摘要:

Numbers and kinds of fungi were determined from nutrient plate and silicone slide studies from the roof of the Sun Life Building, Montreal, between September 1950 and December 1951. Exposures of plates were made in the General Electric Bacterial Air Sampler, and plates and silicone slides in the Bourdillon Slit Sampler. A total of 978 exposures was made on 113 sampling days during 16 months; 507 plates in the G. E. Sampler, 344 plates and 127 slides in the Slit Sampler. Of 40,359 colonies examined,Cladosporium,Penicillium, yeasts,Aspergillus,Alternaria, andActinomyceteswere commonest, constituting 47.7, 15.8, 10.4, 4.6, 4.2, and 2.2% of the total. The next commonest fungi werePullularia,Oöspora,Fusarium,Stemphylium,Verticillium,Rhizopus,Spicaria,Scopulariopsis,Phoma,Mucor,Botrytis,Cephalosporium,Trichoderma,Helmin-thosporium,Neurospora,Papularia,Cephalothecium,Pyrenochaeta,Zythia, andNigrospora. In addition 12 genera were infrequently found. Unidentified colonies numbered 174 and nonsporulating 3371 (8.3%). On a cubic foot basis numbers in the plates varied from 17.7 per cu. ft. in August to 0.4 per cu. ft in February.Fungus spores showed a seasonal variation with summer highs averaging 244 per cu. ft. in July to a low of 0.8 per cu. ft. in December. The most abundant spores wereCladosporium, yeasts, smuts,Fusarium,Alternaria,Venturia-like,Stemphylium, rusts,Septoria, andHelminthosporium. Hyphal fragments and pollen grains were present also. On eight occasions during the summer, readings of over 200 spores per cu. ft. were recorded, the maximum being 445 per cu. ft. on September 6, 1951.Cladosporiumin August reached a peak of 74.1 per cu. ft. and yeast cells in July had an average concentration of 100 per cu. ft.An analysis of the air masses indicated that pure polar air carried low numbers of fungi, whereas tropical air had very high numbers. Most of the air masses were modified polar air and their fungus content varied considerably. The fungi in the air over Montreal are believed to have had their origin in agricultural areas.

ISSN:0008-4026    

DOI:10.1139/b56-001

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

Empusaspecies were found on 44 different species of insects representing 20 different families from the following orders: Lepidoptera, Hymenoptera, Diptera, Qrthoptera, Coleoptera, Hemiptera, and Homoptera. The isolates without spores were identified asEmpusaby the presence of characteristic coenocytic hyphaeca. 13 μ in diameter.Empusa sphaerospermaand forms of the "E.grylli" type were the most predominant ones among the isolates with spores. Other species included:E.bullata,E.aphidis,E.erupta, andE.muscae. Two unusual forms, one fromS.aldrichi, and the other fromM.americanum,M.disstria, andM.pluviale, are described. The effectiveness ofEmpusaspecies as insect control agents is briefly mentioned.

ISSN:0008-4026    

DOI:10.1139/b56-002

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

The seed capacity of red pine cones varies from about 30 to over 110, depending on the size of the cone and its position in the tree crown, and is determined by the number of ovules that are structurally complete at the time of pollination. These ovules occur in a central "productive" region and constitute less than one-half of the total. The remaining ovules, most: of which are in the proximal part of the cone, never become structurally perfect, and do not contribute to seed production. Abortion of ovules in the productive region usually reduces seed production efficiency to 50–60%, and is accompanied mainly by withering of the nucellus in the first year and failure to produce archegonia early in the second year. The extent of ovule abortion during the first year varies indirectly with cone size, seed capacity, and height in tree.

ISSN:0008-4026    

DOI:10.1139/b56-003

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

A method of evaluating antifungal fumigants under substrate-free conditions by means of the standard dosage response curve is described. Results demonstrate the importance of relative humidity in ethylene oxide and chloropicrin fumigation.

ISSN:0008-4026    

DOI:10.1139/b56-004

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

The isolation of actinomycetes from soil or from scabby potato tubers was facilitated by a 10-min. treatment of the material from which the isolations were to be made with phenol in dilution of 1: 140. This eliminated most bacterial contaminants and reduced fungal contaminants especially those of the spreading type. Treatment of the material with higher concentrations of phenol progressively decreased the number of actinomycetes until there was no growth after treatment with 1: 70 dilution of phenol. Optimum development and maximum numbers of actinomycetes occurred when phenol-treated material was cultured on media adjusted to pH 6.5. More actinomycetes developed on glucose-asparagine agar than on Czapek's agar inoculated with phenol-treated material from scab-infected potatoes. However, when phenol-treated soil suspensions were tested, Czapek's agar was more favorable to the development of actinomycete colonies. A comparison of the phenol method with another in which sodium propionate is incorporated into the culture medium showed that the phenol method was more efficient in reducing contaminants and in permitting a larger number of actinomycete colonies to develop.

ISSN:0008-4026    

DOI:10.1139/b56-005

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

Studies are described on the laboratory detection of bacterial ring rot of potatoes caused byCorynebacterium sepedonicum(Spieckermann and Kotthoff) Skaptason and Burkholder. A cultural–microscopic procedure, involving the preincubation of aseptically removed infected material on a suitable medium, was found in general to be more reliable than direct examination of Gram-stained smears from diseased material. This was especially noticeable with lightly infected potatoes. The use of both methods would likely decrease the possibility of incorrect diagnosis. A serological method also was found to be of value in detecting ring rot in tubers and in plant extracts. Antiserum for one typical strain ofC.sepedonicum(CS850) agglutinated all strains tested, and also reacted with all infected samples examined but not with uninfected material. This organism might be used to prepare bulk antiserum for distribution to various laboratories engaged in the diagnosis of bacterial ring rot. Attempts to isolate a phage forC.sepedonicumwere unsuccessful.

ISSN:0008-4026    

DOI:10.1139/b56-006

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

Partially purified enzyme preparations of wheat leaves oxidize indoleacetic acid completely in the presence of manganese and a monohydroxyphenol or resorcinol. A characteristic feature of the oxygen uptake is an induction period followed by a rapid oxygen uptake which ceases when 1 mole of oxygen is consumed per mole indoleacetic acid added. One mole of carbon dioxide is evolved per mole indoleacetic acid. There is no lag in carbon dioxide evolution, but it is not given off anaerobically. Oxygen, blue light, and acetaldehyde overcome the induction period. Hydrogen peroxide formed in a final aerobic dehydrogenase step is utilized to provide a source of manganic ions which act as an electron acceptor in an initial oxidative step.

ISSN:0008-4026    

DOI:10.1139/b56-007

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

Meiotic chromosome behavior was described for a group of monosomic plants, including representatives of theF1and the first to seventh backcross generations. All plants were partially asynaptic. Rings-of-four were commonly seen inF1. and early backcross generations. Irregularities occurring among the progenies of monosomics were also described. These included monosomic plants which, through a process termedunivalent-shift, were deficient for chromosomes other than those deficient in their respective monosomic parents. It was concluded that the irregular karyotypes occur as a consequence of partial asynapsis in the parent monosomics.

ISSN:0008-4026    

DOI:10.1139/b56-008

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

A survey was made of the occurrence of natural hybrids between two species of introduced thistles,Carduus acanthoidesL. var.acanthoidesandC.nutansL. var.nutans, in Grey County, Ontario. The population of one field was studied in detail. Specimens were taken and their morphological variation was evaluated by means of a hybrid index. These species have different chromosome numbers:C.acanthoidcsL., 2n = 22;C.nutansL., 2n = 16. All the intervening numbers were found in the hybrids. There is a clear correlation between chromosome number and hybrid index: plants with the chromosome number of a first generation hybrid have an index intermediate between those of the parental species. The chromosome numbers of seedlings raised from seed collected from hybrid plants were determined. It was found that seedlings with the number 2n = 22 were much more frequent than those with other numbers. It is suggested that both ecological and gametic selection are acting in this area to favor production and survival of plants with the chromosome number and morphology ofC.acanthoides.

ISSN:0008-4026    

DOI:10.1139/b56-009

出版商:NRC Research Press    

年代:1956

数据来源: NRC

摘要:

Virus entities associated with necrotic ring spot, yellows, and green ring mottle of sour cherry, tatter leaf of sweet cherry, prune dwarf, and two viroses of rose have been purified and concentrated from cucumber leaves and/or peach and cherry petals and peach leaves by differential centrifugation. To prevent inactivation of the virus, thePrunustissues were homogenized with 0.1% potassium cyanide in 2.5% sodium bisulphite. Infective extracts of some of the entities were also prepared by ammonium sulphate precipitation and from aqueous chloroform–amyl-alcohol emulsion. Particles ranging from less than 10 to more than 100 mμ in diameter were observed with the electron microscope in extracts from both healthy and virus-infected sources. In the former, prepared by differential centrifugation, particles were distributed about a series of peaks at 10 mμ intervals and, in the latter, about a single mode characteristic of the entity under examination. Particles associated with different entities ranged from 28 mμ diameter for rose mosaic to 50 mμ for some tatter leaf and green ring mottle isolates. In extracts known to contain two viruses, characteristic distributions of each component of the mixture could be determined if the mean particle diameter of one virus was known and differed from that of the other entity by 5 mμ or more. Evidence based on particle characteristics, supplemented by cross protections and comparative symptomatology suggests that the necrotic ring spot virus is not necessarily involved in the etiology of cherry yellows, prune dwarf, tatter leaf, or green ring mottle.

ISSN:0008-4026    

DOI:10.1139/b56-010

出版商:NRC Research Press    

年代:1956

数据来源: NRC