ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1947.tb06353.x

出版商:Blackwell Publishing Ltd    

年代:1947

数据来源: WILEY

摘要:

Various methods of trapping click beetles were tried, the aim being to devise a method which could be used for population and movement studies in grass fields. It is shown that a trap consisting of a 3 in. thickness of hay over closely clipped grass is suitable for this purpose. Annual and daily activity are discussed. Maximum activity occurred in late May and early June, and during the afternoon and evening. The beetles showed a preference for the most humid sites during dry weather. Numbers fell as the hedge was approached and very few occurred under the hedge. Marked beetles were released, and the maximum distance at which they were recovered was 26 yards (23.8 m.). The majority moved in a very restricted area.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1947.tb06354.x

出版商:Blackwell Publishing Ltd    

年代:1947

数据来源: WILEY

摘要:

The scolytid beetle,Xyleborus fornicatusEichoff, which is an important pest of the tea bush in Ceylon, has been reared from egg to adult for the first time in artificial culture with its ambrosial fungusMonacrosporium ambrosium.Deaths in culture were numerous, yet sufficient data on the periods occupied in the different stages were collected to afford an opportunity for testing conclusions derived by the use of less direct methods. Results indicate that temperature materially affects the length of the life cycle and mainly controls the altitudinal distribution of the pest in Ceylon.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1947.tb06355.x

出版商:Blackwell Publishing Ltd    

年代:1947

数据来源: WILEY

摘要:

Sodium arsenite used at a bath strength of 0.2% As2O3is shown to protect sheep to a large extent from infestation for periods of from 1 to 2 weeks. Coal‐tar creosote dips, though usually effective in killing attached ticks, have no protective effect against reinfestation. Derris, either as ground root or as extract, kills all attached ticks at dilutions down to the order of I part extract in 15,000 of water. At a concentration of 1 part in 5000 it has an effective duration comparable to that of arsenic at 0.2% As2O3. Its maximum effective duration, when applied as an emulsion wash, appears to be 14–17 days.The addition of wool grease enhances the effective duration of arsenic, but not of derris. The effect of immersion time is important for both arsenical and derris dips, but is especially important for the latter. For full effect with derris washes sheep must be immersed for at least half a minute.A protective dip is described which markedly lowers the infestation of dipped sheep for about 3 we

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1947.tb06356.x

出版商:Blackwell Publishing Ltd    

年代:1947

数据来源: WILEY

摘要:

Thirty different pretreatments have been tested, in addition to those mentioned in a previous contribution, for their efficiency in prolonging the effective toxic life of a film of pyrethrins in Shell Oil P 31 deposited on brick. Reasons for the success or failure of the various types of pretreatment are considered. Seven substances selected for further trial were tested on four more building materials—limewashed brick, wood, cement, and cement‐sand mixture. The five pretreatments which gave good results on all or most of these substrates were then tested to determine how long they would continue to support a toxic film on cement. Solutions of size and gelatin caused the greatest persistence of toxicity of the pyrethrum films. The flour beetle,Tribolium castaneumHerbst, was used throughout as the test ins

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1947.tb06357.x

出版商:Blackwell Publishing Ltd    

年代:1947

数据来源: WILEY

摘要:

An apparatus and a technique are described for the study of the effect of liquid insecticidal preparations by dipping insects in the toxic material. The method is applicable to quick‐settling suspensions and quick‐creaming emulsions as well as to solutions. Dipping is performed at constant temperature with end‐over‐end shaking; and the technique has the advantage over the other dipping methods that have been described in that handling of individual insects whilst wet is eli

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1947.tb06358.x

出版商:Blackwell Publishing Ltd    

年代:1947

数据来源: WILEY

摘要:

Calcium chloroacetate at 3 and 6 cwt./acre produced significant increases in the yields of sugar beet (both washed beet and total sugar) in a trial on fen soil of the ‘skirt’ type infested with beet eelworm,Heterodera schachtiiSchmidt. However, the material had no effect on the eelworm content of the soil whether measured by cysts, viable cysts or eggs and larvae. An instance is recorded of a significant drop in the level of the beet eelworm infestation in the presence of sugar b

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1947.tb06359.x

出版商:Blackwell Publishing Ltd    

年代:1947

数据来源: WILEY

摘要:

The garden slug,Arion hortensisFér., and the keeled slugs,Milaxspp., are the slugs mainly responsible for primary damage to potato tubers in the south‐west of England. A variety trial clearly demonstrated the existence of significant differences in susceptibility to slug attack between the three varieties tested. Arran Banner was the most damaged variety, Arran Peak the least, while Majestic occupied an intermediate position. Varietal differences in the amount and time of damage to tubers were associated with differences in the dates of maturity, and little damage occurred prior to the maturing of the tuber. The results confirm the need for prompt lifting of the potato crop on maturity, in order to avoid damage by slu

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1947.tb06360.x

出版商:Blackwell Publishing Ltd    

年代:1947

数据来源: WILEY

摘要:

The nature of the competition between barley and the twitch grass,Holcus mollis, has been studied.H. mollishas overrun much of the light, semi‐acid arable land near Woburn on Lower Greensand soils; about 2 1/2 tons of dry rhizomes and roots per acre were dug up on land where it had grown for 10 months. All this rhizome growth occurred within the top 8 in. of the soil.H. molliscommonly increases until the roots occupy from 0.11 to 0.141. root space per 1 g. dried roots and rhizomes. It is slightly superior to barley in ability to utilize available nitrogen.When barley and thisHolcusare grown together with abundance of food and water for both plants, the effect of the weed on the yield of barley depends on whether the barley or the weed first becomes established and on the rate of sowing of the barley. If barley growth begins before that ofHolcus, it may smother the weed completely and sustain no loss of yield provided the barley is planted thickly enough. If the two competing plants start at the same time, thickness of planting is still able to limit the extent to which the weed can reduce the yield of barley, though even with the thickest planting theHolcuscan reduce barley yield by one‐third. WhereHolcusis already established in the ground from the previous year and the crop is thinly planted, the weed is able to eliminate the barley completely, but where barley is sown thickly it is still able to give a 50% yield.With a sparse crop of barley, an increase in the number of weed units makes no difference to the growth of the barley provided the crop becomes well established. Where the crop and the weed start together and so compete on equal terms, any increase ofHolcusgrowth is obtained at the cost of an almost equal falling off in the yield of barley, showing that the respective plant growths are almost complementary. Once the weed has fully occupied the soil, it is able to suppress the growth of the barley almost entirely. The barley and theHolcusreduce the growth of each other even when the root space and supply of plant food are ample for b

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1947.tb06361.x

出版商:Blackwell Publishing Ltd    

年代:1947

数据来源: WILEY

摘要:

Pot experiments at the Gezira Research Farm showed thatStriga hermonthicaBenth. is not confined to the Gramineae but can also parasitize groundnuts, cowpea, dolichos bean and soya bean, causing a loss in yield in all but the last‐named. TheStrigaplants developing on the roots of these hosts were small, apparently ill‐nourished and did not grow more than 1 cm. above the ground, in contrast to the vigorous, floweringStrigaplants that develop on sorghum. The greatest reduction in yield in these experiments was in dolichos bean, where the aerial growth was reduced 60%; no significant reduction in root weight was found in groundnuts, cowpea or soya bean. The last‐named plant appeared to be feebly parasitized byS. hermonthica.A reduction in total nodule weight, but not in number of nodules, was obtained in groundnuts and cowpea. Parasitized dolichos bean showed a reduction in both the number of nodules and in nodule dry weight; in groundnuts, the later fruit production was seriously reduced.The use of these leguminous crops to cleanStriga‐infested soil is di

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1947.tb06362.x

出版商:Blackwell Publishing Ltd    

年代:1947

数据来源: WILEY