2. Rhizoctonia solani – shoot rot causal agent on grafted vine cuttings during the stratification process

A study was carried out to determine the causal agent of the shoot rotting observed during the stratification of grafted vine cuttings at the Institute of Viticulture and Enology – Pleven. It was found that the described disease symptoms were caused by Rhizoctonia solani fungus, based on the morphology of mycelium colonies and DNA sequencing. The inhibition effect of some fungicides on the mycelia growth of two R. solani isolates derived from naturally infected plant material was studied in vitro.
The radial growth inhibition of EM-10 isolate colonies was demonstrated after treatment with Quadris (250 g/l azoxystrobin) at a dose of 0.075% in vitro. In vivo application of both fungicides, Quadris and Proplant 722 SL (at a dose of 20 ml/m²) inhibited efficiently Rhizoctonia solani infection during the stratification process.Both fungicides did not inhibit the callus formation and did not express unfavorable effect on the graft between the cutting and the rootstock.

Keywords: grafted vine cuttings, stratification, rot, Rhizoctonia solani, fungicides