The occurrence and effects of barley yellow dwarf virus in maize in SW England     

M. N. PEARSON  SHEILA M. ROBB 《Plant pathology》1984,33(4):503-512

During 1975 and 1976 barley yellow dwarf virus was isolated, using the aphid Rhopalosiphum padi (L.) from five maize cultivars in the Exeter area. The isolates produced interveinal flecking, often accompanied by leaf reddening, in the maize cultivar Anjou 210 and several other susceptible cultivars. ln 1976 visual assessment of six commercial maize plantings indicated natural infections ranging from 11 to 14% of plants, whilst infection in a disease observation plot ranged from 0.8 to 27.5%. Population counts for the three aphid vectors Sitobion avenae (F.), Metopolophium dirhodum (W.) and Rhopalosiphum padi (L.), associated with the crop, corresponded closely with the Rothamsted Insect Survey results from Starcross, Devon.
The maize cultivars Anjou 210 and De Kalb 202 were grown in experimental plots with individual rows containing 0, 25, 50, or 100% barley yellow dwarf-infected plants. Infection caused severe stunting of Anjou 210 but had less effect on De Kalb 202. Dry matter yield losses of 50% for Anjou 210 and 27% for De Kalb 202 were recorded; there were also significant changes (p<0.05) in dry matter content, metabolisable energy, digestible crude protein and water soluble carbohydrate.  相似文献   

Vanilla viruses in the South Pacific   总被引：1，自引：0，他引：1  

M. N. PEARSON  G. V. H. JACKSON  S. P. PONE†  R. L. J. HOWITT 《Plant pathology》1993,42(1):127-131

Surveys for viruses affecting Vanilla fragrans and V. tahitensis carried out in Cook Islands, Fiji, Niue, Tonga and Vanuatu detected cymbidium mosaic potexvirus and odontoglossum ringspot tobamovirus in all countries; vanilla necrosis potyvirus in Fiji, Tonga and Vanuatu; and vanilla mosaic potyvirus in Cook Islands, Fiji and Vanuatu. For all these viruses the surveys extended the previously known distribution in the South Pacific. Other, unreported potyviruses and rhabdovirus-like particles were detected from Fiji and Vanuatu. Symptoms associated with potyvirus infection (leaf distortion, sunken chlorotic patches, stem necrosis and vine die-back) were found in a majority of plantings in Fiji, Tonga and Vanuatu; in Fiji and Tonga there were instances where up to 50% of the plants in farmers' plots were affected.  相似文献   

Localized tumours of the canine small intestine: a report of twenty cases     

CHRISTINE GIBBS  H. PEARSON 《The Journal of small animal practice》1986,27(8):507-519

During a 10 year period. 20 dogs with primary localized neoplasia of the small intestine were presented at the University of Bristol Veterinary School. Half the tumours were carcinomas, the remainder being lymphosarcomas (5 cases), leiomyosarcomas (3 cases) and leiomyomas (2 cases) Lesions occurred at a variety of locations along the tract, but descending duodenum (6 cases) and terminal ileum (4 cases) were the commonest sites. Clinical findings varied. All dogs except three presented with chronic illnesses, but only seven showed signs immediately referable to alimentary tract disease. Abnormalities were found at radiographic examination in all cases except one and provided or confirmed the indication for laparotomy. Ten animals were destroyed at the time of surgery, two died during the immediate post-operative period and three were later destroyed because of suspected recurrence. Four dogs are reported well at intervals of between nine months and two years following surgery.  相似文献