Fungi Resistance to Multissite Fungicides

Abstract

Multisite fungicides have been used for many years in fruit and vegetable crops worldwide. Cases of the fungi resistance development to these fungicides have been rare. From the 2002 season onwards, with the outbreak of Asian soybean rust in Brazil, caused by Phakopsora pachyrhizi, site-specific fungicides became the main weapon for its control. From 2002 to 2011, penetrant mobile site-specific fungicides were used and until today in double (DMI + QoI) or triple (DMI + QoI + SDHI) co-formulatoons in an area of more than 30 million hectares and with three sprays per area. This resulted, as expected, in the fungus sensitivity reduction, today with cross and multiple resistance to those site-specific fungicides. From the 2011 season in an attempt to recover control that for some chemicals and mixtures reached < 30%, research was started with site-specific + multi-site mixtures, taking as example Phytophthora infestans resistance development to metalaxyl in Europe showinig long-lasting solution found by the addition of multisite mancozeb. It is expected that the effective life of site-specific + multi-site mixtures may be as long in controlling soybean rust as it has been for potato, tomato and grape downy mildews. This review presents the concepts involved in the sensitivity reduction to fungicides. Some fungal species and fungicides involved are listed. Considering the P. pachyrhizi sporulation potential, the great soybean area sprayed and the number of sprays per area mainly with site-specific co-formulations and the reduced area sprayed with multisites, we discuss the need for annual monitoring of P. pachyrhizi sensitivity to the these chemicals.

The genetic basis of adaptation to copper pollution in Drosophila melanogaster

“…Further, because produce sold at the GPO site is grown in Hogback, South Carolina, USA, it is likely that the high levels of copper resistance in the BBM and GPO wild-derived populations are influenced by distinct sources of selection. Copper-containing fungicides are often used to control infections caused by Taphrina deformans in peach trees ( Pecknold, 2015 ; Reis et al, 2021 ), as well as fungi and bacteria that damage wine grapes, olives, and citrus ( Schutte et al, 1997 ; Roca et al, 2007 ; Peña et al, 2018 ), increasing the copper exposure risk for flies collected from the large commercial orchards such as the GPO site. Use of copper-containing pesticides may contribute to elevated levels of copper resistance in the GPO flies, whereas elevated copper resistance in the BBM flies is more likely to be due to historical mining activities.…”

Quantitative plant resistance enhances pathogen adaptation to ecological stresses

“…Site-specific pesticides target the disruption of single biochemical and biological processes of pathogens while site-nonspecific pesticides interfere with several biochemical and biological processes. As a result, resistance to sitespecific pesticides usually develops from sequence alteration in single target genes 41 , while the development of resistance to site-nonspecific pesticides usually involves combinations of mutations in many independent genes distributed across a pathogen genome 42 . Hence, pesticide efficacy and consequent disease mitigation result from complex interactions among pesticide properties and application strategies, pathogens, hosts, and the environments in which the application occurs 43 .…”