conidium development are used for the separation of some common temperate and a few tropical Hyphomycetes into eight Sections. The need for further studies on the precise method of conidium development is stressed because this promises to provide the most stable character for the classification of Fungi Imperfecti as a whole. Conidiophores and conidia of a large number of Hyphomycetes are figured to illustrate the various characters common to each Section.

ISSN:0008-4026    

DOI:10.1139/b53-046

出版商:NRC Research Press    

年代:1953

数据来源: NRC

摘要:

It is the intention of the author in the following paragraphs to discuss and describe a natural hybrid of the genusCypripedium, from Ontario, Canada, and to call itCypripedium Landoniiin honor of its discoverer. This new hybrid is considered to be a cross betweenCypripedium CalceolusL. var.parviflorumFern. and ×Cypripedium FavillianumCurtis. This conclusion is based on the variability of the staminode, of which some forty were examined in the field and in the laboratory. The included plate illustrates that these staminodes approach the shape of their parents.

ISSN:0008-4026    

DOI:10.1139/b53-047

出版商:NRC Research Press    

年代:1953

数据来源: NRC