Synergism in fungicide mixtures againstPseudoperonospora Cubensis

Mixtures of cymoxanil with mancozeb (Mancur) or with mancozeb plus oxadixyl (Pulsan, Sandocur-M) were effective in controlling either metalaxyl-sensitive (MS) or -resistant (MR) isolates ofPseudoperonospora cubensis on cucumbers (cv. ‘Elem’) in growth chambers. Metalaxyl+mancozeb (Ridomil-MZ) and oxadixyl+mancozeb (SAN-518) mixtures were effective against the metalaxyl-sensitive but less so against the metalaxyl-resistant isolate. Fungicide mixtures were far more effective in controlling either the sensitive or the resistant isolates than were the individual components applied alone, thereby representing significant levels of synergistic interactions. Increased efficacy of mixtures relative to their combined components (synergy factor) was calculated by the Wadley method. Mixtures containing cymoxanil showed high synergy factors against the resistant isolate, whereas Ridomil-MZ and SAN-518 did not evince this phenomenon. We concluded that cymoxanil mixtures might be suitable for the control of downy mildew incited by a metalaxyl-resistant isolate ofP. cubensis.     

Inactivation of sclerotia of Rhizoctonia solani on potato tubers by Verticillium biguttatum,a soil-borne mycoparasite

Experiments in the laboratory and on farms with potato tubers in storage are described in which sclerotia ofRhizoctonia solani were inactivated after inoculation of infected tubers with a suspension of conidia and hyphal fragments ofVerticillium biguttatum. Sclerotia on freshly harvested tubers can be killed in a period of six to eight weeks, provided that (1) a direct contact between sclerotia and conidia ofV. biguttatum is obtained, (2) the temperature during the storage period is at least 15 °C, but preferably closer to 20 °C during the first weeks, and (3) the relative humidity of the air between the tubers is at least 99%. Seed tubers are only certified as export quality if the infection withR. solani, visible as sclerotia on the tubers, is assessed as below a specified incidence. To restore the economical value of tubers with many sclerotia, living sclerotia can be inactivated byV. biguttatum. However, also dead sclerotia have to be removed, as dead and living sclerotia cannot be distinguished visually by inspectors. A satisfactory way to remove dead sclerotia from tubers has not yet been found.     

Noninfectious nonerosive arthritis in two dogs

Two cases of noninfectious, nonerosive arthritis are presented. The diagnostic features, clinical course and treatment are reviewed. Potential etiologies are discussed in the light of relatively little current material on this subject in the veterinary literature.     

A bacteriological investigation of subcutaneous abscesses in cats

Ten out of eleven subcutaneous abscesses in cats harboured anaerobic bacteria. Seven of the ten abscesses contained a mixture of obligate anaerobes and facultative anaerobes or microaerophilic bacteria. All of the anaerobic isolates were sensitive to the antibiotic metronidazole, but were resistant to streptomycin. Three isolates from one abscess were resistant to penicillin and ampicillin. Clinical resolution of subcutaneous abscesses was poor when procaine penicillin was used alone as treatment.