摘要:

Sections of stems ofSilene cucubalus, Galeopsis tetrahit, andPhaseolus vulgariswere cultured under sterile conditions in media containing inorganic salts, sucrose, agar, and the herbicides 2-methyl, 4-chlorophenoxyacetic acid, 2,4-dichlorophenoxyacetic acid, or 2-(2,4,5-trichlorophenoxy)propionic acid. The herbicide which gave the most effective control of a species under field conditions was also the most active in inducing root formation and proliferation on stem sections of that species. The response of the sections to these auxin herbicides diminished as the plants from which the sections were taken became more mature. The amount of herbicide recovered from treated shoots of these species was not correlated with susceptibility. It is postulated that susceptibility to these materials depends upon (i) the affinity of the species for the molecular configuration of the herbicide and (ii) the relative amount and functional importance of the susceptible tissues at the time of treatment.

ISSN:0008-4026    

DOI:10.1139/b62-135

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

In the opinion of the authors, the genusCardariacontains five species. They are described and a key is given. Two taxa are transferred fromLepidiumtoCardaria, asC.PROPINQUUMand its varietyAURICULATUM. Chromosome numbers reported forC. chalepensis, 2n = 80 andC. pubescens, 2n = 16, are new, as are those of naturally occurring and previously unrecognized hybrids betweenC. chalepensisandC. draba, 2n = 64. Three species,C. draba, C. chalepensis, andC. pubescens, are introductions to North America, where they have become prominent agricultural weeds. The morphological and specific limits of these three species are discussed in detail.

ISSN:0008-4026    

DOI:10.1139/b62-136

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

In the industrialized Saint Lawrence Valley, Quebec, the climax vegetation is rather well preserved on the Monteregian Hills, a series of eight small mountains east of Montreal. The bryological flora of one of these monadnocks, Mount Yamaska, has been intensively studied. Typical bryophytes from several habitats were investigated. Growth forms and their biological spectrum on two substrata were analyzed. Finally the author has catalogued over 220 bryophyte taxa for this small (sq. miles) area.

ISSN:0008-4026    

DOI:10.1139/b62-137

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Agropyronmosaic virus (AMV) is common onAgropyron repens(L.) Beauv. in southern Ontario and Quebec and has been found on Prince Edward Island and in southeastern Saskatchewan. It was also found on a few winter wheat plants in many fields in southern Ontario each year since 1957, and on spring wheat in Saskatchewan in 1961. AMV has not appeared to be economically important, but the occasional high incidence of infection in wheat near diseasedA. repensand the fact that infected plants were sometimes severely stunted have indicated that it could be important under favorable conditions.Wheat was more susceptible thanA. repens, or any of the other hosts tested. Usually all wheat plants became infected when inoculated with sap of diseased plants diluted 1:64, and 50% became infected with dilutions of 1:256. Symptoms appeared in 6 days at temperatures of 20° and 25 °C, but were most pronounced at 15 °C. No symptoms developed on wheat kept at 10° or 35 °C for 19 days after inoculation, but sap from these plants was infectious.All isolates of AMV obtained fromA. repensand most from naturally diseased wheat caused only mild symptoms on wheat, but some isolates from wheat caused severe chlorosis and stunting. In field tests, manual inoculation with severe isolates reduced yields of spring wheat 25% to 75%, and of winter wheat up to 42%. Up to 100% of the winter wheat plants in small plots sown near naturally diseased wheat during June to late August became infected, illustrating that AMV can be perpetuated on immature wheat. Less infection developed in plots sown in September or later.Eriophyid mites, includingAceria tulipae(K.),Abacarus hystrix(Nal.), andVasates mckenzieiK. were present on naturally diseased plants, but none of these mites has been proved a vector of AMV.

ISSN:0008-4026    

DOI:10.1139/b62-138

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Discovery of rust-resistant sunflower seedlings in 1952 made it possible to distinguish races ofPuccinia helianthiSchw. occurring on cultivated sunflowers (Helianthus annuusL.). The races isolated in 1954 helped to identify two discrete factors for resistance derived from wild annual sunflowers from the Renner, Texas, area. The four races which theoretically could be distinguished with two resistance factors have all been found in Manitoba. Collections from other provinces, countries, and continents, with few exceptions were classified on the Canadian differentials as race 1. Differences among isolates of race 1 were observed on resistant derivatives ofH. argophyllusT. and G. Use of the four rust races described made it possible to identify different factors for resistance in sister selections of sunflowers with identical rust reactions in the field, and to demonstrate that the original rust resistant accessions 953-88 and 953-102 each contained at least two distinct resistance factors. Use of the races has also made it possible to recognize the existence inH. argophyllusof factors for rust resistance which appear to differ from those in the Canadian differential varieties.

ISSN:0008-4026    

DOI:10.1139/b62-139

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Heartwood of balsam fir (Abies balsamea(L.) Mill.) has been found highly selective forStereum sanguinolentumAlb. & Schw. ex Fr. and other primary invaders of this host. In tests with a number of species of fungi, including several important tree pathogens, this substrate exhibited fungus-inhibitory properties hitherto unsuspected on the basis of tests with heat-sterilized material. Tests have shown that the inhibitory property is more active in heart-wood than in sapwood, is substantially reduced by wet heat (hour at 100 °C), and is relatively unaffected by dry storage (3 years at room temperature). The selective action did not depend upon the microbiological condition of the wood.

ISSN:0008-4026    

DOI:10.1139/b62-140

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Observations on the development ofCeratocystis ulmi(Buism.) C. Moreau show that the fungus produces large numbers of spores (microspores) as small as 0.5 μ in diameter in the xylem of American elms (Ulmus americanaL.). The development of microspores has been followed from their germination into fine, short hyphae to their formation endogenously and exogenously in association with mature hyphae and spores.

ISSN:0008-4026    

DOI:10.1139/b62-141

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Cultural interaction between paired clones A and C ofF. oxysporumf.cubenseon peptone dextrose agar was a reliable tool for identification of these clones. Cultural interaction consisted of the formation of two bands of dense mycelial growth. The first and largest band formed in clone C colonies back of the tips of the outermost hyphae in contact with adjacent clone A colonies. A second much smaller band formed with clone C hyphae outside of and adjacent to the large band. The smaller band sometimes merged with the larger. This specific band reaction was distinct from a non-specific "interaction" occurring on rice agar. Mutants were produced by clones A and C, which reacted with the parents by the formation of a single band of raised, dense mycelia. These reactions were unstable and non-specific. Cultural interaction was erratic and often poorly defined with ropy mutants of clones A and C. Cultural interaction with clone A readily identified clone C from banana roots from areas where a locus of infection had been initiated by inoculation 3 years previously. Thus, cultural interaction was useful in "tagging"F. oxysporumf.cubensefor studies with mixed indigenous soil populations ofF. oxysporum.‘Odoratum’ and ‘Inodoratum’ clones (readily separated by smell on steamed rice) were subjected to gas chromatography. All 'Odoratum' cultures gave a characteristic spectrum showing qualitative and quantitative differences from the 'Inodoratum' cultivar in volatiles produced. The characteristic 'Odoratum' smell after 7 days on steamed rice was associated with a spectrum not shown by 'Inodoratum' clones.

ISSN:0008-4026    

DOI:10.1139/b62-142

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Pieces of propylene oxide fumigated banana leaves, and detached roots ofMusa balbisiana, were used as substrates to study the colonizing ability ofF. oxysporumf.cubenseclone C in competition with the natural flora of different soils. Populations of clone C ranging from about 5000 to 100,000 spores per gram of soil colonized in 3 days a variable but low percentage of baits, usually being recovered from less than 20% of the leaf and root fragments sampled. Colonization of leaf baits also occurred in submerged soils containing 60,000 or more spores per gram of clone C, but was reduced one-half or more in comparison with non-submerged soil. In Honduras banana soil,F. solani, Rhizoctoniaspp., and sometimesRhizopusspp. were dominant colonizers. SaprophyticF. oxysporumwas also recovered from some of the baits along with clone C. Clone C was recovered from a small percentage of grass roots colonized in situ. In diseased banana plants, clone C was a predominant colonizer of portions of about 20% of the decaying main roots. Colonization presumably occurred outward into the decaying cortex from a parasitically established base in the infected stele.In banana soilsF. oxysporumf.cubense, even at populations of 100,000 per gram of soil, was a weak competitor in comparison withF. solaniandRhizoctoniaspp. at natural populations of less than 2000 per gram of soil. Natural populations ofF. solaniandF. roseumdominatedF. oxysporumin general in saprophytic competition for various substrates. Nevertheless, the results showed thatF. oxysporumf.cubensemust at times take advantage of favorable micro-environments to successfully invade a small percentage of colonizable sites on roots and other substrates. In these instances, the banana wilt pathogen has probably escaped competition with more vigorousFusariumand other saprophytes because of random spore distribution in soil.

ISSN:0008-4026    

DOI:10.1139/b62-143

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Cyathus earleiLloyd is a Bird's Nest Fungus previously known chiefly from the American tropics. A more recent collection from Mexico is described and compared with older herbarium material. The Mexican collection yielded viable spores and this made possible a study of the fungus in culture. It shows marked similarity toC. ollaPers. in the mode of spore germination and the appearance of mycelium. Attempts to obtain hyphal fusions between mycelia ofC. earleiandC. ollawere unsuccessful;C. earleiis believed to be a distinct species although closely related toC. olla.

ISSN:0008-4026    

DOI:10.1139/b62-144

出版商:NRC Research Press    

年代:1962

数据来源: NRC