摘要:

In this paper the symptoms of a strain of tomato streak virus 1 found in Ontario are described and are compared with those produced by tomato streak virus 1 and tobacco virus 1 on the same hosts. On tobacco, variety White Burley, Adcock, etc., the Ontario strain produces necrotic local lesions on rubbed leaves followed by systemic mottling, whereas tomato streak virus 1 generally produces necrotic local lesions only, though sometimes systemic necrosis may follow. Also, onNicotiana sylvestristhe Ontario strain gives rise to systemic mottling with necrosis following the primary necrotic local lesions, whereas tomato streak virus 1 produces primary necrotic local lesions with or without systemic necrosis. The fact that all varieties of tobacco do not react in a similar manner to either tomato streak virus 1 or the Ontario strain is shown by a comparison of symptoms on Harrow Velvet (systemic mottling only), and White Burley or Kelley's (necrotic local lesions sometimes followed by systemic necrosis). On the other hand, all varieties tested responded to inoculation with tobacco virus 1 (tomato mosaic) by production of systemic mottling with some distortion. A series of inoculations on seven varieties of tobacco grown in the field has shown thatN.tabacum, varieties Adcock, Gold Tip, White Burley and Greenwood, were killed within two weeks after inoculation with tomato streak virus 1, whereas the Ontario strain on the same varieties caused stunting with systemic mottling of leaf tissue, but did not kill the plants. Tests as to reaction to aging and heat have demonstrated that tomato streak virus 1, the Ontario strain of this virus, and tobacco virus 1, have similar properties in that each is viable after six months aging and each is rendered inactive after ten minutes at 90 °C. Immunity tests show that tobacco virus 1 immunizes plants against infection with either tomato streak virus 1 or the Ontario strain of this virus. It is suggested, therefore, that tomato streak virus 1 and the Ontario strain of the virus may be strains of tobacco virus 1.

ISSN:1923-4287    

DOI:10.1139/cjr36c-033

出版商:NRC Research Press    

年代:1936

数据来源: NRC

摘要:

Artificial inoculation of oat varieties was carried on for a period of five years. Sixty-one varieties of oats were tested in replicated plots for two years and thirteen for three years with a composite collection of inoculum of the covered smut organism,Ustilago levis(Kell. and Swingle) Mag. All gradations in reaction from high susceptibility to apparent immunity were found to exist.Dehulling the kernels previous to inoculation increased the incidence of smut approximately six times. Susceptible varieties gave relatively greater increases in smut when dehulled than did resistant varieties. The increase in smut obtained by dehulling was independent of the year in which the test was conducted.There were no significant differences in the total amount of smut obtained between any two of the seasons in which the tests were conducted but the season influenced the relative varietal reaction.Natural epidemics of halo-blight (Pseudomonas corona-faciens(Ch. Elliott) Stev.) and blast (cause unknown) provided opportunities for obtaining data on the reaction of a large number of oat varieties. Immunity from neither of these diseases was observed but marked varietal differences were noted.

ISSN:1923-4287    

DOI:10.1139/cjr36c-034

出版商:NRC Research Press    

年代:1936

数据来源: NRC

摘要:

The results of field experiments made in 1932, 1933, and 1934, to determine the effect of mechanical seed injury on the incidence of root rot caused byFusarium culmorumand on yield in wheat are presented.Successful positive attacks of Fusarium root rot were experimentally induced in field plots. The tests showed that reduced emergence, increased root rot, and reduced yield uniformly followed the planting of injured wheat seed; and that the amount of disease increased and the yield decreased with an increase in the degree of seed injury. In these experiments Mindum and Marquis wheat seemed equally affected by seed injury.The investigation suggests that the large annual losses in yield caused by root-rot diseases of cereals in Western Canada may be substantially reduced by sowing clean, vigorous, sound seed.

ISSN:1923-4287    

DOI:10.1139/cjr36c-035

出版商:NRC Research Press    

年代:1936

数据来源: NRC

摘要:

A tetraploid sector on a barley spike was induced by germinating and growing barley for seven days at 35 °C. Tetraploid and diploid florets from the same spike were compared with respect to chromosome pairing and chiasma formation.

ISSN:1923-4287    

DOI:10.1139/cjr36c-036

出版商:NRC Research Press    

年代:1936

数据来源: NRC