摘要:

Mealy bugs,Pseudococcussp., (or spp.) have been shown to be primarily responsible for symptoms which for a number of years have been appearing on strawberry plants grown in the greenhouse, and which in certain respects bear strong resemblance to those of plants affected with the virus disease, Crinkle. The symptoms of the two troubles show similarity, not only in the occurrence on younger leaves of small, circular to irregularly-shaped translucent spots with more intensely chlorotic central portions, but also in the unevenly chlorotic character and malformation of older leaves and in the ultimate general dwarfing of heavily infested plants.

ISSN:1923-4287    

DOI:10.1139/cjr39c-020

出版商:NRC Research Press    

年代:1939

数据来源: NRC

摘要:

The mean annual nitrogen absorption (lb./acre) of hay crops (excluding roots and stubble) was: alfalfa, 94.9; timothy, 39.5; western rye, 62.9; brome, 61.1. For entire hay plants to plow depth, based on sods one and three years old, the corresponding figures were: 241.8, 152.2, 137.8, 154.2. For entire wheat plants following one-, three-, and five-year-old sods of these hay crops for six, four, and two successive years, respectively, the mean values were: 63.4, 58.6, 56.3, 51.9. These figures are taken to indicate roughly the relative rates of soil nitrification under and after the crops in question, except under alfalfa, a legume.The roots and stubble of the hay plants contained about 71% of the dry matter and 68% of the nitrogen of these plants, whereas the wheat roots and stubble contained only 19% of the dry matter and 9% of the nitrogen of these plants.Preceding crops and seasonal conditions, especially the latter, affected the protein content and hardness of the wheat grain. Protein content of grain was generally, though not invariably, in the same relative order as indicated rates of soil nitrification after the four hay crops. Protein content was related quantitatively to hardness of grain and to loaf volume of bread, but there was no evidence of qualitative differences in the protein following the various hay crops.

ISSN:1923-4287    

DOI:10.1139/cjr39c-021

出版商:NRC Research Press    

年代:1939

数据来源: NRC

摘要:

A foliage disease ofPopulus tacamahacaMill., caused by a fungus that has been given the nameLinospora tetrasporan. sp., is known to occur in Alberta British Columbia, Ontario, and Quebec, Canada. The lesions on the leaves are of various sizes, dark brown in colour, with very irregular and diffused margins. The leaves may be completely invaded, discoloured, and dropped prematurely. Small, black, circular or irregular pseudoclypei develop on the upper surface of the infected leaves. No true conidial stage was found in the life history. Spermatia are produced in acervuli that develop in the cells of the upper epidermis during late summer and autumn. Isolations from ascospores and plantings of infected leaf tissues gave similar mycelial growth on potato dextrose agar. The pathogenicity of the fungus was demonstrated by the inoculation of healthy leaves with a suspension of ascospores. Symptoms typical of the disease developed in about a month. The fungus was re-isolated from the inoculated leaves.

ISSN:1923-4287    

DOI:10.1139/cjr39c-022

出版商:NRC Research Press    

年代:1939

数据来源: NRC