Fungicide resistance: facing the challenge - a review

Abstract

Hollomon D.W. (2015): Fungicide resistance: facing the challenge. Plant Protect. Sci., Fungicide resistance continues to generate disease control problems in many crops. Experience amassed over the past fifty years has emphasised the importance of diversity in modes of action in anti-resistance strategies. Because of losses, not only from resistance, but increasingly from environmental and health concerns, the number of modes of action has become dangerously small. This paper considers three challenges facing crop protection in the search for durable disease control systems. Greater understanding of the biochemistry surrounding fungal development and pathogenicity provides opportunities for the discovery and development of novel modes of action, and some recent advances in this area are discussed. To ensure sufficient resources available to take a novel discovery forward to a commercial product, a second challenge facing manufacturers involves early assessment of resistance risk. A third challenge facing researchers, manufacturers and growers requires translation of resistance risk into effective and durable disease control strategies in actual crops. At the core of this challenge is using resistance risk evidence obtained in laboratory and glasshouse studies using individual isolates of target pathogens, to evaluate the fitness cost of resistance in pathogen populations in field crops. Increasingly, management of resistance is seen as the integration of fungicides with non-chemical disease control methods. But success of any Integrated Disease Management (IDM) strategy ultimately depends on the ability of growers to maintain production and profitability.

The origin, versatility and distribution of azole fungicide resistance in the banana black Sigatoka pathogen Pseudocercospora fijiensis

“…Contrary to our expectations, progeny analyses provided strong evidence that DMI resistance in P. fijiensis is solely based on Pfcyp51 modulation and not on other previously reported mechanisms such as increased efflux (Becher & Wirsel 2012;Leroux & Walker 2011). Despite increasing and accumulating data on fungicide resistance in fugal human and plant pathogens (Chowdhary et al 2013;Eddouzi et al 2013;Guzmán et al 2013;Hollomon 2015;Sun et al 2013;Verweij et al 2013;Villani et al 2016), our study is the first genetic analysis to map the underlying genetic factors for reduced DMI efficacy.…”

“…We can exclude the alternative hypothesis that the absence of continuous DMI selective pressure results in the loss of resistance alleles, due to apparent fitness costs of these alleles, which consequently reverts the population back to sensitivity. This effect was shown for Magnaporthe oryzae and Cercospora beticola, but remained unnoticed for many other fungi (Hollomon 2015), and we, therefore, consider it unlikely for P. fijiensis, particularly since we have identified wild-type strains in other nonsprayed areas such as San Carlos in Costa Rica and Bohol in the Philippines (data not show) and in Cameroon, Colombia and Ecuador.…”

“…The latter case supports the fitness costs theory where DMI resistance is accompanied with a fitness penalty, which is rapidly lost in the absence of selective pressure. This phenomena was observed for Magnaporthe oryzae and Cercospora beticola but remained unnoticed for many others fungi (Hollomon 2015).…”

Sensibilidad de aislados de Colletotrichum acutatum obtenidos de fresa a los fungicidas metil tiofanato y azoxystrobin

“…El modo de acción específica y el uso frecuente de estos fungicida implican riesgo para el desarrollo de resistencia en los hongos por lo que deben ser utilizados bajo ciertos principios para un manejo efectivo de la resistencia como son la dosis correcta, número de aplicaciones, mezclas del modo de acción, alternaciones y los tiempos o momentos de aplicación (van den Bosh et al, 2014). Al respecto, es esencial el monitoreo frecuente de la sensibilidad de las poblaciones de hongos y oomycetes en diferentes zonas a nivel regional o nacional a fin de determinar posibles cambios en la distribución de la sensibilidad originados por diferentes mecanismos y en su caso, tomar las medidas correspondientes para retardar, posponer o evitar el desarrollo de resistencia que resulte en pérdidas significativas en los cultivos por la reducción en la vida efectiva del fungicida (van den Bosh et al, 2014;Corio-Costet, 2015), enfoque que debe formar parte de una estrategia de manejo integrado de enfermedades (Hollomon, 2015).…”

Effect of Mancozeb on Mustard (Brassica juncea L.): An In-vitro study

“…Pesticides are extensively used all over the globe to control different pest population and among them fungicides are specially used for control fungal plant pathogens (Mancini & Romanazzi 2013). In the past few, non-target environmental impact and Excessive use of fungicides have caused environmental pollution and development of fungicide resistance in plant pathogens which led to the search for alternative methods (Hollomon 2015). In recent years, crop suffers from many diseases out of them Alternaria blight [Alternaria brassicae (Berk.)…”