Biological control of Sclerotinia sclerotiorum on soybean in Catamarca, Argentina

GONZALEZ, M.A.; REZNIKOV, S.; BLECKWEDEL, J.; GONZALEZ, V.; PLOPER, L.D.

Viena

Congreso; World Soybean Research Conference XI (WSRC XI); 2023

Donau Soja Association (Vienna, Austria) - Institute of Field and Vegetable Crops (Novi Sad, Serbia)

Book of Abstracts “Soybean Research for Sustainable Development. p. 458. Sclerotinia stem rot (also known as white mold), caused by Sclerotinia sclerotiorum, is an important soybean disease in Argentina, where yield losses of up to 55% have been reported. This soilborne fungus affects numerous plant species and survives as sclerotia, mainly in the soil. The objective of this study was to evaluate different biological products to reduce the viability of sclerotia of S. sclerotiorum. A total of five treatments were evaluated during the 2020/2021 soybean season in a field trial located in Los Altos, Catamarca province, Argentina. These included an untreated control and four biocontrol products (based on Trichoderma koningiopsis, Trichoderma harzianum, Bacillus subtilis, and a mixture of Bacillus subtilis, Bacillus amyloliquefaciens and Bacillus pumilus) applied in water with a CO2 backpack sprayer, equipped with three hollow cone nozzles (TeeJet model TXA 8001VX) on a handheld boom, calibrated to deliver 150 L ha-1 at a pressure of 294 kPa at the V8 growth stage. Treatments were arranged in a randomized complete block design with four replications. Plots consisted of four 6-m rows, spaced 0.5 m apart (12 m2) with plastic trays (25x17x4 cm) placed between rows. Each plastic tray contained 2 kg of sand in which 25 sclerotia with 99% of viability were placed on the surface. The plastic trays were removed 20 days after the application and the viability of the sclerotia analyzed in the laboratory on potato-dextrose-agar medium. The viability of the sclerotia ranged from 19% (Trichoderma koningiopsis treatment) to 25% (Bacillus subtilis treatment), whereas the untreated control had 99% viability. Sclerotia were colonized by the biological products with values from 69% (Bacillus subtilis) to 80% (Trichoderma koningiopsis). These results indicate that biological products are effective in reducing the viability of sclerotia and thus could be an effective management strategy to reduce the impact of the initial inoculum of S. sclerotiorum.