摘要:

SummaryThe colonisation of orchards byBlepharidopterus angulatus(the black‐kneed capsid bug) from alder windbreaks was investigated, to determine its use as a biological control agent of orchard pests. The aphidPterocallis alniprovides an abundant and acceptable food for the capsid on alder. The key capsid mortality factor on windbreaks was the loss of adult females through migration. Clipping the windbreak prior to the aphid population peak resulted in male capsids migrating and females remaining, while clipping after the aphid population peak resulted in both sexes migrating to nearby orchards. Guidelines are given for windbreak management as part of a system of integrated orchard pest contro

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1989.tb02099.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryDiuraphis noxiainfestations were monitored in early winter and winter wheat during 1983–1985. The aphid population increase was logarithmic in all three years and on both cultivars 100 % infestation levels were recorded. The period of exponential increase in both percentage infestation and in the number ofD. noxiaper stem took place when the plants had reached the stem elongation stage. The mean number recorded at peak population levels was 150–160 aphids per stem. During the period of plant senescence numbers dropped rapidly. Large reductions in yield were recorded on all infested plants. Single‐plant data showed that yield reductions in the early winter cv. Betta were related to the duration of infestation. Relative to sprayed controls, reduction in kernel mass ranged from 25–80% and in 1000‐kernel mass from 15–45%. However, the yield reductions of the faster‐growing cv. Flamink, appeared to be dependent on the number of aphids per plant during the later growth stages and not the duration o

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1989.tb02100.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryEmasculated flowers of several black currant cultivars were pollinated and then inoculated with dry conidia ofBotrytis cinereain the field and glasshouse. The infection of pistils was examined by U.V. fluorescence microscopy and the incidence of premature flower abscission recorded. Conidia germinated in the stigmatic fluid in all cultivars and hyphae spread symptomlessly throughout the style to infect the pericarp and ovules.Of six cultivars inoculated in the field, cv. Ojebyn was the most, and cv. Ben More the least resistant to flower shedding. Natural infection of stigmas byB. cinereawas common in the field and a high proportion of apparently healthy non‐inoculated flowers which abscissed were found to contain infected ovules. Fewer flowers abscissed if inoculations were made 6 days after pollination. Symptomless or latent infection of black currant flowers byB. cinereamay be a contributory cause of premature abscission of developing fruits, or ‘running‐off’, recorded in these expe

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1989.tb02101.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryIn 1983 and 1984, potato seed tubers of five early and seven maincrop cultivars were inoculated with cultures ofRhizoctonia soluniduring planting to simulate severe seed infection. Shoot and stolon infection was assessed in June‐August and black scurf on tubers recorded after harvest in October.Almost all shoots of all cultivars had stem canker in both years and disease on shoots, stolons and tubers was more severe in 1984 than in 1983. In 1983 similar amounts of disease developed on all early cultivars and between 11% (Ulster Sceptre) and 32% (Maris Peer) shoots were pruned off. Maris Peer had a stem canker score lower than other cultivars in 1984 but more than half the shoots were pruned off. Shoot pruning on Estima, Ulster Prince and Ulster Sceptre was more common on plants from sprouted than non‐sprouted seed. Between 30 and 50% of stolons were pruned off. After harvest in 1985, black scurf was least prevalent on Arran Comet and Maris Peer tubers and in 1984 on Arran Comet and Estima tubers from non‐sprouted seed.Of the maincrop cultivars, King Edward plants from sprouted seed had many shoots pruned off in both years. Shoot pruning was also prevalent on Maris Piper and Pentland Squire plants from non‐sprouted seed. Record had fewest pruned shoots and stolons and the lowest stem canker score. The disease was more severe on Pentland Crown and Maris Piper plants from non‐sprouted than sprouted seed. Black scurf was most common on Cara and King Edward tubers in 1983 and on King Edward and Record tubers in 1984.In both years few shoots but many tubers were infected on plants from non‐inoculated seed and the significance of this i

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1989.tb02102.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryIn 1983 and 1984, potato seed tubers of five early and seven maincrop cultivars were inoculated with cultures ofRhizoctonia solaniduring planting in field experiments to simulate severe seed infection. The size of foliage was assessed during June‐August and tuber yields recorded during growth and at harvest in October.Stem canker delayed shoot emergence, decreased the number and length of stems and caused increased variation in stem length; these effects were greatest with Maris Peer and Arran Comet (early cultivars) and King Edward and Pentland Squire (maincrop cultivars). Total weight of foliage was decreased, especially with earlies, dry matter of stems increased and the proportion of foliage on lateral stems increased.With the early cultivars, tuber yield from sprouted Maris Peer seed 11 wk after planting in 1983 was decreased by 24%, and 13 wk after planting in 1984 yields were decreased by 42% (Maris Peer), 40% (Ulster Sceptre), 34% (Estima), 30% (Arran Comet) and 17% (Ulster Prince) with sprouted seed and by 20, 29, 53, 39 and 28% respectively with non‐sprouted seed. Decrease in total yield at harvest in October averaged 13% with sprouted seed and 10% with non‐sprouted seed. In all cultivars the weight of small tubers was decreased and with Estima the weight of large tubers was increased.Tuber bulking was also delayed with all maincrop cultivars and at harvest yields from sprouted King Edward seed were decreased by 13% in 1983 and by 16% (sprouted seed) and 23% (non‐sprouted seed) in 1984; yields of Pentland Squire were decreased by 5, 16 and 21% respectively. Yield losses with other cultivars ranged from 5–13% with sprouted seed and 0–16% with non‐sprouted seed. The yields of small tubers were decreased with all cultivars and yields of large tubers were increased with Pentland Squire, Pentland C

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1989.tb02103.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryMouse monoclonal antibodies (MAbs) specific for potato virus M (PVM) were prepared and the properties of three of them were studied. MAb M4C1 is IgG2b, it binds with high affinity to PVM coat protein, to purified virus preparations and recognises PVM in infected potato leaves and tubers. MAb M6D5 is IgG2a and also reacts with PVM coat protein, purified PVM and with PVM in potato leaf and tuber extracts. In double‐antibody sandwich ELISA (DAS ELISA) MAbs M4C1 and M6D5 reacted with all 17 PVM isolates tested. MAb M7 is IgG2b and recognises PVM only in indirect dot ELISA on nitrocellulose filters and viral coat protein on Western blots.MAbs against PVM were used as capture antibodies and europium‐labelled MAbs as conjugates in time‐resolved fluoroimmunoassay (EuTRFIA). The standard EuTRFIA curve of PVM detection is approximately linear over a range of PVM concentrations from 0.5 ng/ml to 1000 ng/ml. The lowest PVM concentration detectable in EuTRFIA was 0.5 ng/ml and correspondingly 6 ng/ml in DAS ELISA. The use of the europium chelate label allows PVM detection in potato leaf and tuber sap at dilutions greater than 10‐‐4with very low background fluorescence. EuTRFIA with MAbs, with either one or two incubations is about 10–20 times more sensitive for PVM detection than is DAS ELISA. PVM and PVX, mixed with healthy potato tuber sap, were simultaneously tested in a single sample at concentrations lower than 10 ng/ml by double‐label TRFIA using europium‐labelled MAbs to PVM and samarium‐lab

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1989.tb02104.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryA rapidly spreading decline of ‘Minneola’ tangelos, ‘Shamouti’ and ‘Valencia’ sweet oranges grafted on sour orange rootstock in the Morasha area, in the coastal plain of Israel, was found to be caused by a severe ‘seedling yellows’ strain of the citrus tristeza virus (CTV). Repeated ELISA tests revealed great variation in distribution of CTV throughout the canopies, even in declining trees. In a substantial number of the declining trees, samples of up to 10 twigs per tree were not always sufficient for CTV detection. The ELISA values (O.D. 405 nm) in the parts found infected were high, whereas in most of the twigs showing negative ELISA results the virus was absent as indicated by biological indexing. The Morasha strain of CTV was also characterised by rapid annual spread rates. The ratio D/E (the proportion of Declining trees found among ELISA‐positive ones) is proposed as a simple index of strain severity. The epidemiological consequences of the uneven distribution of CTV and rapid decl

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1989.tb02105.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryA leaf disease of sorghum (Sorghum bicolor) characterised by fine discontinuous chlorotic streaks between the veins, was observed on sorghum grown during the 1987/88 post‐rainy season in peninsular India. Early‐infected plants were stunted, had shortened internodes, and produced poorly developed panicles. The virus was transmitted by the delphacid planthopper,Peregrinus maidis. Negatively stained leaf dip preparations contained bullet‐shaped virus particles (208 ± 4.4 × 66 ± 1.0 nm) resembling those of rhabdoviruses. In ultrathin sections, the particles budded through the inner nuclear membrane and were present in the cytoplasm within membrane‐bound vesicles that were apparently contiguous with the distended outer nuclear membrane. A method for purifying the virus was developed utilising polyethylene glycol (PEG) precipitation, Celite filtration and sucrose densitygradient centrifugation. An antiserum was produced in rabbits with a titre of 1/2650 in the precipitin ring interphase test. The virus could be detected in infected sorghum leaf tissues using a direct antigen coating form of enzyme‐linked immunosorbent assay (DAC‐ELISA). In immuno‐double diffusion tests, the virus reacted positively with antisera to maize mosaic virus (MMV) from Reunion (MMV‐RN) and Hawaii (MMV‐HI), but not with antisera to barley yellow striate mosaic (BYSMV), cereal chlorotic mottle (CCMV), and cynodon chlorotic streak (CCSV) viruses. Thus, the virus isolated from sorghum is designated the MMV‐S isolate. In DAC‐ELISA tests, MMV‐S reacted positively with antisera to MMV‐R, MMV‐HI, MMV‐Florida isolate, CCSV, and CCMV, and weakly with antiserum to BYSMV. SDS‐polyacrylamide gel electrophoresis revealed four major proteins of relative mass Mr70 000, 59 000, 32 000 and 28 000. In electro‐blot immunoassay, MMV and CCSV antisera detected the G and N proteins. These data suggest that MMV‐S should be placed in the sonchus yellow net

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1989.tb02106.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryOne hundred and eighty‐nine isolates of pea seedborne mosaic virus (PSbMV) were obtained from seedlings of 435 pea (Pisum sativum) germplasm introductions originally acquired from India, Turkey, Latin America and Europe. Fifty‐eight per cent of the isolates were identified as belonging to pathotype P‐1, 22% to pathotype P‐4, and 7% to the mild form of the lentil pathotype L‐1. Some isolates could not be classified into any known pathotype and need further study. No isolate appeared to present a threat to peas beyond that already known to exist with previously described forms of

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1989.tb02107.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

SummaryA strain of raspberry bushy dwarf virus (RBDV‐RB), discovered in England in 1981, readily infects by grafting many raspberry cvs that have geneBu, which confers strong resistance or immunity to isolates of the common strain. Haida is one of two cultivars that are highly resistant or immune from RBDV‐RB, but both its parents, cvs Creston and Malling Promise, are infectible. Studies of the segregation of resistance to both RBDV‐RB and a common strain of RBDV (D200) in four progenies related to cv. Haida or its two parents, showed that resistance to RBDV‐RB was heritable and occurred when geneBuwas present with a second resistance component whose inheritance is probably multigenic. There was some indication that the second component might be a form of partial resistance to graft inoculation of varying expression, and that cv. Haida possesses this resistance at a high level that has not been distinguished from immunity in the graft inoculations used. Cultivars Creston and Malling Promise possibly have this resistance to a lesser degree, while resistance in cv. Heritage has been distinguished from immunity only by extensive graft tests. Some possible implications for breeding RBDV‐RB resistant cultivars are

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1989.tb02108.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY