Quantification of sclerotial inoculum of Sclerotinia sclerotiorum in soil samples from soybean fields in Catamarca, Argentina

GONZALEZ, M.A.; REZNIKOV, S.; BLECKWEDEL J.; CLAPS, M. P.; CATALDO, D.M.; GONZÁLEZ, V.; PLOPER, L.D.

PHYTOPATHOLOGY

AMER PHYTOPATHOLOGICAL SOC

Año: 2022

0031-949X

Sclerotinia stem rot, also known as white mold, is an important soybean disease in Argentina, with losses reported up to 55%. It is caused by Sclerotinia sclerotiorum, a soilborne fungus that affects numerous plant species and survives as sclerotia, mainly in the soil. Thus, knowing the amount and viability of the sclerotia, as well as other factors that influence disease development can help select appropriate disease management strategies. The objective of this study was to determine the quantity and viability of sclerotia of S. sclerotiorum in soil samples obtained from six commercial fields located in Los Altos, Catamarca, Argentina, where the disease had been reported in previous years. In each field, four geo-referenced points were sampled and each soil sample corresponded to 0.25 m2(0.50 × 0.50 cm) with 5 cm of depth. The number of sclerotia for each of the six fields was 0, 3, 7, 89, 148 y 179 sclerotia/m2. Sclerotium viability was determined in vitro, with values ranging from 72% to 100%. The two commercial fields that had the highest values of S. sclerotiorum inoculum (148 and 179 sclerotia/m2, respectively) will require effective management strategies to reduce the incidence of this disease.