摘要:

SummaryFifty‐one pesticides currently registered for use in the UK were tested in the laboratory against Western Flower Thrips(Frankliniella occidentalis)maintained on chrysanthemum leaf discs. In an initial screening trial of the pesticides against larval thrips, 14 caused more than 75% mortality three days after exposure. These were tested further against adults and pupae and retested against larvae. A series of glasshouse trials were conducted using the most efficacious pesticides evaluated earlier. Granular and systemic compounds were included in the glasshouse trials since these could not be evaluated satisfactorily in the laboratory. Malathion proved to be the most potent chemical currently registered for control of thrips on a wide range of horticultural crop

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb03434.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryMeasurements of feeding damage by sitona weevil (Sitona lineatusL.) adults on differing numbers of seedlings of white clover (Trifolium repensL.) at the first and fourth trifoliate leaf stage were made in the glasshouse at 20°C.S. lineatusconsumed more of the trifoliate component of the seedling. Sitona adults caused significant yield reduction at all levels of plant population. Total clover consumption increased with increasing size of sitona population, but consumption per adult weevil was reduced

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb03435.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryA fluorescent spray tracer was used to measure the profile of spray deposits through winter‐wheat crop canopies and upon beneficial insects, placed in fixed positions which approximated to their natural distributions. Tracer deposition profiles were recorded on a series of occasions between G.S. 47 to G.S. 90. Deposition levels declined through the canopy on each occasion but the proportion of the spray reaching the ground varied between growth stages. Deposition rates upon insects followed the same trends but insects on the aerial parts of the plant received a higher volume of tracer per unit area than the part of the crop that they were placed upon. Insects placed on the ground received a dose equivalent to their ground area. For a given distribution of insects, these data permit direct spray exposure to be estimated. The general application of the method to a wide range of crops, to the calculation of risk indices, to the standardisation of field tests and to the development of selective spray placement methods are discusse

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb03436.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryIn a project aimed to incorporate downy mildew resistance into sorghum hybrid seed parents, we screened F4and F5families for resistance to the ICRISAT Centre isolate of the pathogen using a greenhouse seedling screening technique. The families originated from a cross of 296B (susceptible) and IS 18757 [(QL‐3) resistant]. The F4s were obtained from agronomic selection in F2s and F3s, and the F5families from advancing plants identified as resistant in segregating F4families.The resistant plants were more than double the number of susceptible plants in the F4and almost so in the F5suggesting that resistance to downy mildew was dominant. Of the four genetic models examined (a single‐locus model and three two‐locus models with complementary, inhibitory, and a combination of complementary and inhibitory interactions), the two‐locus model with independent segregation and a combination of complementary and inhibitory inter‐allelic interaction appeared to be most appropriate in explaining the segregation patterns within and among F4and F5families. Accordingly, for resistance toP. sorghi, the suggested genotypes for IS 18757 isPlaPlaPlbPlband for 296B isPla

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb03437.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryA virus causing sunken veins on ‘Georgia Jet’ sweet potato, and yellow brittle leaves and stunting onIpomoea setosa, was purified and a specific antiserum was prepared. Flexuous particles with a normal length of 850 nm and a diameter of 12 nm with an open helical structure typical of closteroviruses were observed. The virus particle protein has an apparent mol. wt ofc.34 kD. Double‐stranded RNA isolated from SPSVV‐infectedI. setosaand subjected to electrophoresis in agarose consisted of one major band with an estimated Mrof 10.5 kbp and two minor bands with Mrof 9.0 and 5.0 kbp. Fibril‐containing vesicles in phloem cells were observed in ultrathin sections of infected leaf tissues. The virus was transmitted by the whiteflyBemisia tabaciin a semi‐persistent manner and by grafting, but not mechanically. The virus could be transmitted to variousIpomoeaspecies, toNicotiana clevelandii, N. benthamianaandAmaranthus palmeri.The virus did not react with an antiserum to lettuce infectious yellows virus. Based on particle morphology, serology and symptom expression, the virus appears unique and different from all other reported whitefly‐transmitted closteroviruses. We propose it be named “sweet potato sunken vein

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb03438.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryThe RNA genome of bean yellow mosaic virus (BYMV) was detected in gladioli corms by reverse transcription and polymerase chain reaction (PCR). However, a positive signal was not obtained from some infected corms because the virus concentration was below the sensitivity limits of PCR. Virus was detected in these corms by using a modified protocol in which transcription of the PCR products by T7 RNA polymerase yielded an additional 10‐ to 100‐fold signal amplification.The relative concentrations of BYMV in gladioli corms were evaluated using PCR. Virus accumulation in corms was found to be a 100 times lower than in leaves, and be within the range of picogram quantities of viral RNA per gram fresh weight of corm tis

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb03439.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryFragmented shoot apex culture (FSAC) was used to eliminate some diseases caused by viruses and virus‐like agents from 24 varieties of imported grapevines. Each cultivar was examined by biological indexing before and after FSAC. Graft indexing revealed that leaf roll, stem pitting and yellow speckle diseases were common before FSAC. A correlation was observed between the incidence of leafroll disease and the presence of specific dsRNA species which were removed after FSAC. One of these species, an RNA of about one kilobase pair was associated with low yielding Sultana clones. Both biological indexing and dsRNA assay indicated no recurrence of the leafroll disease in material regenerated by FSAC even after 10 years in the field. It is concluded that dsRNA assay may be used as a faster and less expensive method than biological indexing in assessing the success of leafroll elimination by FSAC. The test also provides some information on the genome size of the viruses associated with leafroll disease. Graft indexing indicated that yellow speckle disease was resistant to elimination by FSAC, while stem pitting was removed from some of the vines and the grapevine fleck disease was eliminated from most source

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb03440.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryThe relationships among fifteen isolates of whitefly‐transmitted geminiviruses (WTGs) from North, Central and South America and six from other continents were assessed (a) in nucleic acid hybridisation tests with sulphonated DNA probes for eight of the viruses, and/or (b) in triple‐antibody‐sandwich ELISA with panels of monoclonal antibodies (MAbs) to particles of African cassava mosaic virus (ACMV) and Indian cassava mosaic virus (ICMV). Probes specific for DNA‐A of four American viruses, abutilon mosaic (AbMV), bean golden mosaic (BGMV), squash leaf curl (SLCV) and tomato golden mosaic (TGMV), detected virtually all the American viruses but reacted weakly if at all with ICMV, ACMV or tomato yellow leaf curl virus from Thailand (TYLCV‐T). Conversely, the probe for ACMV DNA‐A did not detect any of the American viruses, and that for TYLCV‐T DNA‐A reacted weakly with SLCV and TGMV0020but did not detect the others. In contrast, probes specific for DNA‐B of the four American viruses or ACMV detected only the homologous virus, except for slight reactions between the AbMV DNA‐B probe and both chino del tomate virus (CdTV)‐DNA and SLCV‐DNA. However, a probe for DNA‐B of bean calico mosaic virus (BCMoV) reacted weakly with BGMV‐PR DNA, and a probe for DNA‐B of CdTV from Mexico detected several American viruses.Six out of 17 MAbs specific for ACMV and six out of 10 MAbs specific for ICMV reacted with one or other of the 14 American virus isolates tested. Two and‐ACMV MAbs reacted with all, and one anti‐ACMV MAb and two anti‐ICMV MAbs reacted with nearly all the American viruses, one anti‐ACMV MAb reacted with about half the American viruses and six other MAbs reacted with only one or two of them. Of the American viruses, CdTV and AbMV were the least closely related to the others. The epitope profiles of BCMoV, BGMV, cotton leaf crumple virus, serrano golden mosaic virus and SLCV were virtually indistinguishable. TGMV, potato yellow mosaic virus (PYMV) and an euphorbia virus had profiles intermediate between those of the BGMV cluster and AbMV‐CdTV. In general, the epitope profiles and the results of hybridisation tests with DNA‐A probes show that the similarities among the American viruses are greater than those between the American viruses and the viruses from other continents; the hybridisation tests with DNA‐B probes show that substantial differences exist between individual American viruses. In America, geminivirus evolution seems to have proceeded convergently from different progenitor viruses, or divergently from one ancestral form, with DNA‐B diverging to a greater ex

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb03441.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummarySelected monoclonal antibodies (MAbs), prepared to particles of African cassava mosaic or Indian cassava mosaic geminiviruses, detected three geminiviruses that occur in Europe: abutilon mosaic virus inAbutilon pictum ‘Thompsonii’, tobacco leaf curl virus inLonicera japonicavar.aureo‐reticulataand tomato yellow leaf curl virus inLycopersicon esculentum.All three viruses were detected in indirect ELISA by MAbs SCR 17 and SCR 20 but they were differentiated by their reactions with SCR 18 and SCR 23. Tobacco leaf curl virus was detected only when reducing agents were included in the leaf extraction medium. Inclusion of sodium sulphite slightly improved detection of tomato yellow leaf curl virus but reducing agents were not needed for detection of abutilon mosaic

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb03442.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY

摘要:

SummaryBarleys with and without the Yd2resistance factor, wheat alien addition stocks with other barley yellow dwarf virus (BYDV) resistance factors and true wheats were challenged with three Australian isolates of BYDV‐RPV. Yd2resistance was effective against two of the BYDV‐RPV isolates and inoculated barleys which carry Yd2did not develop BYD symptoms and shoot growth was not affected. However, barleys with Yd2were susceptible to the third BYDV‐RPV isolate. All barley lines inoculated with the third virus isolate developed typical BYD symptoms (yellowing), shoot growth was reduced compared to uninfected controls and virus titres determined by ELISA were high and similar in barleys with and without Yd2. In contrast, resistances fromThinopyrum intermediumandAgropyron pulcherrimumin wheat backgrounds were effective against all three BYDV‐RPV isolates. Shoot growth of inoculated plants with either of these resistance factors did not differ from uninfected controls and virus titres determined by ELISA were v

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1992.tb03443.x

出版商:Blackwell Publishing Ltd    

年代:1992

数据来源: WILEY