摘要:

Benzenehexachloride (BHC) and its gamma isomer were toxic against bacteria that oxidize ammonia to nitrite, and those that oxidize nitrite to nitrate, in solution media inoculated with soils. They were not toxic against nitrifying bacteria in soils nor against those of a vegetable compost in solution cultures. They were also toxic against bacteria that oxidize thiosulphate in solution cultures of mineral soils. Additional organic matter reduced toxicity of the gamma isomer. The toxic component was in the benzenehexachloride and not in the "filler" materials. The gamma isomer was less effective than some other component or combination of components of the BHC. Neither the BHC nor the gamma isomer stimulated nitrification.

ISSN:0008-4026    

DOI:10.1139/b54-001

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

Benzenehexachloride (BHC), as "Gammexane" or "Benexane 50" reduced the hydrolysis of urea by mixed and pure cultures of soil bacteria in solution cultures. It suppressed the development of urea hydrolyzing bacteria in gelatine plate cultures. The reduction or suppression was apparently due to the benzenehexachloride (and not to the "filler" materials in the wettable powder), by interference with the action of the urease, as well as by preventing growth of the bacteria; the gamma isomer had no effect. BHC did not suppress nitrate production from urea in soil.

ISSN:0008-4026    

DOI:10.1139/b54-002

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

Chemical analyses of wheat stem rust uredospores before and after germination indicated that the lipid fraction was the major endogenous substrate used up during the germination. Some nitrogenous material, presumably protein, was also utilized and increase in chitin was observed during the germination. A number of commercially available metabolic intermediary compounds did not affect the respiration of germinated spores. Heavy metal enzyme inhibitors, such as cyanide and azide, strongly retarded the respiration of spores and of germinated spores. This, together with the findings that the spore material contained hematin and reacted positively to the Nadi reagent, suggested that a cytochrome system was operative in the respiration process. Compounds such as malonate, maleate, fluoride, and fluoroacetate, known to be the inhibitors of succinic dehydrogenase and related enzymes, did not show significant inhibition of the respiration of rust spores. However, pyrophosphate, another specific succinic acid dehydrogenase inhibitor, retarded carbon dioxide production. Other inhibitors, such as iodoacetate, benzoate, and arsenate, inhibited respiration appreciably.

ISSN:0008-4026    

DOI:10.1139/b54-003

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

Intensive studies were made during the past three years on the effect of barley stripe-mosaic (false stripe) on wheat and barley. The identity of this disease with the disease described and named by I. L. Conners in 1925 and reported by H. H. McKinney to be of virus origin in 1951 was established. Under both greenhouse and field conditions, infection caused chlorosis and necrosis accompanied by a marked loss of vigor. Large and statistically significant reductions in the height of crop, the yield, the kernel weight, and the grade of wheat resulted from the early inoculation of field plots, but not from late inoculation. The yield of wheat was reduced by 75% and of barley by 64%. The possibility that this disease has been a factor in the unthriftiness of certain fields of wheat is discussed.

ISSN:0008-4026    

DOI:10.1139/b54-004

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

A serological technique for differentiating between certain actinomycetes is described, in which satisfactory flocculation occurs with extracts from homogenized mycelium.

ISSN:0008-4026    

DOI:10.1139/b54-005

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

Surveys were made during the period 1947–1951 to determine the prevalence and distribution of the specialized forms (formae speciales) ofPuccinia coronataCorda which occur onRhamnus catharticaL. in Canada. From 96 aecial collections obtained in Manitoba and in Eastern Canada onR.cathartica, three distinct forms ofP.coronatawere isolated. Two of these, f. sp.avenaeand f. sp.festucae, had been isolated previously in both Europe and North America. The third form, which could not be identified with any previously described form, was pathogenic on many species of wild and cultivated grasses, as well as on many varieties of barley and rye, but was nonpathogenic on oats. It is given the designationP.coronataf. sp.secalisf. sp. nov. The uredial stage of f. sp.secalisis much darker in color than the corresponding stage of the other two forms and it can be distinguished from them quite readily. The formsavenaeandsecalisoccurred in Manitoba and Eastern Canada, while the formfestucaewas found in Eastern Canada only. In Eastern Canada the formsavenae,secalis, andfestucae, in the order named, comprised 60.6, 36.6, and 2.8% of the isolates. In Manitoba, the formavenaecomprised 16 and the formsecalis84% of the isolates.

ISSN:0008-4026    

DOI:10.1139/b54-006

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

A crude aeration precipitate of nabam was found to possess a relatively high order of fungicidal activity. Evidence is presented to show that this activity can be attributed to ethylene thiuram nonosulphide, both monomer and polymer. This substance was demonstrated on the foliage of plants sprayed with nabam and could account for its protective fungicidal action.

ISSN:0008-4026    

DOI:10.1139/b54-007

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

The oat variety Victoria has been shown by various investigators to be resistant to most races of crown rust but susceptible to a disease known as Victoria blight. This disease was observed for the first time in the United States in 1944 and in Canada in 1947. Susceptibility to this disease has been considered, by several workers, to be linked with the Victoria type of resistance to crown rust. The present investigations indicate that Victoria has more than one major gene for resistance to crown rust. These findings are based on data from a study of advanced generation selections of Victoria parentage and from inheritance studies involving varieties with the Victoria resistance to crown rust, such as Garry and R.L. 1987. Lines were obtained from Garry and fromF3populations of different crosses with the following three types of disease reactions: (1) lines susceptible to Victoria blight and resistant to all crown rust races studied, namely, races 1, 2, 3, 4, 5, 6, 24, 34, 34A. 38, 45, and 57; (2) lines resistant to Victoria blight and susceptible to crown rust races 4, 5, 34A, and 57, but resistant to the other races; (3) lines resistant to Victoria blight and susceptible to all races. Inheritance studies of three crosses, Garry × Exeter, Garry × Roxton, and Roxton × R.L. 1987, indicate that susceptibility to Victoria blight is dominant and governed by a single major gene; that resistance to races 4, 5, 34A, and 57 of crown rust is dominant and governed by a single major gene, but linked with susceptibility to Victoria blight; and that resistance to race 45, as well as races 1, 2, 3, 6. 24, 34, and 38, which appear to be similar to race 45 in inheritance, is conditioned by three dominant genes, one of which is associated, with susceptibility to Victoria blight.

ISSN:0008-4026    

DOI:10.1139/b54-008

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

Yellow laminated root rot occurs in most native conifers throughout the range of Douglas fir in British Columbia. The cause of this disease has been ascribed to a variety ofPoria weiriiMurr., or a species ofPoriadistinct fromP.weirii. The fungus grows from infected to healthy roots through physiologically weakened contacting points or fusions, and the disease is most prevalent in Douglas fir because of the common occurrence of root fusion in this species. Douglas fir is susceptible at any age over six years but individual trees show marked differences in their resistance to killing by the disease. The symptom picture varies greatly between infected trees and is directly related to the resistance shown by the individual host. Inoculum may remain viable for over 50 years in stumps and roots. The fungus does not appear to spread through the soil nor does it appear to be able to penetrate healthy bark tissue. Although the control of this disease is currently important in many localized areas, several characteristics in the behavior of the causal fungus indicate that it will become more important as management of second growth Douglas fir forests becomes more intensive.

ISSN:0008-4026    

DOI:10.1139/b54-009

出版商:NRC Research Press    

年代:1954

数据来源: NRC

摘要:

The etiology of sweet clover failures that have occurred in recent years in southwestern Ontario was investigated further through studies of the possible role of adverse environmental factors, of insects, and of pathogenic bacteria and fungi. A number of soil-borne parasites were found. They exhibited unusual parasitism at the point of initial infection and as the disease occurred in the field.Phytophthora cactorumwas found to cause the disease, and its parasitism of sweet clover was investigated. The susceptibility of the host varied sharply with its stage of development and was at a minimum in the seedling stage and greatest early in the second season's growth. Numerous lenticels on the tap roots provided natural breaks in the periderm through which the fungus probably entered. Invasion of the tissue by the fungus was intracellular in the relatively small number of instances when first season plants were attacked and was always intercellular when second season plants were attacked. The fungus sporulated when seedlings were infected and when extracts of seedlings were added to common artificial media. Mycelium of the fungus was found abundant in cortical parenchyma considerably in advance of lesions. Secondary organisms quickly followed the initial infection. Epidemiological studies of sweet clover failures indicated that outbreaks were characterized by relatively short periods of high disease incidence in the early part of the second growing season in individual clover stands. An analysis of weather data for the period during which recent epidemics occurred suggested that sustained high soil moisture in the early part of the growing season was prerequisite to epidemic outbreaks of the disease, with higher than average soil temperatures favorable as well. No phonological condition, however, seemed responsible for confining the outbreaks to the beginning of the second season of growth, which appeared to be incidental to some physiological change correlated with the developmental rhythm of the host.

ISSN:0008-4026    

DOI:10.1139/b54-010

出版商:NRC Research Press    

年代:1954

数据来源: NRC