Governing Principles Can Guide Fungicide-Resistance Management Tactics

Abstract

Fungicide-resistance management would be more effective if principles governing the selection of resistant strains could be determined and validated. Such principles could then be used to predict whether a proposed change to a fungicide application program would decrease selection for resistant strains. In this review, we assess a governing principle that appears to have good predictive power. The principle states that reducing the product of the selection coefficient (defined as the difference between the per capita rate of increase of the sensitive and resistant strains) and the exposure time of the pathogen to the fungicide reduces the selection for resistance. We show that observations as well as modeling studies agree with the predicted effect (i.e., that a specific change to a fungicide program increased or decreased selection or was broadly neutral in its effect on selection) in 84% of the cases and that only 5% of the experimental results contradict predictions. We argue that the selection coefficient and exposure time principle can guide the development of resistance management tactics.

Effect of Laboratory Synthesized Cu-Chitosan Nanocomposites on Control of PFSR Disease of Maize caused by Fusarium verticillioids

“…The usage of highly toxic chemicals for control of plant diseases has increased exponentially to achieve higher productivity in general and maize in particular. The excessive use of toxic chemicals has lead to the deposition of nondegradable chemicals in environment which causes health hazards (Akoto et al, 2014) and also induces resistance in target pathogens (Bosch et al, 2014). These issues exert pressure to initiate alternative strategy to decrease dependence on pesticides in crop protection (Rai and Ingle, 2012).…”

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).…”

“…En cítricos Mondal et al (2005) reportaron líneas base (previo al uso de their frequent use pose a risk because they cause the pathogen to develop resistance. Therefore, they must be utilized following certain guidelines for effectively managing resistance (the correct dose, number of applications, mixing fungicides that have a different mode of action, alternation and application timing) (van den Bosh et al, 2014). It is also essential to frequently monitor the sensitivity of fungal and oomycete populations in different areas at the regional or national level so as to detect changes in the distribution of sensitivity caused by different mechanisms.…”

“…It is also essential to frequently monitor the sensitivity of fungal and oomycete populations in different areas at the regional or national level so as to detect changes in the distribution of sensitivity caused by different mechanisms. If necessary, implement appropriate measures to delay, postpone or prevent the development of resistance, which could cause significant crop losses due to the reduction of the fungicides' effective life (van den Bosh et al, 2014;Corio-Costet, 2015). This approach must be included in all integrated disease management strategies (Hollomon, 2015).…”

Chalcones to control Alternaria alternata in murcott tangor fruits

“…As the infected fruits are undervalued (VICENT et al 2007), fungicides are usually employed to reduce the severity of this disease under field conditions (SOLEL; OREN; KIMCHI, 1997). In growing areas with high humidity and temperature, about 15 applications of fungicides are required per year to control this disease (TIMMER et al, 2003;BOSCH;BERG;PAVELEY, 2014), thus contaminating humans and the environment with substances of high toxicity (CARVALHO et al, 2007).…”