摘要:

SummaryThe effect of constant and alternating temperatures on the life‐history of Diglyphus isaea, as an ectoparasitoid of Liriomyza leafminers on tomato plants, was examined in the laboratory.Parasitoid development and size were significantly affected by temperature and sex. Males showed a shorter development time and pupal size than female parasitoids. Both development time and pupil size in D. isaea differed according to the host species. Pupal size showed no consistent relationship with temperature. The lower thermal threshold for development and oviposition was determined. Fecundity with L. byroniae as host did not differ significantly between temperature regimes. Furthermore, larger females did not produce larger numbers of offspring. Development and reproduction under the alternating temperature regime did not differ from those at the comparable constant temperature, suggesting a rapid response to changes in temperature.The intrinsic rate of increase (rm) and net reproduction (Ro) of D. isaea nearly doubled from 15°C to 25°C and 20°C, respectively, and generation time at 25°C was less than half that at 15°C. Because the parasitoid's population growth is higher than that of these pest insects at all temperatures, D. isaea is a promising candidate for seasonal inoculative biological control of Liriomyza on tomato crops in Scandinavian and western European glasshouses. Possible constraints to its effectiveness are dis

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1989.tb06558.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryFour species of aphid infest wild and cultivated blackberry (Rubus fruticosus agg., R. lachiatus, etc) and other Rubus species in Britain and Continental Europe, ‐ Sitobion fragariae (Walker), Macrosiphum funestum (Macchiati), Amphorophora rubi (Kaltenbach) and Aphis ruborurn (Bösrner). The nymphs, especially the early instars, of the first three species are fairly difficult to differentiate morphologically. However, they can clearly be separated using electrophoresis. The present paper describes diagnostic enzyme/isoenzyme banding patterns which allow differentiation of the first three species as apterous and alate adults and their instars using two enzymes ‐ carboxylesterase (EST) and phosphatase (P

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1989.tb06559.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryBiphenthrin was applied in the field to peach trees and tomato plants at rates of 2 and 4 g of biphenthrin a.i., 100 e.c. Talstar (Anon., 1983; FMC, USA)/100 litres of water. During the experimental period, three to four applications were made to peach trees and four to tomato plants at 14‐day intervals. Samples from peach foliage, peaches and tomatoes were collected at set post‐application dates and analysed for biphenthrin residues by GLC.The foliar residues of biphenthrin ranged from 65±1 (maximum to 25± 1 (minimum) ng/cm2and from 101±52 (maximum) to 35±7 (minimum) ng/cm2at the low and high rates of application, respectively. The residues of biphenthrin in the peach fruit peel ranged from 1016±367 (maximum) to 247±44 (minimum) ng/g for the low rate and from 2845 (maximum) to 368±15 (minimum) ng/g for the high rate of application. The maximum amount of biphenthrin residues measured in the peach pulp was 47±10 ng/g while at 21‐day after the third application and at 7‐day after the fourth application the residues present were at levels lower than the detection limit (1 ng/g) for the method applied. In whole tomatoes the residues of biphenthrin ranged from 119±14 (maximum) to 31±2 (minimum) ng/g. Plots of 1nC versus t, where C is the amount of biphenthrin ng/cm2of peach leaf surface or per gram of fruit tissues and t is the post‐application time in days, were constructed and the persistence half‐lives of biphen

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1989.tb06560.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummarySporulation of Botrytis cinerea was studied in vitro under various filters and polyethylene co‐polymer (PE) sheets. It was found that continuous darkness blocked sporulation completely. Sporulation was inhibited by reduced ultraviolet (u.v.) radiation. Almost total inhibition of sporulation was also found when cultures were grown under a blue filter. The reduction of spore formation was negatively related to the ratio of transmitted blue/u.v. light. The possibility of using this effect to control the incidence of Botrytis cinerea in greenhouses is discussed. A brief report has been published (Reuveni, Raviv, Allingham&Bar, 1988

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1989.tb06561.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryAn experiment designed to generate a wide variety of epidemics of Mycosphaerella graminicola without deliberate replication was done in two years. Disease severity was estimated at frequent intervals during the life of the crop and yields measured at harvest. Absolute estimates of disease severity were derived by regression of visual estimates on subsamples of leaves on which severity was estimated objectively using an image analysis system. Yield was predicted best by the integral of the square root of M. graminicola severity over the normal lifetime of each leaf, measured in thermal time. Only the top two leaves contributed to yield loss; no influence of the third leaf on yield was detected. Thousand grain weight was best predicted by the integral of the square root of M. graminicola severity on the flag leaf alone. Parameter estimates were similar in the two years. The prediction equations were consistent with yields observed in an experiment done in a third year using two sowing dates and two rates of nitrogen fertilisation, despite a much greater range of disease severity. Although critical point models could describe each year's results adequately, neither parameter estimates nor the growth stage at which the best relation occurred were consistent across years. The equations to predict loss may be useful for farmers in decision‐support systems which are based on predictio

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1989.tb06562.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryAn efficient protocol for differentiating cucumber (Cucumis sativus) seedlings resistant and susceptible to scab (Cladosporium cucumerinum) has been developed by examining the interacting factors of spore density and cotyledon growth stage. The procedure permitted both resistant and susceptible plants to be recovered. Seedlings were grown at 20°C and inoculated 1 day after emergence by placing a 5 μl inoculum droplet (2 × 106spores/ml) on the newly expanded cotyledons. Seedlings were incubated in a darkened dew chamber for 48 h at 20°C and 100% r.h., and then grown for 6 days at 20°C. Plants could be rated as resistant or susceptible 8 days after inocula

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1989.tb06563.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryExtracts from five West African plants were evaluated in vitro for fungitoxicity against Ustilago maydis, Ustilaginoidea virens, Curvularia lunata and Rhizopus sp. Steam distillate from leaves of Cymbopogon citratus completely inhibited the growth of all four fungi, and hot water extracts from fresh leaves of Ocimum gratissimum and Chromoleana odorata, and dry fruits of Xylopia aethiopica, reduced radial growth by 10–60%. A hot water extract from dry fruits of Monodera myrstica was ineffective as a fungitoxican

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1989.tb06564.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryA technique was developed for the reliable inoculation of Xanthomonas campestris pv. campestris into the cabbage host, in a manner which simulates a natural process of penetration. By introducing the inoculum into guttation droplets on the leaf margin, the bacteria are taken into the plant via the hydathodes, thereby avoiding mechanical injury to the plant and the possibility of producing artefacts. This technique, while being highly efficient, possesses several advantages over commonly used methods of inoculation.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1989.tb06565.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryCotton was grown in soils of differing phosphorus levels with and without a mycorrhizal fungus and with a range (0 to 3200 eggs/ 100 c‐3soil) of Meloidogyne incognita eggs added. Tolerance of cotton to M. incognita did not differ between plants grown in different soils with or without the mycorrhizal fungus, though plant size could differ markedly. Plant tolerance was increased by a delay in adding nematode

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1989.tb06566.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryCrataegus monogyna, Prunus spinosa, Fraxinus excelsior and Sambucus nigra, common woody species of hedgerows, were grown in pots and treated in June with half and full recommended rates of 15 herbicides and three plant growth regulators. C. monogyna was affected by fewest compounds, while the other three species showed differing tolerances. The wild‐oat herbicides, diclofop‐methyl, flamprop‐m‐isopropyl and difenzoquat did not adversely affect the shrubs. Plant growth regulators used at rates recommended for cereals and grassland had only minor effects. Clopyralid killed only S. nigra, while mecoprop, fluroxypyr, chlorsulfuron, metsulfuron‐methyl and glyphosate caused significant damage to most species. Height of C. monogyna was increased after treatment with diclofop‐methyl, difenzoquat, ethofumesate, mefluidide and

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1989.tb06567.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY