摘要:

SUMMARYA derivative, prepared from the aphid alarm pheromone (E)‐β‐farnesene and the saturated straight 14‐carbon chain dialkyl ester of acetylene dicarboxylic acid, was the most active compound tested for inhibiting acquisition by the aphid Myzus persicae of the non‐persistently transmitted potato virus Y (PVY). Derivatives lacking, or with shorter, or branched or partially‐unsaturated carbon side‐chains were less active. The one derivative tested also inhibited inoculation of PVY, and acquisition of beet mosaic virus (also non‐persistent) and the semi‐persistent beet yellows virus. However, it had no obvious effect on aphid probing behaviour; related compounds lacking the (E)‐β‐farnesene moiety also inhibit

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb05604.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYNon‐decay fungi and bacteria which had been isolated from pruning wounds of beech (Fagus sylvatica) were examined for their ability to check the growth of decay fungi in a number of laboratory tests. Several fungi and bacteria inhibited growth although the degree of inhibition varied to some extent with the test. The most consistently antagonistic fungi were Trichoderma spp., especially an isolate of T. viride. The most antagonistic bacteria were Bacillus sp

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb05605.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYIn an attempt to control fungi causing decay a range of micro‐organisms, selected after laboratory tests, was inoculated into wounds made in the trunks of beech trees. The most successful micro‐organism was an isolate of Trichodermaviride, which, over a period of 4 years, maintained significantly lower colonisation by decay fungi at both sites ‐ c. 15% of the level found in uninoculated wounds. T.viridecould be reisolated from the majority of wounds into which it had been inoculated up to 4 years later. No other antagonist persisted very effectively. Inoculation of T.viridein glycerol improved its establishment but malt extract and sucrose had no such effect. Both the addition of glycerol to wounds and the wrapping of them in black PVC sheet increased natural colonisation by T.viride. The use of PVC but not glycerol reduced numbers of decay fungi but not through the agency of T.viridepresent by natural infection, as this proved generally ineffective in the control of decay fungi. Another isolate of T.viridepersisted considerably better when covered with a wound se

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb05606.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYEyespot stem lesions, mildew and leaf spots caused by Drechslera spp. and a Spermospora sp. were identified in perennial ryegrass seed production trials in 1981 and 1982, but their incidence was low, and only rarely was more than 10% of any particular leaf area lesioned at any time during the growing season. Fungicide application (triadimefon plus carbendazim plus captafol) at monthly intervals from tillering (February) until harvest (July) increased seed yield by 15% in 1981 and 43% in 1982, mainly through an increase in the number of seeds per spikelet. Seed yield increases were related to an increased leaf area duration, brought about by delays in senescence of photosynthetic tissue, rather than pathogenic effects. Reasons for this yield response to fungicide application in the virtual absence of pathogens are discussed.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb05607.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYIn soil inoculated with Pythium ultimum or Pythium irregulare, seed treatment with either Apron 70 (=1 g metalaxyl and 1 g captan/kg seed) or thiram gave control of pre‐emergence damping‐off of Brussels sprout and cabbage seedlings. On cauliflower, Apron 70 was significantly more effective than thiram. No post‐emergence damping‐off occurred in either of these crops or in oil‐seed rape following seed treatment with Apron 70 whilst post‐emergence losses from untreated seed ranged from 10·2–19·4% and from thiram treated seed from 5·7‐7·4%. Apron 70 gave complete control ofPeronospora parasiticaon cauliflower inoculated 10 days after sowing; thiram was ineffective. Following seed treatment with Apron 70, metalaxyl was detected in the cotyledons, true leaves and roots of cabbage seedlings up

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb05608.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYPatterns of spread of two aphid borne viruses, the non‐persistently transmitted bean yellow mosaic virus (BYMV) and the persistently transmitted subterranean clover red leaf virus (SCRLV), were compared simultaneously in field plots ofVicia fabaminor grown in a Mediterranean climate (winter‐spring growing season, and dry summer).Spread from a primary source was mapped following the artificial introduction of virus alone, or virus with vector, at the centre of the plots. BYMV spread rapidly from the virus source whether or not vectors were introduced with the virus. By contrast, SCRLV spread from the source only when plants were also artificially infested with the vectorAulacorthum solani.An attempt was made to evaluate the importance of secondary spread of both viruses by assessing the degree of clumping of infected plants that occurred outside the primary sites of virus introduction. BYMV‐infected plants were clumped in each treatment irrespective of whether the virus was introduced alone or with vector, as well as in control plots. Clumping of SCRLV occurred only when the vectors were introduced on virus source plants at the beginning of the experiment.Times of spread were determined both by exposing trap plants at 4‐weekly intervals throughout the 30 month trial period, and by analysing the rates of spread in experimental plots between June and November in one growing season. Both viruses spread in the spring when vectors were flying, but negligible spread of the viruses was observed in the autumn despite aphid flight activity.Times of flight of the four main aphid vector species were continuously monitored with yellow water traps. A major spring and a minor autumn flight peak were observed forAphis craccivora, Macrosiphum euphorbiae, Aulacorthum solaniandMyzus persicae.Aphid flights occurred predominantly in weeks when the mean temperature was in the range 13–17°C. Rainfall above 7 mm per week appeared to affect flights only when mean weekly temperatures were outside the ran

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb05609.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYThe Nigerian National Horticultural Research Institute experimental and commercial farm has a long history of okra mosaic virus (OMV) disease. In an attempt to determine possible sources of inoculum, weeds growing within or around the vicinity of the farm were investigated. Several weeds showed virus or virus‐like disease symptoms and mechanical inoculation of crude sap from three malvaceous weeds(Abutilon hirtum, Sida acuta, andMalvastrum coromandelianum)and one solanaceous weed(Physalis angulata)induced symptoms of OMV on okra test seedlings; serological tests confirmed the presence of OMV. Beetle vectors caught both from weeds and from okra were infective when confined on healthy okra seedlings for 48 h. Increase in the abundance of beetle vectors was accompanied by an increase in the incidence of OMV disease. The implications of these findings in the epidemiology and control of OMV are discusse

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb05610.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYEnzyme‐linked immunosorbent assay (ELISA) was used to test plum trees for prune dwarf (PDV), Prunus necrotic ringspot (NRSV) and apple mosaic (ApMV) viruses, cherry trees for PDV and NRSV, and apple trees for ApMV. Optimum conditions were determined for sampling in large‐scale surveys for these viruses. All three viruses were detected throughout the growing season in individual samples of young leaves, or twigs with newly formed buds. However, when single infected leaves were combined with different numbers of healthy leaves, tests were most successful for all three viruses early in the growing season. PDV was detected in 1/40 (infected/total leaves) cherry leaves in April and May and 1/40 plum leaves until July, whereas NRSV was detected in 1/20 cherry leaves until July and 1/20 plum leaves until May. ApMV was detected in 1/20 apple or plum leaves until June but was detected less readily in mature leaves after June than either NRSV or PDV. There was no evidence of uneven distribution of virus infection in the trees. The viruses were detected in leaf samples kept for 8 wk at 3°C but freezing was less reliable for storage especially with ApMV. ApMV was detected in tests on plants held for several weeks at 25°C, and PDV and NRSV in plants held at

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb05611.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYPlots in a field infested withGlobodera rostochiensisandVerticillium dahliaewere treated in 1971 with methyl bromide, dazomet, aldicarb, benomyl or aldicarb + benomyl and potatoes (cv. Pentland Dell) were grown in four consecutive years. In 1971, all treatments delayed the development of haulm symptoms, decreased soil populations ofG. rostochiensisand increased yields. In the second year yields were increased by all treatments except dazomet whereas in the third and fourth years only benomyl or aldicarb + benomyl increased yields. Soil populations ofV. dahliaewere decreased by methyl bromide in 1971 but not by other treatments or in later years.In 1976, Pentland Dell and Pentland Crown were grown on an infested field in plots fumigated with methyl bromide. Fumigation slightly delayed shoot emergence but increased plant height, ground cover and the size and persistence of the leaves; development of haulm symptoms was delayed and yield increased. Fumigating with methyl bromide at five times the normal rate was more beneficial to Pentland Dell than to Pentland Crown.In a comparison of 10 cultivars in 1975, symptoms developed sooner and yields were smaller on a field infested withG. rostochiensisandV. dahliaethan on a non‐infested field and on both sites Maris Peer plants died soonest and yielded least. Pentland Crown yielded most on the non‐infested field and Maris Piper on the infested fi

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb05612.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYAssociations between different species of nematodes and stem‐boring larvae were studied over two years.Howardula oscinellaewas rarely found in stem‐boring larvae. Usually mermithids were also uncommon, but in one Italian ryegrass(Lolium multiforum)variety trial over 12.5% of stem‐boring larvae were attacked, with different levels of parasitism in larvae from the different ryegrass varieties.Panagrolaimus rigidusnematodes were also identified from stem‐boring larvae andOscinella fritlarvae were the most common host. Greater infestation levels ofP. rigiduswere found in larvae from grazed swards than from cut swards.P. rigidusmay cause the death of some stem‐bori

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb05613.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY