The use of phosphates in forestry

Abstract

Phosphite preparations are now an important alternative in plant protection against new, invasive pathogens of the genus Phytophthora and/or Pythium. It is crucial to intervene when alien, invasive oomycetes are carried to plantations or forest stands and attack fine roots via zoospores. The aim of this paper was to demonstrate the possibility of phosphite application to induce resistance to tree pathogens. Phosphate-based fertilizers have been used successfully in nurseries, where application is relatively easy by means of foliar sprays. the traditional fungicides, which are effective in combating fungi, however, fail to control oomycetes. Instead, they mask the disease, which, in turn, causes serious damage to seedlings after they have been planted in a suitable environment. Moreover, the number of effective fungicides available for forest plant protection has continued to decrease in the last decade. The effectiveness of the chemicals is reduced due to their frequent use and their similarity in terms of the active compound or the mechanism of action. Given the low diversity of active compounds, it is necessary to monitor the development of resistance of pathogens to fungicides by means of molecular biology (sequencing and quantitative PCR). Minimising the undesired side effects of chemicals on both, mycorrhizal fungi and pathogens can be achieved by strict adherence to rigorous security measures and, where possible, frequently changing the active compounds to alternatives such as phosphites. The significance of phosphate and phosphite uptake by trees is still a matter of debate, especially under field conditions. Nevertheless, phosphites are environmentally friendly compounds, which constitute an alternative or complement to the traditional chemicals (in accordance with the Directive on Integrated Plant management).

Los fosfitos como alternativa para el manejo de problemas fitopatológicos

“…The phosphite ion is easily transported in plants via xylem and phloem (McDonald et al, 2001;Tkaczyk et al, 2016), so it has been used in foliar applications (Rebollar-Alviter et al, 2010; Fue a principios de 1930 cuando se concluyó que los fosfitos no eran fuente eficiente de fosforo para la nutrición de las plantas y 40 años después, regresó al mercado de los agroquímicos como alternativa para el manejo de enfermedades, cuando la compañía Francesa Rhône-Poulenc ofreció el ingrediente activo fosetil-aluminio para el control de mildius y enfermedades causadas por el género Phytophthora (Tkaczyk et al, 2016;Achary et al, 2017). Los fosfitos, como alternativa para el control de organismos fitoparásitos, han sido estudiados ampliamente y su eficacia se ha probado contra protozoarios, oomycetes, hongos, bacterias y nematodos fitoparásitos (Cuadro 1); adicionalmente, se ha comprobado su eficacia como bioestimulador (Gómez-Merino y Trejo-Téllez, 2015), para disminuir los daños por malezas (Manna et al, 2016;Achary et al, 2017) y radiación UV-B (Oyarburo et al, 2015).…”

“…Debido a su similitud estructural, los fosfitos son considerados como análogos de los fosfatos, sin embargo, el uso de los fosfitos como fungicidas y bioestimulantes para el control de patógenos de plantas es ampliamente aceptado, pero su utilización como fuente de fós-foro en la nutrición de plantas es actualmente debatida (Borza et al, 2014;Gómez-Merino y TrejoTéllez, 2015;Alexandersson et al, 2016;Manna et al, 2016). Además, esa diferencia da a los fosfitos una mayor movilidad en el suelo y en los tejidos de las plantas, así como una mayor capacidad para penetrar a través de hojas, tallos y raíces (Tkaczyk et al, 2016).…”

“…No obstante, este proceso es muy lento, y puede tomar hasta cuatro meses para completarse, lo que resulta impráctico para la agricultura (McDonald et al, 2001;Lovatt y Mikkelsen, 2006). phosphites a greater mobility in soil and plant tissues, as well as a greater capacity to penetrate through leaves, stems and roots (Tkaczyk et al, 2016).…”

“…However, 40 years later, phosphites returned to the agrochemicals market as an alternative for controlling plant diseases, when the French company Rhône-Poulenc offered the active ingredient fosetyl-aluminum to control mildews and diseases caused the Phytophthora genus (Tkaczyk et al, 2016;Achary et al, 2017). Phosphites, as an alternative for controlling phytoparasite organisms, have been extensively studied and proven to be effective against protozoa, oomycetes, fungi, bacteria and phytoparasite nematodes (Table 1), as well as biostimulators (Gómez-Merino and TrejoTéllez, 2015) that reduce damages caused by weeds (Manna et al, 2016;Achary et al, 2017) and UV-B radiation (Oyarburo et al, 2015).…”

The influence of phosphite treatments on oak leaves and damage caused by powdery mildew Erysiphe alphitoides

“…Phosphites were used successfully to stop the progress of Phytophthora in Australia (Hardy et al2017). Some records of positive influence of phosphites on forest tree species in nursery, including the reduction of oak mildew infestation, were found in the past (Tkaczyk et al 2014;Okorski et al 2014).…”