Thiocarbamate fungicides: reliable tools in resistance management and future outlook.

Among contact fungicides, dithiocarbamates have remained successful and are used worldwide. These organic sulfur fungicides, viz. mancozeb, maneb, zineb, ziram, thiram, metiram and propineb, have helped growers manage several economically important plant diseases. Their multi-site mode of action and broad-spectrum disease control make them some of the most common partners in mixtures of a number of single-site fungicides as part of resistance management strategies. Indeed, it was the part played by ethylene-bis-dithiocarbamates such as mancozeb in delaying the evolution of phenylamide resistance in several oomycete phytopathogens that laid the groundwork for mixture strategies to become a cornerstone of anti-resistance management in plant disease control. Dithiocarbamates, however, do not have systemic action, are only surface protectants and have to be applied prior to pathogen infection. Dithiocarbamates will likely continue play a key role as reliable resistance management tools to prolong the efficacy of single-site fungicides. The primary metabolite ethylene thiourea produced by some of these fungicides is considered a reproductive and endocrine disrupter in animals. Therefore, dithiocarbamates need to be used at reduced rates or in slow-release formulations. © 2017 Society of Chemical Industry.

Proposal for a unified nomenclature for target-site mutations associated with resistance to fungicides.

Evolved resistance to fungicides is a major problem limiting our ability to control agricultural, medical and veterinary pathogens and is frequently associated with substitutions in the amino acid sequence of the target protein. The convention for describing amino acid substitutions is to cite the wild-type amino acid, the codon number and the new amino acid, using the one-letter amino acid code. It has frequently been observed that orthologous amino acid mutations have been selected in different species by fungicides from the same mode of action class, but the amino acids have different numbers. These differences in numbering arise from the different lengths of the proteins in each species. The purpose of the present paper is to propose a system for unifying the labelling of amino acids in fungicide target proteins. To do this we have produced alignments between fungicide target proteins of relevant species fitted to a well-studied 'archetype' species. Orthologous amino acids in all species are then assigned numerical 'labels' based on the position of the amino acid in the archetype protein. © 2016 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.