Fungicide Resistance In Crop Protection

Francesco Faretra, Department of Plant Protection and Applied Microbiology, University of Bari, Via Amendola 165/A, I-70126 Bari, Italy
E-mail: faretra@agr.uniba.it

Abstract

Fungicide resistance is a challenge in modern crop protection. Most of new fungicides have a very specific, single-site, mode of action, whereas the old chemicals interfer with numerous cell functions in the target pathogen. Specific modes of action have several advantages (enhanced biological activity, usage at low rates, high selectivity for non-target organisms, low environmental impact, etc.), but make more likely the occurrence of acquired resistance in phytopathogenic fungi. In addition to the particular fungicide, the risk of resistance depends also on the genetic and physiological mechanisms underlying resistance, the fitness of resistant strains, the characteristics of the disease (number of cycles per season, size of fungal population in the field, etc.), and growing conditions (i.e., weather, protected crops). Simple methods for monitoring fungicide resistance are crucial for assessing promptly modifications induced in the pathogen’s population by treatment schedules. Crop protection management must implement anti-resistance strategies aiming at reducing as much as possible the selective pressure exerted on fungal populations. This can be achieved adopting integrated disease control, limiting the number of sprays with fungicides at moderate-high risk of resistance, and using mixtures or alternations of fungicides with different mode of actions.