摘要:

SUMMARYChanges in the distribution of adult cabbage root flies were determined in 0–05‐0‐4 ha brassica plots during 1970 and 1971 using yellow water‐traps.The three generations of flies occurred at similar times in both years and the numbers caught generally decreased from the first to the third generation. In resident populations, the numbers of males and females declined by 70 and 40% respectively, between the second and third generations. When there was no decline, immigration presumably compensated for flies trapped or otherwise lost. The results confirmed that male cabbage root fly movement is trivial, that wind has little effect on distribution at a brassica plot and that females move into the crop independently of males. They failed to confirm that females aggregate markedly at hedgerows or fences, that they spend little time in the crop or that they regularly return to hedgerows.Differences in the dispersal behaviour of the male and female flies were reflected in the numbers caught. Some males dispersed actively during the first 2 weeks after emergence but many were displaced slowly downwind. Once at a plot, wind appeared to have little effect on distribution of young males, but older males tended to shelter just downwind of the hedge. Relatively few males were caught near hedges but they tended to aggregate along the crop‐interfaces, particularly during the first generation. Plot size did not appear to influence the pattern of fly distribution greatly. Females dispersed more actively than males and were generally more uniformly distributed through the crops even during periods of immigration. Gravid females entered an isolated plot without accompanying males, inferring that they are migratory and mate near the site of emergence. Female distribution was not related to the stage of ovarial development except during maximum oviposition when those that had laid some eggs visited the hedgerow. Aged females became progressively easier to capture and usually died in

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb01331.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYA virus obtained from pelargonium cvs Irene and Paul Crampel appears to differ from any previously reported; although symptomless in most pelargonium cvs tested, it caused colour break in the flowers of two seedling clones. It seems uncommon in pelargoniums. The virus was readily transmitted by inoculation of sap, but not byMyzus persicaewith short feeds, by dodder or through seed. It infected only fifteen of 100 species tested in six of thirty‐five plant families. Pelargoniums were freed from the virus by heat‐treatment.The virus remained infective after 10 min at 85oC, 3 wk at 20oC or 27 wk at 2oC; it was infective at 1/500000 dilution ofNicotiana clevelandiiorChenopodium quinoasap.Purified preparations were readily made by several methods, and contained isometric particlesc.30 nm diameter. Although a good antigen, the virus was serologically unrelated to any of forty‐two isometric viruses. In immunoelectrophoresis, the virus moved as a single antigenic component towards the cathode. It gave a single, specific zone in density‐gradient centrifugation, and one moving component (s020 w= 125S) in analytical centrifugation. The virus contained one protein of mol. wt.c.41000. The present cryptogram of the virus is (R)/*: */*:S/S:S/*, and the name pelargonium flower‐break virus is

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb01332.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYIn glasshouse tests, trifluralin, when mixed with the soil before sowing, lowered the incidence of clubroot on cabbages.An emulsifiable concentrate was more effective than a wettable powder and control was better in soil alone than in a soil/peat mixture. Four other dinitroaniline herbicides were tested; benfluralin and isopropalin lowered clubroot incidence at non‐phytotoxic rates whereas nitralin and dinitramine did no

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb01333.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYIn glasshouse experiments at Auchincruive, drench applications of benomyl (100 or 142 mg per plant) to the soil surface around the stem bases of pot‐grown tomato plants before inoculation withFusarium oxysporumf.sp.lycopersicireduced the penetration of the fungus up the stems and/or decreased the development of vascular discoloration and associated severity of wilting. Similar drenches applied after establishment of the fungus in the stems either halted or considerably retarded the growth of the pathogen up the vessels. This again was reflected in reduced vascular discoloration and wilt symptoms.In experiments with benomyl over 2 years at a commercial holding in Argyll, the application of soil drenches (at the rates above) shortly after planting out and again 5 weeks later, coupled with a programme of stem and foliar sprays (at 0–05 % a.i.) during the summer, reduced the development of stem lesions caused chiefly byBotrytis cinereaand increased the general survival of plants more than did drench or spray treatments alone. There were indications that ‘ghost spotting’ of the fruit, particularly where spray applications were made, was also slightly reduced, but the magnitude of the effect was not con

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb01334.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYBenomyl, thiabendazole and thiophanate‐methyl were found to be fungistatic againstVerticillium dahliae in vitro.All materials suppressed wilt symptoms on artificially inoculated strawberry plants when applied as a root dip, soil drench or a foliar application.Quantitative bioassays of the amount of toxic residues and fungal colonization in tissues of treated plants after root treatment revealed that these materials or their toxic breakdown products were readily translocated to crown and leaves: they suppressed the internal spread of the pathogen throughout the plant. After foliar application there was no marked basipetal movement of material within the plant: fungal colonization was greatly reduced in treated leaves, but the roots and crowns were colonized to a similar extent to those of untreated plant

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb01335.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYThe direct and systemic antifungal activity of 100 compounds structurally related to iV‐(2, 2, 2‐trichloro‐i‐methoxyethyl)formamide has been measured. Some of the compounds showed either protectant or systemic activity against powdery mildew fungi. Compounds not possessing a terminal formamido group showed little anti‐mildew activity and for good systemic activity an alkyloxy or alkylamino side‐chain in the molecule appeared to b

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb01336.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYFemaleEncarsia formosawere enclosed in artificial arenas containing twenty‐fiveTrialeurodes vaporariorumscales on a Cellophane substrate. Either the substrate or the scales were previously treated with chemicals. The number of oviposition wound marks on the scales was used as a measure of effect on parasite behaviour. The insecticides, tetradifon and γ‐BHC, had their greatest effect when applied to scales. The fungicides, benomyl and dichlofluanid, were more active on the Cellophane. Pirimicarb applied to the scales decreased oviposition, but greatly increased it when applied to the substrate. It is concluded that even sublethal amounts of pesticides may seriously impair the effectiveness of this parasite in commercial biological con

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb01337.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYIn two experiments, foliar sprays of either chlormequat chloride or aminozide depressed top growth, increased root yield and enhanced leaf and root colour in six carrot cultivars. In the first experiment, a direct correlation between concentration of the two retardants and root yield was apparent within the range 0–2000 mg/1 a.i. applied as run‐off sprays to two cultivars. In the second experiment, increases in total root and canning‐size yield and root/shoot ratio were obtained with four cultivars, but the magnitude of these effects was dependent on the time at which the retardants were applied and the time of harvest of the crop. The effects of aminozide on root yield were less persistent than those of chlormequat chloride, the yield differences between untreated and aminozide‐treated plots decreasing with time after appl

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb01338.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYWheat coleoptile sections were treated with a range of auxins and with compounds of related chemical structure which do not exhibit auxin properties. Methods used for measuring the rates of elongation and ethylene evolution of these sections are described.Ethylene was evolved some time after elongation in all cases and increased ethylene production occurred only with compounds showing auxin activity. The results indicate that ethylene evolution was related exponentially to growth.Simultaneous applications of mannitol and 2, 4‐dichloro‐phenoxyacetic acid (2, 4‐D) to wheat sections markedly reduced ethylene evolution compared with the 2, 4‐D controls, even though the level of 2, 4‐D in the tissue apparently remained unchanged.Ethylene significantly inhibited the elongation of wheat coleoptile sections, and it is suggested that ethylene is a natural plant growth inhibitor which becomes mobilised to limit excessi

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb01339.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

SUMMARYPotato seed tubers cv. Maris Peer obtained from a number of sources in England and Scotland were graded into a range of weights and after storage for approximately 3 or 7 months in 1971 or 3 months in 1972 they were planted to determine the effect of seed source on early foliage growth.In both years there were large differences between seed sources on the effect of seed tuber weight on the dry weight of foliage produced in a glasshouse from seed stored for 3 months. In some instances small seed from one source produced the same weight of foliage as large seed from another source. In 1971 after seed storage for 7 months there was no effect of source on foliage dry weight produced in the field. There was, however, no consistent effect of the site of production of the parent seed, of fertilizer treatments of the seed crop, or of N content of the seed tubers. Seed tuber N content increased, though not proportionally, with an increase in seed weight. It was unaffected by source except for seed tubers from one site m 1972.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1973.tb01340.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY