Picoxystrobin less affected by Asian soybean rust resistance

One of the main pathogens that affects soybean is Asian rust, which is caused by the fungus, Phakopsora pachyrhizi.

″A study we conducted on soybeans highlighted the need for the correct choice and proper application of fungicides, which requires prioritizing strobilurin-based solutions; minimizing the damage caused by Asian rust, target spot and Cercospora leaf blight; supporting the development of the crop and the maintenance of Brazil's leading role in oilseed; and keeping consecutive productivity records,″ said Rogério Rubin, researcher and leader Biology Regional Office at Corteva Agriscience.

The disease can be found in all Brazilian regions, due to the ease of its dissemination by wind, which can cause a fall in productivity of up to 90% in crops.

″Faced with this scenario, measures such as sanitary voids, the correct choice of cultivar and the proper use of fungicides are necessary for maintaining the productive potential of soybeans and reducing productivity losses caused by diseases,″ Rubin added.

In Brazil, the use of fungicides with the same mode of action is common, which can ″accelerate the development of resistant pathogens, making their control difficult and resulting in losses in productivity, as these affect the photosynthetic area of the plants and grain formation,″ he further added.

In the case of Asian soybean rust, damage can reach up to 90%.

″To avoid diseases, fungicides should be used under the 'site-specific' method, which is very efficient in controlling the fungus that causes Asian rust and target spot when used preventively and associated with products’ multi-sites,″ Rubin explained.
 
Among the site-specific fungicides available on the market, the main mechanisms of action (MOA) are demethylation inhibitors (IDM-triazoles), succinate dehydrogenase inhibitors (ISDH-carboxamides) and external quinone inhibitors (IQe-strobilurins).

Rubin stressed that research was recently carried out by various research institutions and led by Corteva Agriscience to evaluate, under field conditions, the control effectiveness of several active fungicidal ingredients applied in isolation.

The studies were conducted to develop methods for controlling Asian rust, target spot and Cercospora leaf blight. The active ingredients analyzed were azoxystrobin (IQe), pyraclostrobin (IQe), trifloxystrobin (IQe), picoxystrobin (IQe), benzovindiflupyr (ISDH), fluxapyroxad (ISDH), bixafem (ISDH) and prothioconazole (IDM).
 
The analysis were carried out over 26 experiments during the 2021/22 harvest and concluded that strobilurins have different levels of control of the evaluated diseases, with a positive emphasis on picoxystrobin, which reached an average control of 51.1% and was superior to the other molecules belonging to this chemical group included in the study, which are trifloxystrobin, pyraclostrobin, and azoxystrobin.

According to the bibliography, picoxystrobin was the active ingredient within strobilurins that was least affected by the F129L mutation, which mostly affects Asian soybean rust.

″Corteva's fungicides based on Picoxystrobin utilize Onmira technology, which eliminates the need to add oil and reduces the risk of washing by rain, with less phytotoxicity for crops,″ Rubin said in conclusion.

(Editing by Leonardo Gottems, reporter for AgroPages)