摘要:

SUMMARYIn four field trials from 1978 to 1980, sprays of codling moth granulosis virus (CpGV) plus 1·0% skimmed milk powder did not significantly affect damage to fruit by leaf rollers (tortrix moths). In laboratory tests, survival of larvae of the leaf rollerArchips podanafed on leaves sprayed with CpGV plus milk was unaffected and they grew faster than on unsprayed leaves, because of the milk deposits. This might increase damage byA. podanaif CpGV plus milk were applied during the feeding period of this species. In one field trial an unusual infestation of fruit by larvae of pith mothBlastodacna atrawas not affected by CpGV. Azinphos‐methyl significantly reduced damage byB. atruand, in one field trial where sprays were correctly timed, that by leaf rollers. CpGV had no consistently significant effects on numbers of fruit tree red spider mitePanonychus ulmior its predators, whereas azinphos‐methyl induced outbreaks of P.ulmiby killing its preda

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb05591.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYTwenty isolates of potato leafroll virus (PLRV) were readily transmitted byMyzus persicaefrom a wide range of potato cultivars toPhysalis floridana.The isolates also infectedMontia perfoliatabut not turnip or broad bean, and all were readily detected by direct enzyme‐linked immunosorbent assay. Four isolates, selected to represent the range of differences in severity of symptoms inP. floridana, also induced symptoms of differing severity inM. perfoliata, but their virulence in one species did not necessarily parallel that in the other. In general, virus concentration increased with increasing symptom severity. None of these four isolates was transmitted readily byMacrosiphum euphorbiaeand their particles were antigenically indistinguishable in gel‐diffusion precipitin tests.Further tests on one PLRV‐infected potato plant from which virus was at first not transmitted byM. persicaeshowed that it contained a poorly‐transmissible isolate (isolate 15). The inefficient transmission of this isolate could not be attributed to inadequate uptake or retention byM. persicaeof virus fromP. floridana, and aphids failed to transmit isolate 15 when it was acquired from purified preparations in membrane‐feeding tests. Although the poor aphid transmissibility of isolate 15 is therefore an intrinsic property of its particles, these were antigenically indistinguishable from the particles of readily aphid‐transmissible isolates.Immunoelectron microscopy tests showed that PLRV and beet mild yellowing virus are antigenically clos

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb05592.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYA method for producing up to 2000 million infectivesof Neoaplectana bibionisper container is described and is applicable to other species ofNeoaplectanaandHeterorhabditisspp. The nematodes were cultured within autoclavable plastic bags, on crumbed polyether polyurethane sponge coated with chicken offal homogenate that had been sterilised and inoculated with the primary form of the appropriate symbiotic bacterium(Xenorhabdusspp.). Procedures for extracting and cleaning the nematodes on a large scale are described. Nematodes were stored and transported on clean sponge in aerated polyethylene tubes. The techniques are suitable for industrial use with little further development.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb05593.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYIn a 4‐yr field experiment on a mineral soil infested with beet cyst nematode (Heterodera schachtii) the relationship between root yield of sugar beet (y) and initial population ofH. schachtii(Pi) fitted the equation:y=ymin +(ymax ‐ymin)ZPi‐Tymin = 7·7 t/ha,ymax = 39·4 t/ha, 2 = 0·99938 and T= 0 eggs/100 g soil. From this information and that obtained during a recent survey of 2766 beet fields, the total national root yield loss caused byH. schachtiiwas estimated as approximately 10 000 t/annum on mineral soils and (assuming a similar yield loss relationship on all soil types) 30 000 t/annum on organic soils.No consistent differences in efficiency of extracting cysts were found between the Fenwick Can and the flotation column. A bioassay technique was as effective as cyst extraction techniques in identifying infest

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb05594.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYComparisons are made between the population dynamics of potato cyst nematode and root growth of Pentland Crown and Maris Piper potato cultivars. Large changes in the number of eggs occurred to a depth of 48 cm, particularly in a peaty loam and in plots treated with oxamyl. Oxamyl delayed the hatch of eggs in the peaty loam but not in the sandy loam, giving the protected plants several weeks without invasion damage during which they became bigger with their roots better established deeper in the soil. Oxamyl killed or impaired the movement of second stage juveniles but appeared to have little systemic activity to hinder juvenile development within roots.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb05595.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYNematophagous fungi, both predators and endoparasites, were found to be common components of activated sludge. Although rotifers and ciliate protozoa (both potential prey) were also abundant, no fungi were parasitic on these organisms. Endoparasitic fungi, which were far more abundant than predators, were able to infect nematodes and complete their life cycles successfully. Neither of the predatory fungi observed were able to produce conidia: an unidentified net‐forming species lived saprophytically and failed to capture any prey, although it played a minor role in the formation of microbial flocs, and a single conidium ofDactylella mammillatawas observed to capture a nematode by spontaneous trap formation. Several endoparasites were recorded although single species dominated each sludge examined; these wereMeria coniosporaandCatenaria anguillulae.Both endoparasites were related to the population dynamics of the nematodes with 100% of the nematode population becoming infected at certain times. Clear predator (parasitetprey (host) associations were discernible and these are discusse

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb05596.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYWinter wheat varieties were treated with the wild‐oat herbicides difenzoquat and diclofop‐methyl at several growth stages in a series of four field experiments.High rates of difenzoquat damaged the winter wheat varieties Bouquet, Sportsman, Hobbit and Maris Huntsman but not Hustler. Treatment of the sensitive varieties during tillering stimulated excessive tiller production, resulting in more ears with fewer and smaller grains than on the unsprayed controls; later applications reduced the number of grains and severely depressed yield.In contrast, the early applications of diclofop‐methyl, during tillering, were more damaging than the later ones. Bouquet was more tolerant of diclofop‐methyl than were the other varieties

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb05597.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYThe importance of the silica content of the plant as a protection against dipterous stem‐borers was studied. Levels of silica in the stubble were inversely related to the degree of infestation by stem‐borers in 13 varieties of established swards of Italian ryegrass and also in newly‐sown swards of four varieties. There were significant reductions in larval colonisation of Italian ryegrass (cv. RvP) grown on soil watered with sodium silicate solution. A small range of silica content in the stubble was related to large differences in the level of attack by stem

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb05598.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYParental lines (inbred and hybrid male‐sterile lines and inbred pollinators) of prospective F, hybrids from the NVRS spring‐sown bulb onion breeding programme were examined to study their floral biology and aspects of pollination under glasshouse conditions. Inbreeding depression occurred in both pollinator and male‐sterile inbreds in terms of reduced flower numbers per umbel and a greater proportion of defective pistils. Male‐sterile and male‐fertile lines differed in their stigma and style characteristics and pattern of development. At flower opening, the styles of male‐sterile lines were longer and the stigmatic knob became receptive relatively sooner. The inbred male‐sterile line II/3 ms appeared to have a reduced receptive area on its stigmatic knob and remained receptive for a relatively shorter period. Individual lines differed for time of flowering, nectar content and its sugar concentration, and in their effectiveness as male and female parents as judged from pollen tube growth down the style in specific pairings. Assessment of pollen viability using the fluorescein diacetate test did not correlate with assessments based on pollen grain germination and subsequent growth down the style, perhaps as a result of differential receptivity in the inbred lines tested.These results are discussed in relation to future hybrid se

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb05599.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

SUMMARYGuayule seedlings were inoculated with twoGlomusspecies in pasteurised soil and grown in the glasshouse without added fertiliser for 8 wk prior to transplanting to the field. The survival rate of transplanted guayule seedlings was increased by inoculation with vesicular arbuscular mycorrhizal fungi compared with uninoculated controls. Inoculated guayule had greater concentrations of Ca, Fe, Mg and Mn at six months of age, and greater concentrations of Ca, Mg, and Zn at 12 months of age than did uninoculated plants. The latex content of both roots and shoots of guayule was greater in inoculated than in uninoculated guayule plants at 12 and 18 months of age. The resin content remained unchanged between treatments irrespective of sampling date.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1984.tb05600.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY