Control of Microdochium albescens in pre-germinated and dryland rice seeds

Evandro Zacca Ferreira,Flávio Chupel Martins,Ricardo Trezzi Casa,Juliano Berghetti,Marília Michalski De Pieri,Bruno Tabarelli Scheidt

doi:10.1590/0103-8478cr20200639

Evandro Zacca Ferreira, Flávio Chupel Martins + Show 4 more

Open Access

https://doi.org/10.1590/0103-8478cr20200639

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Abstract

ABSTRACT: The fungus Microdochium albescens can interfere in the germination of seeds and in the death of rice seedlings; however, there is not technical indication for its control by seed treatment. This research evaluated the efficiency of fungicides in the treatment of pre-germinated and dryland rice seeds in the control of M. albescens. Seeds of the cultivars, Epagri 109, SCS116 Satoru, SCS121 CL and SCS122 Miura were treated with the following fungicides (g a.i./100 kg of seeds): fluazinam + thiophanate methyl (9.45 + 63), pyraclostrobin + thiophanate methyl (5 + 45), carboxin + thiram (60 + 60), metalaxyl-M + thiabendazole + fludioxonil (3 + 22.5 + 3.75), carbendazim + thiram (45 + 105), carbendazim (45). Seeds without fungicide treatment constituted the control. The treated seeds were sown in potato-sucrose-agar (PSA) culture medium and incubated at 25 ± 2 °C and photoperiod of 12 hours for 14 days. Treated seeds were also submitted to the germination test. Fluazinam + thiophanate methyl and metalaxyl-M + thiabendazole + fludioxonil showed greater control of M. albescens, not differing statistically between them, in the five cultivars and in the two cultivation systems. The tested fungicides provided seed germination above 90% in the four cultivars.

Highlights

Leaf scald, caused by the fungus Microdochium albescens Thüm
Health tests for irrigated rice seeds from Santa Catarina crops, performed at the Phytopathology Laboratory of the Universitdade do Estado de Santa Catarina in the 2015/16, 2016/17 and 2017/18
Seven seed treatments were evaluated for each cultivar, six fungicides and one control, where: T1-fluazinam + thiophanate methyl (9.45 + 63 g a.i) (Certeza®); T2-pyraclostrobin + thiophanate methyl (5 + 45 g a.i) (Standak Top®); T3- carboxin + thiram (60 + 60 g a.i) (Vitavax Thiram®); T4- metalaxyl-M + thiabendazole + fludioxonil (3 + 22.5 + 3.75 g a.i) (Maxim Advanced®); T5- carbendazim + thiram (45 + 105 g a.i) (Derosal Plus®); T6- carbendazim (45 g a.i) (Carbendazim Nortox®) in doses of commercial producer per 100 kg of seed-1 and T7- control, untreated

Summary

Introduction

Leaf scald, caused by the fungus Microdochium albescens Thüm (Syn. Microdochium oryzae Hashioka & Yokogi; Gerlachia oryzae Hashioka & Yokogi), has been reported in all rice producing regions in the world (FARR et al, 2008). Seeds are considered a source of primary inoculum (OU, 1985; WEBSTER & GUNNELL, 1992), and the transmission of the fungus in dryland cultivation occurs through infected seeds causing discoloration in the seedlings (FILIPPE et al, 2005; GUTIÉRREZ, 2008). Leaf scald reduces the number, weight and physiological quality of seeds (MOURA et al, 2014), causing up to 30% damage to yield (THOMAS, 1984). Companies seek to meet the standards of seed commercialization; and adopted measures for quality control using physiological tests, such as germination and vigor tests, and alternatives for maintaining quality through seed treatment.

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