Target and non-target site mechanisms of fungicide resistance and their implications for the management of crop pathogens

Fungicides are indispensable for high-quality crops, but the rapid emergence and evolution of fungicide resistance have become the most important issues in modern agriculture. Hence, the sustainability and profitability of agricultural production have been challenged due to the limited number of fungicide chemical classes. Resistance to site-specific fungicides has principally been linked to target and non-target site mechanisms. These mechanisms change the structure or expression level, affecting fungicide efficacy and resulting in different and varying resistance levels. This review provides background information about fungicide resistance mechanisms and their implications for developing anti-resistance strategies in plant pathogens. Here, our purpose was to review changes at the target and non-target sites of quinone outside inhibitor (QoI) fungicides, methyl-benzimidazole carbamate (MBC) fungicides, demethylation inhibitor (DMI) fungicides, and succinate dehydrogenase inhibitor (SDHI) fungicides and to evaluate if they may also be associated with a fitness cost on crop pathogen populations. The current knowledge suggests that understanding fungicide resistance mechanisms can facilitate resistance monitoring and assist in developing anti-resistance strategies and new fungicide molecules to help solve this issue. © 2023 Society of Chemical Industry.     

Diagnosis of trichomoniasis in 'virgin' bulls by culture and polymerase chain reaction

The diagnostic test for Tritrichomonas foetus in bulls is microscopic examination of cultured preputial samples. Trichomonads other than T. foetus can be present in a preputial sample. Both a staining technique and a polymerase chain reaction assay were useful in differentiating between T. foetus and another trichomonad observed in samples from virgin bulls.     

Vaccination against foot-and-mouth disease: the implications for Canada

Vaccination of susceptible animals against foot-and-mouth disease (FMD) is a well established strategy for helping to combat the disease. Traditionally, FMD vaccine has been used to control a disease incursion in countries where the disease has been endemic rather than in countries considered free of the disease. In 2001, the use of vaccine was considered but not implemented in the United Kingdom (1), whereas vaccine was used to help to control FMD in The Netherlands (2,3). Canadian contingency plans provide for the use of vaccine; Canada is a member of the North American Foot-and-Mouth Disease Vaccine Bank, which could supply vaccine if needed. This article explains why Canada might use FMD vaccine to combat an outbreak and the factors that are relevant to the disposal of vaccinated animals and their products. It concludes that vaccination is an important mechanism in Canada's preparedness for an outbreak of FMD and that products from vaccinated animals are safe for human consumption.     

Eosinophilic gastroenteritis in a dog

A 9-year-old mixed-breed dog was evaluated for chronic intermittent vomiting, hematemesis, and melena lasting several months. Biopsy specimens obtained during exploratory laparotomy revealed eosinophilic gastroenteritis. Treatment included drug therapy to reduce gastrointestinal inflammation and dietary management to limit antigenic exposure.     

The Occurrence of dsRNA Species in Apparently Healthy and Virus-infected Ribes Cultivars, and Evidence That One Such Species Originates from a Member of the Virus Family Totiviridae

Analysis was made of dsRNA in 37 cultivars and species of Ribes, that were healthy, naturally affected with the virus-like diseases, blackcurrant yellows, blackcurrant infectious variegation, gooseberry veinbanding or blackcurrant reversion, or graft-inoculated with scions from such diseased plants. Various dsRNA species, differing in size (from ca. 2 to 11kbp), number and staining intensity in gels, were detected in some or all assays of all plants, including those held as virus-tested stock. In different plant tissues from individual plants, the dsRNA species were usually similar in size and number but, in some sources, the dsRNA profile from flowers and/or bark differed greatly from the profiles of dsRNA obtained from leaves. No dsRNA species were associated consistently with any of these diseases. A 499kbp cDNA probe was obtained that in Northern blot analysis was specific to a ca. 5kbp dsRNA species present in the blackcurrant cv. Baldwin. It also detected a similarly sized dsRNA species in plants of many other blackcurrant cultivars, but it did not react with a similarly sized dsRNA species in redcurrant and gooseberry tissues. The 156 amino acid sequence encoded by the cDNA was very similar to sequences in the RNA-directed RNA polymerases of virus species in the family Totiviridae, especially Saccharomyces cerevisiae viruses L-1 and L-A. The significance of these findings and the possible origin of these dsRNA species are discussed.     

Searching for veterinary evidence: strategies and resources for locating clinical research.

This article offers information regarding selected veterinary information resources, along with basic search strategies for locating clinical evidence within these resources. No one database provides adequate indexing and abstracting to all literature relevant to the veterinary clinical question. An understanding of a database's syntax and field structure is necessary to formulate a functional search strategy and evaluate the outcome of search results. Flexibility when identifying, selecting, and combining search terms is also required to avoid overlimiting a search.