Soil properties related to suppression of Rhizoctonia solani on tobacco fields from Northwest Argentina

HARRIES, E.; BERRUEZO, L.A.; GALVÁN, M.Z.; RAJAL, V.B.; MERCADO CÁRDENAS, G.E.

PLANT PATHOLOGY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2019 vol. 69 p. 77 - 86

0032-0862

Biotic and abiotic factors from soils have been implicated in the diseasesuppressionof Rhizoctonia solani. This study included aEucalyptus twig baiting assay, disease index and qPCR quantification of R. solani,and physicochemical analysis of 10 tobacco soils from five different locations (V: Vaqueros, C: Cerrillos, R: Rosario de Lerma, SA: San Agustín, CH: Chicoana) in thenorthwest of Argentina. Levels of Rhizoctonia soil inoculum quantified by baiting assay and qPCRwere positively correlated. However,there was no correlation with root rot disease index intobacco fields. Soils from V1, SA2 and CH2 fields,which reduced root rot disease on tobacco plants,weresuppressive to R. solani infection. High clay, pH, organic matter content and physical stability in tobacco soils were the main physicochemical properties that limited Rhizoctonia development. Interestingly, growth of R. solani subgroups AG4-HGIand AG4-HGIII was highly suppressed in V1 and CH2 fields, and in SA2 fields, respectively. Undisturbed soil from a local forested mountain also resulted in reduction of growth ofAG4-HGIII and AG4-HGI, while AG2-1 was less affected, suggesting that high soil organic matter contributed to suppression of R. solani. Soils highly suppressive of R. solani had significantly differentpopulations of culturable bacteria,Pseudomonasand fungi, but populations of actinobacteria and Trichoderma spp.did not differ. These different populations may be involved in the inhibition of fungal growth.The results demonstrate dthat physicochemical and biological properties of soil suppressive to R. solani could act as an alternativefor controlling Rhizoctoniadiseases on tobacco.