Phosphite uptake and distribution in potato tubers following foliar and postharvest applications of phosphite-based fungicides for late blight control

Abstract

Foliar and postharvest applications of phosphite (Phi)-based fungicides are used to control the oomycete Phytophthora infestans which is responsible for the occurrence of late blight in potatoes. Optimisation of the usage of Phi-based fungicides for disease control during the growing season and in subsequent storage can lead to improved potato production and processing quality. In order to assess the efficiency of Phi translocation to tubers, following foliar and postharvest treatments of potato crops with the Phi-based fungicides, the amount of Phi in tubers was determined by a high-performance ion chromatography method. The quantity of Phi found in tubers increased with the total amount of Phi-based fungicides applied during the growing season. Foliar applications of Phi resulted in an uneven distribution of Phi in the three tuber regions analysed, with high concentrations being identified in the tuber cortex (32.5-166.4 μg g −1 fresh tissue) and medulla regions followed by the skin area. Postharvest treatment of tubers led to a different distribution of Phi, with the highest concentrations of Phi found in the skin (411.0-876.6 μg g −1 fresh tissue) followed by the cortex and medulla regions. As foliar treatments are essential to protect the aerial parts of the plants during the growth season, the best disease management practices of tubers should include the postharvest treatment in addition to foliar applications. The use of both types of treatments ensures that concentrations of Phi in excess of 100 μg g −1 fresh tissue are present in tuber skin and cortex areas; such concentrations are needed to suppress the growth of P. infestans on tubers during storage.

Botanicals and Phosphonate Show Potential to Replace Copper for Control of Potato Late Blight

“…Residues of phosphite (PO 3 3− ) were analysed in potato tubers from the field experiments in 2012 and 2013. As observed in another study [ 33 ], the phosphite concentrations in the tubers were directly proportional to the number of applications and the amount of applied Ph. With eight applications of 3.0 L/ha Ph, 47 mg/kg PO 3 3− were detected in the analysed potato tubers.…”

“…Regardless of this undesirable property of phosphite based products, increasing attention to integrate them in PLB control strategies was observed in conventional agriculture, for example, in developing countries [ 30 ] as well as in Sweden [ 34 ] and in Canada [ 33 ]. It was underlined that due to their excellent environmental profile, the usage of such products will reduce the environmental impact of pesticides applied to the potato crop [ 35 ].…”

“…Together with the favourable environmental profile, the complex mode of action of phosphonates is another reason to suggest the use of such products. Indeed, with the increasing occurrence of resistance to systemic fungicides based on phenylamides, the usage of phosphanates became more attractive [ 30 , 33 ]. Another interesting feature of foliar phosphonate applications consists in the suppression of tuber infections [ 37 ].…”

Los fosfitos como alternativa para el manejo de problemas fitopatológicos

“…El ion fosfito es fácilmente transportado en las plantas vía xilema y floema (McDonald et al, 2001;Tkaczyk et al, 2016), por lo que se ha utilizado en aplicación foliar (Rebollar-Alviter et al, 2010;Silva et al, 2011;Pagani et al, 2014;Yáñez et al, 2014;Liljeroth et al, 2016;Borza et al, 2017), baño a la raíz y cuello de la planta (Oka et al, 2007;Akinsanmi y Dreth, 2013), inyección al tronco (Bock et al, 2012;Akinsanmi y Drenth, 2013: Aćimović et al, 2015Aćimović et al, 2016), a través de riego por goteo mezclado en la solución nutritiva en hidroponía (Förster et al, 1998), tratamiento a semilla (Abbasi y Lazarovits 2006; Lobato et al, 2008), aplicación aérea en bajo volumen ) o como tratamiento en inmersión de semillas y frutos (Anderson et al, 2012;Cerioni et al, 2013, Borin et al, 2017Pagani et al, 2014;Yáñez et al, 2014;Liljeroth et al, 2016;Borza et al, 2017), drench of plants root and neck (Oka et al, 2007;Akinsanmi and Dreth, 2013), trunk injection (Bock et al, 2012;Akinsanmi andDrenth, 2013: Aćimović et al, 2015;Aćimović et al, 2016) through drip irrigation mixed in a nutrient solution in hydroponics (Förster et al, 1998), seed treatments (Abbasi and Lazarovits 2006; Lobato et al, 2008), low-volume aerial applications or as a treatment in seed and fruits immersion (Anderson et al, 2012;Cerioni et al, 2013, Bor...…”

Effect of phosphites on the content of total phenols and chlorogenic acid in peach-Monilinia fructicola pathosystem

“…Phosphites are not-phytotoxic compounds that have a high fungicidal activity (14) (15) . Their mode of action may be direct or indirect, through the activation of plant defense mechanisms by phytoalexin production (14)(16)(17) (18) .…”