摘要:

SUMMARYPostharvest treatments, including insecticidal dips, isopropyl alcohol dips, insecticidal fogs and hot‐water immersion, were evaluated to control mixed infestations of Western Flower Thrips(Frankliniella occidentalis)and Melon Thrips(Thrips palmi)on dendrobium orchid blossoms. The limiting factor for all postharvest treatments was phytotoxicity, characterised by a loss of vase life that differed among cultivars. Insecticidal dips and insecticidal fogs were less phytotoxic than hot‐water immersion and isopropyl alcohol dips. Insecticidal fogs consisting of abamectin 2.0% e.c. and abamectin tank‐mixed with Pyrenone e.c. (6% pyrethrins, 60% piperonyl butoxide) reduced the mean number of thrips per blossom by 93.8% and 92.3%, respectively and were nonphytotoxic. An insecticidal aerosol, Floragas (2% permethrin and 0.1% pyrethrum dissolved in high pressure liquified CO2) reduced thrips by 33% to 54% with no phytotoxicity. Insecticidal dips for 3 min with agitation reduced the mean number of thrips per blossom by 43.7% to 99.1%. Of the 12 insecticides and one surfactant tested, only chlorpyrifos 44.4% e.c., fluvalinate 22.3% f., and chlorpyrifos 50% d.f. were both effective and nonphytotoxic. Immersion in water at 49.5°C for 15 and 20 s reduced the mean number of thrips per blossom by 88.1% and 95.3%, respectively. A 70% solution of isopropyl alcohol applied as a postharvest dip did not kill all thrips and was extremely phytotoxic to bl

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1995.tb05375.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SUMMARYThe effect of wind and rain on initiation of dispersal and subsequent distances moved by apterousSitobion avenaewas quantified in five laboratory experiments. Wind duration and type (steady and gusting), rain duration and intensity, and a combination of wind and rain were investigated. With increased duration of wind there was an increase in the average distance aphids moved. There was less movement when aphids were exposed to gentle gusting, than to steady wind or strong gusting. With increased duration of rain there was an increase in the proportion of aphids lost from plants. Under heavy rain, the proportion of aphids off the release plant, the distance moved by them and the proportion of aphids lost, was greater than for drizzle or light rain. When wind and rain were compared, rain had the greater impact on aphid dispersal. It was concluded that leaf disturbances caused by strong gusts of wind or large rain droplets are of considerable importance in the initiation of aphid dispersal, but that wetness alone is not.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1995.tb05376.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SUMMARYThe effects of food and temperature on the development of colour pigment in the hind wings of adult Colorado potato beetle,Leptinotarsa decemlineata(Say), were investigated. In a replicated study, adults were held at 18°C, 28°C and 18/28°C on potato foliage (Solanum tuberosumL.), potato tubers, or without food in controlled‐environment chambers. Representative subsamples of wings were collected at two‐day intervals, mounted on microscope slides, and photographed to document the progression of colour change. Observations were also made on elytral hardening over time.Hind wing colour developed more quickly at 28°C than at 18°C, and after three weeks had attained a deeper red colour at the higher temperature. Colour development was also more rapid when adult beetles were fed on foliage compared with tubers. In foliage‐fed beetles, elytra hardened more quickly at 28°C than 18°C, and many tuber‐fed beetles never developed hardened elytra, regardless of temperature treatment. Unfed beetles developed no hind wing colour pigment and their elytra remained soft for the duration of the experiment. Colour plates documenting wing colour development over time are presented; variation in colour development under the conditions tested, suggests that the use of hind wing colouration to estimate beetle age in the field may

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1995.tb05377.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SUMMARYThe effects of 10 fungicides on the growth ofColletotrichum coccodesin agar culture and on the germination of conidia was investigated. In field experiments in 1990 and 1991 the extent to which treating black dot‐affected potato seed tubers with fungicides affected the development of the disease on stem bases, roots and tubers was assessed. Black dot was also assessed on plants from field trials in 1990 which were designed to investigate the efficacy of the soil sterilant 1,3‐dichloropropene (Telone) and two nematicides, aldicarb (Temik) and ethoprophos (Mocap).Prochloraz and fenpiclonil were the most effective fungicides in decreasing the size of C.coccodescolonies on agar. Imazalil, propiconazole and dichlorophen were also effective, but at higher concentrations, whereas tolclofos‐methyl, thiabendazole and benomyl were only moderately effective. Resistant sectors developed from inhibited colonies on agar containing fenpiclonil and tolclofos‐methyl. Conidial germination was prevented at 1 mg/litre fenpiclonil and 5 mg/ litre dichlorophen; imazalil, benomyl and thiabendazole were also moderately effective.Fenpiclonil and propiconazole seed tuber treatments consistently decreased black dot infection on roots, stem bases and daughter tubers early in the season, but only fenpiclonil decreased disease on tubers at harvest in October. Propiconazole also delayed emergence and decreased stem numbers. Soil treatment with 1,3‐dichloropropene, aldicarb or ethoprophos had no effect on black dot butRhizoctonia solanituber infection and black scurf were

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1995.tb05378.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SUMMARYA total of 144 isolates ofMicrodochium nivalefrom stem bases of winter wheat were taken from 30 sites and 91 isolates from grain were taken from seven sites throughout the UK. Identification by polymerase chain reaction (PCR) amplification of the internal transcribed spacer (ITS) region followed by restriction enzyme digestion of the PCR product revealed that 70% of stem base isolates wereM. nivalevar.majusand 30% var.nivalewhile 93% grain isolates were var.majusand 7% var.nivale.Almost all isolates were resistant to the benzimidazole fungicide benomyl. Perithecial productionin vitrowas more common in var.majusisolates and occurred in almost all grain isolates, but was less common in stem base isolates. The implications of the findings in terms of epidemiology and chemical control of this important cereal pathogen are discussed.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1995.tb05379.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SUMMARYA field survey was performed during the summers of 1991 and 1992 to determine whether blueberry leaf mottle virus (BLMV) infects wild blueberry bushes surrounding commercial blueberry fields and might act as a reservoir of the virus. Leaf samples from wild blueberries growing in wooded areas surrounding commercial plantings in Western central Lower Michigan were taken from bushes radiating out from the border of the commercial field into the wooded areas at 5, 50 and 100 m. BLMV was present in native bushes ofVaccinium corymbosum, V. myrtilloidesandV. angustifolium, and two hybrids ofV. corymbosum V. angustifolium.BLMV‐infected pollen grains were detected in pollen traps located up to 2 miles from a source fiel

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1995.tb05380.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SUMMARYThe systemic movement of citrus tristeza virus (CTV) in sour orange(Citrus aurantium)seedlings and of citrus exocortis viroid (CEVd) in Etrog citron(C. medica)seedlings was studied. The movement of the two pathogens was analysed by detection in sections of roots and stems at different time intervals. Both pathogens were detected initially in the basal parts and the roots and subsequently spread to the shoot. CTV and CEVd moved in young citrus seedlings at similar rates. The findings are consistent with long distance phloem transport of the virus and the viroid. The practical implications of the pattern of systemic movement for diagnosis of infected trees are discussed.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1995.tb05381.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SUMMARYIsolates of novel strains of Kashmir bee virus (KBV) were obtained from field‐collected dead adults ofApis melliferafrom honey bee colonies in Canada and Spain. They differed from other strains of KBV in their tendency to aggregate in dilute buffer solution and in containing only three proteins when analysed by SDS‐polyacrylamide gel electrophoresis compared with five proteins resolved in the type strain of KBV fromApis ceranain India and six proteins in KBV strains from South Australia and New Zealand. Immunodiffusion tests and Western blotting studies indicated that the five virus isolates were serologically related and all were related to acute paralysis virus (APV). The world distribution of KBV strains and their apparent relationship with APV are discus

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1995.tb05382.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SUMMARYA triple antibody sandwich enzyme‐linked immunosorbent assay (TAS‐ELISA) with a monoclonal antibody was developed and evaluated for the detection of prune dwarf virus (PDV) in sweet cherry trees(Prunus avium).An independent reverse transcribed polymerase chain reaction test was also developed to establish, in conjunction with a bioassay, the incidence of PDV in 40 sweet cherry trees and to confirm the absence of virus in 15 control trees. Trees with two‐thirds of their leaves positive for PDV would be identified with 99% probability by testing four leaves per tree with TAS‐ELISA. The monoclonal antibody did not cross‐react withPrunusnecrotic ringspot virus in the

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1995.tb05383.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SUMMARYPotato mop‐top virus (PMTV) was detected by ELISA in primary zoospores from four out of six isolates ofSpongospora subterraneaf.sp.subterranea.One virus‐free isolate (N) ofS. subterraneawas used to acquire PMTV from potato roots and to transmit the virus to healthy plants. A mono‐fungal culture ofS. subterranea(isolate N) was derived by infecting tomato plant roots with a single cystosorus. The culture was used successfully to acquire PMTV from the roots of infectedNicotiana debneyiplants that had been manually inoculated with virus isolates, and subsequently to transmit the virus to healthy bait plants. These experiments confirm thatS. subterraneais a vector of PMTV. Two PMTV isolates that had been maintained by manual inoculation for 19 and 21 passages were also acquired and transmitted by the fungus cu

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1995.tb05384.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY