摘要:

SUMMARY.11.Sitona hispidulais common throughout Great Britain upon clover and lucerne.2The adults eat the leaves and the larvae damage the roots.3Sitona sulcifronsis frequently abundant upon “seeds” clover and the larvae feed upon the root nodules.4Sitona crinilafrequents tares, clover, lucerne, etc., but is rarely sufficiently common to cause injury.5The adults ofS. hispidulaare either fully‐winged or brachypterous and two forms of brachypterous wings have been observed inS. sulcifrons.6The life‐history of these three species has been investigated in Britain for the first time.7There is only one generation in the year.8The adults live 12 months.9The period of oviposition and the length of the egg, larval and pupal stages varies according to the species.10The BraconidsPerilitus rutilusNees,P. cerealiumHal.,P. aethiopsNees,Pygostolus falcalusNees and a species ofLiophronare recorded for the first time as parasites of the adult beetles.11The fungusBotrytis bassiana(Balsamo) Montagne attacks these species o

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1922.tb05941.x

出版商:Blackwell Publishing Ltd    

年代:1922

数据来源: WILEY

摘要:

SUMMARY.11. “Sleepy Disease” or “Wilt” of tomatoes may Joe caused by one of two fungi,Fusarium lycopersiciorVerticittium albo‐atrum.2Massee's “diplocladium stage” ofF. lycopersicihas been shown to beV. albo‐atrum.3The wilt producing fungi attack the roots and grow up through the vascular bundles into the stem, leaves and sometimes the fruits. The wood of a diseased plant is a light or dark brown colour.4The average temperature is a “limiting factor” in determining which fungus is active.F. lycoperstcigrows best at an average temperature of 27‐8‐28‐9oC. If the temperature remains constantly much below this, little infection results.V. albo‐atrumdevelops well at temperatures from 15‐6‐24‐0oC, being most active at 2M‐22‐8oC. Above an average temperature of 25oC. little infection occurs.5The average temperature conditions existing in glasshouses in this country are generally too low forF. lycopersiciand consequently it is rarely found as a cause of tomato wilt. The relatively low temperatures are favourable toV. albo‐atrum,which accordingly is the most important cause of wilt.6Wilted plants soon die under conditions of low temperature, but if the average temperature be raised above 25oC, they recover and will bear a crop so long as the high temperature is maintained. When the temperature again drops, wilt reappears and death results.7V. albo‐atrumfrom tomato readily induces wilt in the potato, eggplant, snapdragon, cotton, pepper plant and cucumber, and produces a stunted condition of the sycamore and elm.8A number of different strains ofV. albo‐atrumhave been isolated which vary in their rate of growth, the amount and rate of production of microsclerotia, and in colour production; but no evidence has been obtained^to show that there may be different strains restricted to different varieties of tomatoes.9In pure culture the fungus has been shown to produce a large number of enzymes and there are strong indications that substances of a toxic nature play an important part in producing wilt.10There is a distinct relation between hardness of growth and susceptibility to wilt; the harder growing varieties and plants suffering from starvation or a severe check in the young stages being most susceptible to attack. Most varieties of tomatoes cultivated in this country are susceptible toVertidllium,but Manx Marvel has proved to be practically immune and Bides' Recruit highly resistant.11Certain cultural devices, including regulation of the temperature and shade, have been devised which assist “wilted plants” to recover.12Further investigations upon soil sterilisation and the pr

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1922.tb05942.x

出版商:Blackwell Publishing Ltd    

年代:1922

数据来源: WILEY

摘要:

SUMMARY.The reproduction ofAphis rumiciswas tested on 18 varieties of field beans and the results compared with the reproduction on Prolific Longpod broad beans.The aphids used in the experiments were the offspring from one Fundatrix.The experiments were all carried out under similar conditions. Five plants of each variety were tested, and the total number of aphids produced on each plant, from one a. v. ♀, in 14 days was counted.The mean values of infestation for the varieties range from 37 to 1037,videTables I and II.These mean values allow of the varieties being grouped into classes representing various grades of susceptibility, ranging from 98 per cent. to 3 per cent,videTable III.Vicia narbonensishas a very low susceptibility. The results obtained indicate that resistance or susceptibility may be largely determined by genetic factors in the plan

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1922.tb05943.x

出版商:Blackwell Publishing Ltd    

年代:1922

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1922.tb05944.x

出版商:Blackwell Publishing Ltd    

年代:1922

数据来源: WILEY

摘要:

Summary.11. There is clear evidence in the literature that the toxic action of traces of illuminating gas upon plants may be traced to the presence of gaseous unsaturated hydrocarbons. A concentration of one part of ethylene in ten million of air is toxic to the etiolated epicotyl of a pea.2The effect of these unsaturated hydrocarbons can be traced in the case of root or etiolated stem to their inhibition of the formation of a functional primary endodermis, which is usually present in these plant structures.3The unsaturated hydrocarbons prevent the formation of a functional endodermis, by preventing the normal accumulations of unsaturated acids in the region of the future Casparian strip.4It is suggested that the effect of traces of these gaseous unsaturated hydrocarbons upon cork formation may be due to the arrest of the normal deposit of fatty acids in the membranes of the cork cells.5The practical significance of this work lies in the fact that definite diagnostic features may now be sought for when injuries to plants are suspected to be due to gas poisoning.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1922.tb05945.x

出版商:Blackwell Publishing Ltd    

年代:1922

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1922.tb05946.x

出版商:Blackwell Publishing Ltd    

年代:1922

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1922.tb05947.x

出版商:Blackwell Publishing Ltd    

年代:1922

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1922.tb05948.x

出版商:Blackwell Publishing Ltd    

年代:1922

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1922.tb05949.x

出版商:Blackwell Publishing Ltd    

年代:1922

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1922.tb05950.x

出版商:Blackwell Publishing Ltd    

年代:1922

数据来源: WILEY