Asian Rust Severity in Soybean Sown in December and February in Mato Grosso State

Erlei Melo Reis,José Otávio Menten,Fernando C Juliatti,Mateus Zanatta,Laércio Zambolim,Luana Maria De Rossi Belufi,Wanderlei Dias Guerra

doi:10.5539/jas.v13n11p127

Abstract

The objective of this work was to assess the effect of December sowing time with February on the Asian soybean rust severity. In on-farm trials two soybean treatments sowing in December (2020) (DSS.) and February (2021) (FSS) were assessed for Asian soybean rust severity in 24 sites, in three regions of Mato Grosso state. The DSS treatment was established in the growers commercial farms and the FSS in a 5 ha area sown specifically for this treatment. The DSS treatment was conducted in 16 sites and the FSS in eigth. For rust control fungicides with efficacy higher than 60% were sprayed consisting of DMIs, QoIs and SDHIs in double or triple mixtures, always added by multisites (chlorothalonil, mancozeb, or copper oxychloride). About eighty soybean leaflets from four plots repetitiond, demarcated at random in each field, were taken in each smpling. In laboratory leaflet severity was appraised and area under disease progress curve (AUDPC) calculated. Related to DSS, the AUDPC overall mean was 174 units and receiving 6.9 fungicide spraying and for FSS 26 units with 4.8 fungicide sprayings. Our results reinforce that the sowing time can be changed from the end of December to February to maintain soybean crop sustainability.

Highlights

The importance of soybean [Glycine max (L.) Merr.] in Mato Grosso, the country largest producer state, is reflected in the cultivated area in the last season, reaching 9.6 million hectares (IMEA, 2021).In Mato Grosso, the main crop disease is Asian soybean rust (ASR) caused by the basidiomycete biotrophic fungus Phakopsora pachyrhizi H
The on farm trials were conducted in the North, South, and weather stations located in Diamanino (West) regions of the state under regional soil and climate differences
The DSS treatment was established in the growers commercial soybean fields and the FSS in a 5 ha area sown especifically for this treatment

Summary

Introduction

The importance of soybean [Glycine max (L.) Merr.] in Mato Grosso, the country largest producer state, is reflected in the cultivated area in the last season, reaching 9.6 million hectares (IMEA, 2021). In Mato Grosso, the main crop disease is Asian soybean rust (ASR) caused by the basidiomycete biotrophic fungus Phakopsora pachyrhizi H. With little published scientific data, damage up to 90% have been cited. Scientifically crop damage can be precisely estimated with the mathematical functions developed by Danelli et al (2015)

Objectives

Methods

Results