摘要:

SUMMARYIn studies on seed transmission ofDidymellastem‐rot of tomatoes in the outdoor crop, heavily infected seed was sown in the glasshouse in January, March and April and the surviving plants were subsequently planted in the field. 50% of the plants grown from the January sowing became infected and a few of them first showed symptoms after planting in the field. On the other hand only 9 and 5%, respectively, of the plants from the other two sowings became infected, none of them after field planting. No infection occurred on plants raised in soil in which infected seeds had previously been sown. Lesions arising from seed‐borne infection occurred on the cotyledons or hypocotyl and could be distinguished by their position on the mature plant from those resulting from other sour

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1962.tb05991.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

SUMMARYBacillus subtilisis capable of producing the antibiotic bulbiformin in soil. Antibiotic production is considerably enhanced when the soil is sterile and enriched with nutrients such as aspartic acid or asparagin, and dextrose or certain root residues. In the presence of the root supplements the antibiotic persists in soil over several weeks in fairly high concentrations.Under favourable conditions for antibiotic production such as the presence of root residues, inoculation ofB. subtilisinto soil results in a marked lowering of the incidence of pigeon‐pea wilt due toFusarium udu

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1962.tb05992.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

SUMMARYThe effect of growing resistant potatoes bred fromSolanum tuberosumsubsp.andigenaand of non‐host crops on a potato‐root eelworm,Heterodera rostochiensis, population was studied for 4 years in microplots of a sandy loam. The reduction in the egg population from growing resistant potatoes was about 80% per year, a higher value than had been obtained previously for a black fen soil but agreeing with Dutch and German results. After 4 years of resistant potatoes the egg population was only about 1% of the initial value, and no increase in the frequency of ‘resistance‐breaking’ (biotype B) eelworms was detectable. Reductions in the egg populations from growing non‐host crops were about 60% in the first year but very much smaller in the second to fourth years. After 4 years of non‐host crops the egg population was still about 25% of the

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1962.tb05993.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

SUMMARY0.025% endrin and 0.05% Rogor (dimethoate), when incorporated in standard metaldehyde and bran slug baits did not increase the catch of slugs. Both insecticides in bran biscuits acted as repellents.The addition of 1 part of 50% Sevin (I‐naphthyl‐N‐methylcarbamate) to 40 parts of the standard metaldehyde and bran mixture improved the catch by 15%.Arion hortensisdid not appear to be attracted to metaldehyde to the same extent asAgriolimax reticulatusandMilax budapestensisand the latter species responded more when the nights were warm.Meteorological observations suggest that in the autumn and winter months more slugs are trapped when the night air temperature and the morning relative humidity are high. The age of the biscuits, the grass minimum temperature and the mean night air temperature accounted for 70% of the variance of the catch of metaldehyde bis

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1962.tb05994.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

SUMMARYThe rates of increase of temperature and of population density are calculated for an insulated culture of granary weevils, assuming a Malthusian rate of increase, and basing heat production on respiration rates. This is done first by a step method, but it is shown that the increase in population density can be related to rise in temperature, irrespective of the original density, which makes a short‐cut method possible.The calculations are then modified for the situation in which the culture is embedded in and loses heat by conduction to a bulk of uninfested grain. The spread of heat by conduction is slow; spread by convection is not considered. At I m. from a hot pocket with a steady heat output, the rise of temperature at equilibrium will be less than half the rise at the margin of the hot pocket and only 15% of this rise will be achieved in 4 weeks. The numbers of insects needed to raise the temperature of an infested pocket in a grain bulk are much larger than those required for an insulated culture. The extra time required to reach a temperature is that needed to build up a sufficient population in the original environmental conditions.It is argued that hot pockets increase in size because of the movement of insects induced by high temperatures and by overcrowding, rather than because of spread of heat by conduction. Convection currents cause upward, but not lateral, extension of hot pockets. If sufficient insects are to develop to produce enough heat to cause high temperatures the expansion of a hot spot is necessary, so that small cages of insects cannot be used to induce heating experimentally.Warehouse observations are described to support these predictions. Heating of home‐produced grain in Britain is caused chiefly through storing either grain which is damp and therefore heats, or dried grain which has been insufficiently cooled. Either produces an ideal environment for any stored‐grain insect species.Stored grain should be inspected both to find insects and to measure its temperature and moisture content. Any warehouse containing grain at temperatures above 22° C. and insects should be examined m

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1962.tb05995.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

SUMMARYAdditional to previously recorded host reactions, Trinidad cowpea mosaic caused local lesions in French bean (Phaseolus vulgarisL.), Bengal bean (Mucuna aterrima, Holland),Petunia hybridaVilm. andChenopodium amaranticolorCoste&Reyn; the last two are the only known non‐leguminous hosts.C. amaranticolorand French bean were used to study some properties of the virus. Infectivity was not affected by exposure to pH values between 5 and 9.1, to a 50% saturated solution of ammonium sulphate or a 50% solution of acetone or ethyl alcohol. The virus has polyhedral particles with a mean diameter of 25 mμ (approx

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1962.tb05996.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

SUMMARY‘Woodiness’ of passion fruit (Passiflora edulisSims.) in Kenya and Australia is considered to be caused by cucumber mosaic virus. A virus from similarly affected vines in Western Nigeria is transmissible by sap inoculation and byAphis gossypiiGlover, as is cucumber mosaic virus and the ‘woodiness’ virus in Kenya and Australia, but its apparent restriction to the genusPassiflora, the shape of its particles and the manner of transmission by aphids suggest that it is a distinct virus for which the name passion fruit mosaic virus is proposed.Chenopodium amaranticolorCoste&Reyn. produces countable local lesions when inoculated with preparations purified and concentrated by heat clarification and high‐speed centrifugation. Salt concentrations that are tolerated by other plant viruses seem to inactivate passion fruit mos

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1962.tb05997.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

摘要:

SUMMARYA virus first found in tobacco in Rhodesia in 1958 was widespread in 1959, usually together with other viruses. It is readily transmitted by mechanical inoculation.Myzus persicaetransmitted it from plants that were also infected with another virus, probably tobacco vein‐distorting virus, but not from plants infected with it alone. The aphids became increasingly likely to transmit as their feeding time on infected plants increased up to 24 hr.; after virus‐acquisition feeding times of 24–48 hr. they remained infectious for several days. The virus, named tobacco bushy‐top because of the characteristic way it stimulates the growth of axillary shoots, resembles tobacco mottle virus in many respects, and as tobacco mottle virus partially protects plants against bushy‐top virus they may be relate

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1962.tb05998.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1962.tb05999.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1962.tb06000.x

出版商:Blackwell Publishing Ltd    

年代:1962

数据来源: WILEY