摘要:

SUMMARYOf the list of possible remedies the following are the least desirable for using on a large scale for the reasons stated.Nicotine Uncertain in its action and being poisonous must be used cautiously.Pyridine Highly offensive odour.Petroleum Inflammable. Bugs dislike it, they often leave the pots and under certain conditions they may escape death.Methyl alcohol Inflammable, action slow.Acetone Will not mix with water—injections into the soil are impracticable.Fuel oil Bugs escape from the pots.Miscible fusel oil No effect.The three following stand out as being the most effective and suitable:Tetrachlorethane (Westoran)Trichlorethylene (Westropol)Potassium sulpho‐carbonateThe root mealy bug and root aphis living under similar conditions in pots, adopting similar methods of feeding and protection, respond similarly to any particular treatment. The grower may, therefore, cope with both pests by the application of a common rem

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04292.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04293.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04294.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

摘要:

SUMMARY1Increased nitrogen fixation byAzotobacter chroococcumin the presence of protozoa, as shown by Nasir, has been confirmed2The same effect is found, using soil as a medium.3There is a definite relationship between the efficiency of the strain used, the incubation period and the concentration of mannitol employed.4The feeding action ofColpidium colpodaandHartmanella hydlinaonAzotobacterhas been demonstrated.5The reason for increased nitrogen fixation appears to be due to the efficiency ofAzotobacterbeing maintained for a longer period.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04295.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

摘要:

SUMMARY1The effect of the parent crop husbandry in the case of oats has been traced upon the seed, its germination and early growth and yield.2The beneficial effects of seed grading by weight are again emphasised, but it has been demonstrated that such mass selection does not cause an improvement of the seed qualities in every respect. More subtle characteristics than weight have a predetermining effect.3The relationship between environmental conditions and panicle characters has been discussed.4In spring oats grown under Welsh conditions the importance of establishment, which can be roughly gauged by laboratory tests, is emphasised. Heating the seed samples appears to be a suitable method by which further information can be obtained as to the seed's vigour.5It seems that an index to yield is likely to be found in this direction. Seed vigour is correlated with yield.6Plant to plant variation is so wide between spaced individuals that little indication of the graminaceous plant's capabilities were discernible in seedling behaviour.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04296.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

摘要:

SUMMARY1The rate of germination of tomato seeds is practically unaffected when the seed boxes are exposed to atmospheres enriched with carbon dioxide.2Increases of over 20 per cent, in marketable tomato crops result when the plants are subjected to atmospheres containing 0.6 per cent, of CO2for 1 or 2 hours daily.3Cucumbers heated with atmospheres containing 0.9 per cent. CO2for 1 hour daily showed an increase in crop of 16 per cent.4In the case of the 1925 tomato crop, and to a less degree of the 1924 crop, a considerable part of the increased picking is manifested in June, when market prices are high.5In its effect on the crop carbon dioxide generated slowly at the soil surface is not as beneficial as the gas when generated quickly and mixed with the air surrounding the plants.6Plants grown in houses which have been used for carbon dioxide experiments show an increased susceptibility to infection byColletotrichum atramentarium.7When carbon dioxide is generated quickly in a house an appreciable loss of this gas always occurs. This loss appears to be independent of temperature and varies directly with the amount of ventilation.8Experiments with apparatus devised for the use of carbon dioxide on a commercial scale were unsuccessful owing to the inadequacy of the apparatus.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04297.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04298.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

摘要:

SUMMARYThe difficulty of reconciling various cultures of the scab organism with any one defined type ofA. scabies(Thaxter) Güssow is discussed.Inclusion of all such cultures into oneA. scabiesgroup has no justification.A technique has been evolved whereby the cultural characters ofActinomycesmay be maintained in sub‐culture.Twenty‐fourActinomycesstrains were isolated from potato scabs and other sources, and the cultural and morphological characters of these have been worked out and described.Three pairs of duplicate strains appeared, but with these exceptions, the differences between the strains were of specific rank.One of the species appears to be identical with Thaxter's original scab organism and is thus referred toA. scabies(Thaxter) Güssow; the remainder are new and have accordingly been named.Eleven of the species were found to produce scab on potatoes.The various type a of common scab have been defined, and it has been shown that type of scab is dependent on the infectingActinomycesspecies. The variety of potato may modify but cannot materially change this type.A. scabies(Thaxter) Güssow (emend. M. and B.) produced a deeply furrowed scab apparently identical with the “Deep Scab” described by Thaxter. This species was also found to attack the roots and stolons of potato plants.The occurrence of scab in virgin soils and the predominance of certain scab types in certain soils and in different years are

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04299.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1926.tb04300.x

出版商:Blackwell Publishing Ltd    

年代:1926

数据来源: WILEY