摘要:

Transmission of potato leaf roll and turnip latent viruses byMyzus persicae(Sulz.) were similar in that: (a) fasting aphids for 18 hours prior to inoculation feeding had no effect on the numbers that transmitted virus; (b) upper and lower surfaces of infected leaves ofPhysalis floridanaRydb. were equally good sources of virus; (c) top leaves of infected plants were better sources of virus than middle or bottom ones; (d) excised leaves were better sources of virus than whole plants for short acquisition feeding periods but not for longer ones; (e) when infective aphids fed on a small area of a leaf, they transmitted virus as often as those that fed on whole plants; (f) and more nymphs transmitted virus than adults.The transmission of the two viruses differed in that: (a) during comparable acquisition and inoculation feeding periods more aphids transmitted potato leaf roll than turnip latent virus; (b) fasting aphids for 18 hours prior to acquisition feeding had no effect on the numbers that transmitted potato leaf roll, but increased the numbers that transmitted turnip latent virus; (c) and three- or six-leafP. floridanawere equally good test plants for potato leaf roll, but more three-leaf ones became infected with turnip latent virus.

ISSN:0008-4026    

DOI:10.1139/b62-049

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

The pectic enzymes produced byFusarium oxysporumf.lycopersiciappear to be causally related to the virulence of the pathogen. The effects of various cultural conditions on the synthesis of pectin methylesterase by two strains of the pathogen were investigated. The virulent strain grew better and produced more pectic enzymes than the avirulent one, and this difference became even more pronounced in media with high pectin content and when the temperature of incubation was raised from 15° to 28 °C. The correlation between the virulence of the pathogen and the production of the pectic enzymes is discussed.

ISSN:0008-4026    

DOI:10.1139/b62-050

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Forty-one species of weeds were found to be hosts of the northern root-knot nematode,Meloidogyne haplaChitwood, 1949, in Ontario. Variation in the size of the small galls caused by the nematode was correlated with the thickness of the root of the host. Abnormally large galls found on a few species of weeds were due to multiple infections by the nematode.

ISSN:0008-4026    

DOI:10.1139/b62-051

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Supernumerary chromosomes were present in two diploid introductions of crested wheatgrass but absent in the diploid variety Fairway. In five tetraploid populations, they were present in 36.9 to 88.5% of the plants.Diploid plants contained supernumerary chromosomes in pollen mother cells, in primary roots, and in stem tissues, but not in adventitious roots. Supernumeraries in crested wheatgrass were usually smaller than basic chromosomes and they were not heterochromatic. There was good pairing between supernumeraries but not between supernumerary and A-chromosomes. Transmission of supernumeraries through the egg generally occurred in haploid numbers. In pollen, directed non-disjunction of supernumeraries towards the gametes took place with an average frequency of approximately 70%. The degree of transmission depended to some extent on the genotype of the parent and on the numbers of supernumeraries involved. Elimination of supernumeraries from reproductive tissues was generally low but became more pronounced at higher frequencies.

ISSN:0008-4026    

DOI:10.1139/b62-052

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

The synthesis of ureides was studied in root, stem, and leaf tissues, as well as in intact seedlings, of silver maple (Acer saccharinumL.) using radiotracer techniques. Ureide synthesis was demonstrated from carbon-14 labeled adenine, glycine, formate, urea, and bicarbonate. Ureide synthesis from adenine apparently followed the degradative pathways previously known in animal tissues. Synthesis of ureides from glycine, formate, urea, and bicarbonate appeared to be via a purine precursor, probably inosinic acid or a closely related compound. The experimental methods were not discriminating enough to demonstrate whether ureides are normally synthesized in the roots and translocated to the tops of maple seedlings.

ISSN:0008-4026    

DOI:10.1139/b62-053

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

One hundred mosses and seven liverworts are reported from the Cypress Hills of southwestern Alberta and southeastern Saskatchewan. Included are 11 bryophytes not previously reported from Saskatchewan and 6 new to Alberta. Of special interest was the discovery ofScapania carinthiaca, known previously from two North American stations and a few in Europe and Siberia. Also interesting was the collection ofDicranum drummondiiandMnium drummondii, both of which are seldom encountered and are restricted to a central North American distribution pattern. Chromosome counts were made from material ofAtrichum undulatumvar.altecristatum(n = 7),Atrichum selwynii(n = 7), andPlagiothecium turfaceum(n = 11). The ecology and elements of the area are discussed. A montane element of 9.1% was found to exist in the moss flora.

ISSN:0008-4026    

DOI:10.1139/b62-054

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Four new species ofOidiodendron, viz.O. truncatum, O. maius, O. citrinum, andO. echinulatum, are described from soil. One new combination,O. cerealis(Thum.) Barron, is proposed and an emended description ofO. flavumSzilvinyi presented.O. fuscumRobak is considered to be conspecific with the priorO. tenuissimum(Peck) Hughes.

ISSN:0008-4026    

DOI:10.1139/b62-055

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

A complex of fungi was isolated from lodgepole pine (Pinus contortaDougl. var.latifoliaEngelm.) at various stages of mountain pine beetle (Dendroctonus monticolaeHopk.) attack.Ceratocystis montiaRumb.,Leptographiumsp.,Pichia pini(Hoist) Phaff,Hansenula holstiiWickerham,Hansenula capsulataWickerham, and some unnamed yeasts were isolated from beetles, fresh galleries, and blue-stained sapwood. Perithecia ofC. montia, Ceratocystis minor(Hedgc.) Hunt,Ceratocystis minuta(Siem.) Hunt,Ceratocystissp., andEurophiumsp. were found on the bark and sapwood of dead, blue-stained trees. Beetles are conclusively shown to be vectors of blue stain fungi. The known ranges ofC. montiaandP. piniare extended by this study and a possible succession of organisms associated with the development of beetle infestation is discussed.

ISSN:0008-4026    

DOI:10.1139/b62-056

出版商:NRC Research Press    

年代:1962

数据来源: NRC

摘要:

Poplar trees with decay typical of that caused byFomes igniarius, or with extensive stain, were dissected and several hundred platings made from each. Sixty-three different fungi were isolated, as many as 20 from a single tree. Most of the fungi were widely distributed in the tree with no consistent association with any stage of decay. Different zones of decay yielded 19 to 36 fungi each, the zone of early incipient decay giving the largest number. Bacteria were isolated from every zone.Trees with stain but no decay yielded 24 fungi, 15 of which were also found in the decayed trees. Many of these were clearly precursors ofF. igniarius. Several pockets of typical decay did not yieldF. igniarius, suggesting that it had been killed out by competition.The pH of water extracts of wood from various zones of decay was highly variable, the minimum range for a zone being pH 4.8 to pH 8.8, and the maximum range pH 3.8 to pH 9.4. The implications of these variations are discussed.Effects of various media, and of frozen storage prior to making isolations, were studied.

ISSN:0008-4026    

DOI:10.1139/b62-057

出版商:NRC Research Press    

年代:1962

数据来源: NRC

ISSN:0008-4026    

DOI:10.1139/b62-058

出版商:NRC Research Press    

年代:1962

数据来源: NRC