摘要:

SUMMARY1The problem associated with estimation of insect activity is discussed.2A precision experiment, undertaken to investigate the nature of the egg‐laying of the American bollworm, is described. The nature of the distribution is investigated.3Correlation trials between the two counts show that the same portions of the crop retain their relative attraction to the bollworm moth over short periods.4The effect of subdivision of the area on the sampling error is analysed.5Both egg as well as plant number figures per 3‐yard length show a greater variation between than within rows.6Correlation and regression coefficients prove a very close relationship between plant number and eggs laid.7Eliminating the effect of plant number eliminates this greater variation for the first egg‐count figures. In the second count the variation between rows is still significantly greater. The reason for this is discussed.8Considerations affecting the sampling technique developed from the precision data are discussed.9The sampling method is explained and two examples are given. From the analysis of these the system is shown to sample adequately the fields and fulfills the requirements of the s

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb05559.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

SUMMARY1An investigation of the effect on potato sickness of mercuric chloride applied as a soil dressing is described.2It has been found that mercuric chloride applied 3–6 weeks prior to planting has a depressing effect on the early growth of potatoes. The variety Great Scot withstands this effect better than the varieties Majestic and Eclipse. This toxic effect is prevented by applying the chemical 3 or 4 months before planting.3The degree of infestation of the plants by the eelworm is decreased by dressing the soil with mercuric chloride. The reduction in infestation is greater the nearer the application is to the time of planting.4The reduction in eelworm infestation is accompanied by an increased yield of tubers except where plants cannot properly recover from the direct toxic effect due to mercuric chloride.5Evidence has been obtained to show that mercuric chloride does not kill the eggs within the cysts.6Mercuric chloride treatment of soil effectively prevents the fungous diseases common scab and collar rot.The writer wishes to acknowledge with thanks the assistance given by many of his colleagues, and especially to Mr W. E. Gelling and Mr J. Strachan for their help in arranging the field trials, and to Mr S. Burr and Dr W. A. Millard for their help with the mycological aspect of the investigatio

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb05560.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

SUMMARYIn this article natural signs left by muskrats and various artificial aids in detection are described and discussed. Houses and the so‐called “push‐ups” are in marshes obvious and characteristic signs. With few exceptions it is hard to state definitely whether food traces found in the field have been made by muskrat or not. Willow shoots and the stems of bulrush(Scirpus)are however bitten off in a characteristic manner. The finding of burrows is very important from the practical standpoint. Where the burrows are not superficial the Fangerstock or probing bar is employed in locating them. The footprints of the muskrat are unmistakable.A method for the identification of muskrat dung is given. This depends on the measurement of the ratio of medulla width to hair width in hairs obtained from the faeces and its comparison with that of similar hairs from water vole and brown rat. Far more hairs of the muskrat lie in the ratio limits 0–30‐0‐50 than do those of water vole and brown rat– the reverse being true of the ratio l

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb05561.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb05562.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

Book reviewed in this article:Die Fusarien. By H. W. Wollenweberand O. A. Beinking.Biological Processes in Tropical Soils. By A. StevenCokbet.Problems in Soil Microbiology. By D. WardCutlerand Lettice M. Crump.Limnology. By P. S. Welch.Plant Viruses. By KennethM. Smith.Heredity and the Ascent of Man. By C. C. Hurst.A Text‐book of Mycology. By E. A. Bessey.The Arachnida. By T. H. Savory.Garden Science. By JohnGrainger.Plant Physiology. By MeieionThoma

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb05563.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY