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Approaches to the biological control of weeds in arable crops and integration of biological weed control with other methods of weed management are broadly discussed. Various types of integrative approaches to biological control of weeds in crops have been studied within the framework of a concerted European Research Programme (COST‐816). During the period 1994–99, some 25 institutions from 16 countries have concentrated on five target weed complexes. Some major scientific achievements of COST‐816 are: (i) combination of the pathogen Ascochyta caulina with an isolated phytotoxin produced by this fungus to control Chenopodium album in maize and sugar beet; (ii) the elaboration and preliminary field application of a system management approach using the weed:pathogen system Senecio vulgaris:Puccinia lagenophorae to reduce the competitiveness of the weed by inducing and stimulating a disease epidemic; (iii) combination of underseeded green cover with the application of spores of Stagonospora convolvuli to control Convolvulus species in maize; (iv) assessment of the response of different provenances of Amaranthus spp. to infection by Alternaria alternata and Trematophoma lignicola, the development of formulation and delivery techniques and a field survey of native insect species to control Amaranthus spp. in sugar beet and maize; (v) isolation of strains of different Fusarium spp. that infect all the economically important Orobanche spp. and development of novel, storable formulations using mycelia from liquid culture. Although no practical control has yet been reached for any of the five target weeds, potential solutions have been clearly identified. Two major routes may be followed in future work. The first is a technological approach focusing on a single, highly destructive disease cycle of the control agent and optimizing the efficacy and specificity of the agent. The second is an ecological approach based on a better understanding of the interactions among the crop, the weed, the natural antagonist and the environment, which must be managed in order to maximize the spread and impact of an indigenous antagonist on the weed. 相似文献
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C. Kempenaar P. J. F. M. Horsten P. C. Scheepens 《European journal of plant pathology / European Foundation for Plant Pathology》1996,102(2):143-153
Ascochyta caulina is considered a potential mycoherbicide againstChenopodium album. Disease development ofC. album plants and plants of 14 other species after application of pycnidiospores ofA. caulina was studied in climate chamber experiments. The experiments were carried out to analyse disease development with time, and to recognize factors that may limit disease development. Two time courses of necrosis ofC. album plants were observed, (1) an increase of necrosis followed by a decline, and (2) an increase of necrosis up to completion with subsequent plant death. Courses of necrosis with time could be described by a non-monotonic, critically damped model when plants survived infection and by a monomolecular model when plants died from infection. Disease development was influenced by interactions between wetness period, density of the spore suspension applied, plant development stage at the time of spore application, and temperature. Disease was favoured by a long wetness period, a high number of spores applied, an early plant development stage at the time of spore application, and temperatures of 18 C and higher. Disease development was limited to plant species of the generaChenopodium, Atriplex andSpinacia with differences between the species. Pathogenicity differed significantly between threeA. caulina isolates tested. Variation in resistance between four source populations ofC. album was small. Prospects forA. caulina as a mycoherbicide are discussed. 相似文献
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Scheepens ET Peeters ME L'eplattenier HF Kirpensteijn J 《The Journal of small animal practice》2006,47(12):721-726
OBJECTIVES: Canine bite wounds may cause severe underlying tissue trauma even with no clinically evident puncture wounds. In order to assess the ability of pre-operative diagnostic parameters to predict the extent of internal damage inflicted by a thoracic bite wound, the clinical, radiological and surgical data of 45 dogs that sustained thoracic bite trauma were recorded. METHODS: Clinical, radiographic and surgical parameters from 45 dogs of various breeds with thoracic bite trauma, were analysed (P<0.05). All dogs were treated according to a previously described protocol and had exploratory surgery including a thoracotomy. RESULTS: Mainly small-breed dogs were traumatised. Clinical and radiological data were suggestive of internal trauma but not reliable as accurate indicators for internal lesions. Only radiological evidence of lung contusion was significantly associated with the presence of surgically confirmed lung contusion (P=0.006). Dogs with postoperative wound complications had a significantly higher risk of dying than those without complications (P=0.04). CLINICAL SIGNIFICANCE: This study concludes that according to protocol an optimal management of thoracic bite wounds in small dogs includes surgical exploration of the wound and the thoracic cavity in the presence of flail or pseudo-flail chest, fractured ribs, radiological evidence of lung contusion, pneumothorax or any combination of these. 相似文献
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P. C. Scheepens A. Hoogerbrugge 《European journal of plant pathology / European Foundation for Plant Pathology》1991,97(4):245-250
Aim was to clarify the rust fungusPuccinia canaliculata for release in a new environment where it may be utilized as a microbial herbicide. A strain of the rust was introduced from the USA into the Netherlands and kept in quarantaine. The susceptibility ofCyperus esculentus and several other species of the Cyperaceae was tested.
C. esculentus leptostachyus from five locations was susceptible toP. canaliculata. C. esculentus of a yet unidentified biotype from two locations was moderately susceptible (fewer and smaller pustules than on leptostachyus), whereas plants of the same biotype from a third location were resistant to the rust.C. esculentus esculentus (from one location) andC. esculentus sativus (a crop) were also resistant to the rust.
C. albostriatus, C. alternifolius, C. flavescens, C. rotundus, Carex hirta, Eleocharis palustris, andScirpus maritimus were resistant toP. canaliculata. OnCyperus fuscus, P. canaliculata produced very small urediniosori (less then 1 mm in diameter); the sori were surrounded by a zone of necrotic plant tissue.From the observations onC. fuscus we concluded that the (potential) host range ofP. canaliculata is wider than we originally expected. For safety reasons, it was decided not to release it in the Netherlands. 相似文献
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A neutered female chow chow aged six years and five months was evaluated for dysuria. An initial diagnosis of bladder distension and atony was made following physical, ultrasonographic and radiographic examinations. The problems did not resolve with medical management and exploratory surgery revealed a large bladder diverticulum. This report describes the radiographic findings and surgical repair of the acquired bladder diverticulum. The literature available on this condition is also reviewed. 相似文献
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