ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1949.tb06926.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

Tomato aucuba mosaic virus, tobacco mosaic virus and potato virus X took 3'5‐4, 5 and 3 days respectively to move from inoculated tomato leaflets into the petioles and stemsOn reaching the stem each virus usually first moved downward, but in some plants both upward and downward movement occurred simultaneously and in a fewupward movement occurred first.All three viruses travelled through the stem at approximately the same rate. Each was capable of travelling more than 80 cm. during the first 12 hr. after entering the stem, giving a minimal average rate of about 8 cm. per hr.Uninfected pieces of stem invariably occurred between infected pieces. Maximum lengths of stem through which virus particles had apparently passed without causing infection, were 44.5, 49 and 39 cm. for the three viruse

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1949.tb06927.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

‘Aspermy’ is suggested for the name of a virus disease of tomato apparently distinct from any previously described. The virus was transmitted byMyzus persicaefrom infected to healthy tobacco plants, but not from or to other hosts. Some properties of the virus are described together with the symptoms it causes in various ho

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1949.tb06928.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

A mosaic of cowpea and asparagus‐bean (Vigna unguiculata)is common in Trinidad. The same virus sometimes attacksCajanus indicus, Crotalaria juncea, Glycine max, Phaseolus mungoandP. aureus, usually when growing near to infected cowpeas.Desmodium frutescens, Psophocarpus tetragonolobus, Sesbania speciosa, Vigna vexillata, Phaseolus trinerviusand varieties ofP. Iunatusare also susceptible to systemic infection. Most of the above give local lesions, which are the only symptoms produced onCanavalia ensiformisandDolichos lablab.No infections were obtained onPhaseolus vulgaris, or on any plant outside the Leguminoseae.The virus is seed‐borne in asparagus‐bean, but apparently not in tested cowpea varieties. The leaf beetleCeratoma ruficornisis a vector, and is probably largely responsible for spread in the field;Aphis medicaginisseems unable to transmit the disease. The thermal inactivation‐point of the virus is 66°C., its dilution end‐point 1: 100,000, and longevityin vitroov

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1949.tb06929.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

The aphidMyzus persicaeSulz. overwintered successfully on an almond‐peach hybrid for three consecutive years. Experiments provided no evidence in favour of the theory that the olfactory sense is used by aphids to find their host, nor were flying aphids attracted to otherM. persicaeor to honeydew on the host. Having found their host, presumably by chance, alate gynoparae tended to associate in group

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1949.tb06930.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

Surveys of winter wheat from 1939 to 1946 show that eyespot(Cercosporella herpotrichoidesFron.) occurs throughout Britain and that its incidence depends largely on previous cropping and on weather. Examination of 551 crops on land whose cropping for the previous 4 years was known showed that the incidence rose steadily with increasing numbers of preceding wheat and barley crops: where neither crop had been taken for 4 years the proportion of crops with more than 70% infected straws was 2%, rising to 45% where three or four such crops had been taken and the average straws infected rose from 6 to 55%.The percentage infection to be expected in various groups of crops was calculated from previous cropping; it was compared with the actual infection and so used to assess the importance of other factors in determining the incidence of eyespot. High spring rainfall, early sowing and a dense plant increased incidence and low spring rainfall, late sowing and a thin plant reduced it.Eyespot was not usually severe on newly ploughed grassland until the third or fourth crop of wheat, but under very wet conditions it was sometimes severe in the second crop.Oats is much less susceptible than wheat or barley, but some crops were found with a third of their straws infected.A brief survey of winter wheat in Holland suggested possible causes for the rise and fall of eyespot in recent years and for its present lower incidence there as compared with East Anglia.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1949.tb06931.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

Leaves of five weed species(Brassica sinapis, Cirsium arvense, Polygonum aviculare, P. convolvulusandPotentilla reptans)from fertilizer trials on barley at four sites in Hampshire were analysed with a view to using their composition in forecasting the response of barley to fertilizers. The samples were gathered from as many of the 108 plots as possible, and were analysed spectrographically for calcium, iron, magnesium, manganese, potassium and sodium.Marked differences in composition between the five species were recorded, the most noteworthy being the high sodium content ofBrassica sinapisandCirsium arvenseand the high manganese content ofPotentilla reptans.There were also marked differences between the four sites, but these were not uniform as between the different species, and often failed to agree with those observed for barley.Superphosphate applications decreased the manganese content of the weeds in many cases, and increased their calcium content. Muriate of potash increased their potassium content, but tended to decrease that of magnesium and sodium. The only general effect of sulphate of ammonia on the composition of the weeds was a decrease in iron content.Except inCirsium arvense, the potassium content of weed leaves was correlated with that of barley on the same plot if differences within a site only were considered. Differences between sites were not correlated in this way. The correlation between potassium content of weed leaves and the response of barley to muriate of potash application was worthy of note only inPolygonum convolvulus, and even in this case the correlation of site differences did not reach significance. It is tentatively suggested that increases in the grain yield of barley as a result of muriate of potash application are likely to occur only where the leaves of P.convolvuluscontain less than 1.83% potassium.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1949.tb06932.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

A D‐D mixture has been tested againstHeterodera rostochiensisat seven 2‐acre sites on sands, silts and blackland soils. Apart from a pilot trial where soil was injected in spring, injections were carried out in the autumn, and potatoes were grown the following year. Factors investigated were rate of application (0, 200, 400 and 800 lb. D‐D/acre), depth of injection (4 or 8 in.) and the effect of rolling after injection. At the most responsive of the sites (Wainfleet), increases in yield, kill, and the post‐crop eelworm population were all roughly proportional to the rate of application. Under favourable circumstances a 50% increase in yield and something like a 50% reduction in eelworm population 4 weeks after injection can be expected from 800 lb./acre, but the reduction is more than made good during the growth of the subsequent crop; accelerated multiplication of eelworm on the treated plots leads to their having a larger population than the untreated controls at lifting time. Of the sites tested, the blackland soils gave a lower eelworm kill and a much lower yield increase from D‐D than silts or sands. After autumn injection the nematocidal, and probably the phytocidal, effects of D‐D persist in the soil for many weeks. The hypochlorite method of ‘hatching’ eelworm larvae for counting has pr

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1949.tb06933.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

A new sprayer is described which was designed in 1945 for the control of adult flies and mosquitoes with insecticides having a kerosene base. This sprayer has been shown in laboratory tests against houseflies,Musca domesticaL., and yellow fever mosquitoes,Aedes aegyptiL., to be highly efficient for both kill and knockdown and to achieve a particularly rapid knock‐down of mosquitoes.The sprayer can be operated with a hand pump or connected to a supply of compressed air. Air consumption is very low and when the sprayer is power‐operated, optimum biological efficiency is obtained at 20 lb./sq.in. air pressure. There is no spitting or dribbling from the nozzle and the mist does not settle so rapidly as to cause any appreciable staining of the floor. Although robust it is light, easily manipulated and can be dismantled into component parts for cleaning. It has no adjustments; but the nozzle, which must be machined with precision, is automatically set in its most effective spraying position when screwed home tigh

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1949.tb06934.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY

摘要:

(With Plate 7 and 5 Text‐figures) Following a discussion of methods for the uniform application of insecticides for evaluation purposes, a description of a vertical spraying apparatus is given. The spraying procedure is described. By varying different factors and estimating the consequent variation in the replication of deposit the accuracy of the apparatus was determined. The main advantage of the present method lies in the possibility of accurate and quick readjustment of the nozzle by means of a calibrated adjusting nut and a fixed vertical pointer. The nozzle is constructed of stainless metals and is not easily damage

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1949.tb06935.x

出版商:Blackwell Publishing Ltd    

年代:1949

数据来源: WILEY