ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1944.tb06200.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

Cotton wilt of physiological origin appears to have been present in the Gezira area of the Anglo‐Egyptian Sudan since 1924 if not previously. The present investigations showed that between mid‐October and mid‐December three factors occur which cause water stress in the crop. At some time during this period there is marked reduction in the size of the absorbing system of the plant, correlated with maximum boll development. Greatly increased day temperatures and higher evaporation prevail, while during the whole period available water in the soil declines. The hypothesis is put forward that when all three factors occur at the same time at their maximum intensity, permanent wilting and death of the plants result; at lesser intensities, wilting is followed by recovery, but with reduction of yield. Experiments are described, the results of which appear to confirm this view. In the author's opinion a return to the earlier sowing date formerly favoured locally would lead to considerably increased l

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1944.tb06201.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

Sand‐culture experiments with the pea plant demonstrated that 8.24–32.96 p.p.m. of available nitrogen was the optimum range of concentrations for yield of peas, with a bias in favour of the lower half of the range; adequate supplies of nitrogen appeared to cause branching of the tops into two or more main stems. The best range of concentrations of available phosphorus was 2.73‐10.92 p.p.m., while that for available potassium was 5.61‐44.88 p.p.m. Deficiency of potassium caused marginal scorch followed by general scorch and death of the foliage progressively up the stem. Absence of boron had not a great effect with this plant, probably because the large seed possibly contains an appreciable amount o

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1944.tb06202.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

The yield data available from the author's series of investigations on vegetable nutrition in sand have been plotted against the concentrations of the elements concerned (nitrogen, phosphorus, and potassium), and the curves so obtained have been discussed. Within the ranges of concentrations employed, it is observed that too much available nitrogen or, especially, available phosphorus, causes depressions in yields with the tops and/or roots of certain vegetables, turnip roots being particularly susceptible to too much available phosphorus; no case of over‐employment of available potassium, however, is noted. The turnip is recommended as a type plant for indicating the state of soil fertility as regards available (nitric) nitroge

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1944.tb06203.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

Stocks of narcissi infected withFusarium bulbigenumwere divided into two parts, of which one was given the standard hot‐water treatment and the other was hot‐water treated with the addition of 0.5% formalin to the water. Some stocks were lifted the following season and the treatment was repeated. With most stocks a single application of formalin was sufficient to reduce the amount of disease to negligible proportions, but with one heavily infected stock a second treatment was necess

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1944.tb06204.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

Potato virusB, and some other viruses with reactions in potato varieties different from any previously described, are strains of virusX. All produce intracellular inclusions which vary with different hosts and virus strains. Except with virus B, the inclusions are larger and more frequent in potato than in tobacco or tomato. All give systemic infection when inoculated to tobacco, tomato and potato varieties in which they are carried or cause mosaic symptoms; some give systemic infection when inoculated to varieties in which they cause top‐necrosis, whereas others give only local lesions.Potato virus C is a strain of virus Y: in tobacco and a few potato varieties both produce similar symptoms, but in those varieties in whichYcauses leaf‐drop streak,Ccauses top‐necrosis.Ccauses systemic infection when inoculated to tobacco and to potato varieties in which it causes mosaic symptoms, but not when inoculated to potato varieties in which it causes top‐necrosis. VirusCwas not transmitted byM. persicae. VirusesCandYproduce a few small intracellular inclusions in potato and tobacco.VirusAis not related toYorX: no inclusions were found in plants infected wit

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1944.tb06205.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

A virus disease of tea in the up‐country districts of Ceylon is described which is known as ‘phloem necrosis’ from the characteristic internal symptoms. External symptoms including leaf curl and zigzag and dwarfing of the shoots are of less constant occurrence and appear to be much influenced by climatic and growth conditions generally. Severely affected bushes are rendered entirely unproductive. The disease is shown to be transmissible by grafting to certain types of tea, nine clones of various origin having been infected so far. In others, of the type commercially favoured for replanting, no symptoms are produced. These have proved to be symptomless ‘carriers’ capable of transmitting the disease to further susceptible scions. The theoretical aspects of the results are discussed, considerations of control and the practical significance of the ‘carrying’ capacity being left for a

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1944.tb06206.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

An experiment is described by which an attempt was made to determine the effect of manurial treatments on the damage caused by the shot‐hole borer of tea. Increases in yields of the plots were accompanied by increases in the damage caused by the beetles as measured by the number of broken branches‐an unusual correlation between pest damage and harvest (r=+0.9267). The experiment failed to indicate clearly the cause of increased damage following manuring, but possibly it results from an increase in the number of galleries formed (r=+0.65

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1944.tb06207.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

A method has been developed, and is here briefly described, by means of which all the wireworm larvae of all stages can be collected from soil samples. By use of that method, complete wireworm populations have been obtained from soil samples of three types, two of which provide large homogeneous populations for detailed study while the third gives information about the seasonal and spatial infestation of fields. These collections show that the wireworm population of English pasture land is on the average about three times as large as has been commonly supposed. Populations have been found ranging up to ten millions per acre in the top 12 in. of soil. In two pastures studied intensively throughout the year, the wireworm population has been found to consist of large numbers of small larvae, decreasing numbers of larger larvae, and comparatively few of the very large larvae that have usually been allowed to represent the population. Such a composition is shown to be characteristic of wireworm populations under old grass at all seasons of the year and in several fields in different parts of the country. This result suggests that in research on the wireworm problem it is desirable to take into consideration the whole wireworm population throughout the year, not merely the large larvae during the cropping season.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1944.tb06208.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY

摘要:

The estimation of dinitro‐o‐cresol in winter washes consisting of petroleum oil, the cresol and emulsifier, must first involve the separation of the cresol from the other constituents present. A method applicable to the cases of emulsions compounded with various types of emulsiner failed when sulphite lye was present, and this was shown to be due to the action on the cresol of reducing sugars in alkaline solution. Avoiding an alkaline extraction until these interfering substances had been effectively removed led to an alternative method by which it was possible to separate D.N.C. in this type of emulsion.The results obtained demonstrate that the methods described are satisfactory for the routine estimation of D.N.C. in petroleum oil/D.N.C. emulsi

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1944.tb06209.x

出版商:Blackwell Publishing Ltd    

年代:1944

数据来源: WILEY