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Abstract

Influence of temperature, pH and inoculum density on bottom rot on lettuce caused by Rhizoctonia solani.

The soil-borne pathogen Rhizoctonia solani Kuhn occurs throughout the world and has an extremely wide host range. R. solani causes bottom rot disease on lettuce (Lactuca sativa L.). The dominant subgroup seems to be AG 1-IB. The objective of this research was to study the effect of temperature and pH level on mycelial growth of the anastomose group AG 1-IB and to assess the role of temperature conditions and inoculum density on disease development caused by R. solani on lettuce. Optimal hyphal growth was measured over temperature range of 20 to 30 degreesC with a optimum at 25 degreesC and over a pH range of 5 to 8. The disease incidence and development was favoured by higher temperature conditions. Infection on lettuce by R. solani was also observed at lower temperature conditions without effect on plant growth. Temperature conditions of about 15 degreesC during the day reduced plant growth after R. solani infection. Plant growth of infected plants was also influenced by inoculum density of the pathogen and growth inhibition increased with higher inoculum density.



Grosch, R.; Kofoet, A. 2003. Influence of temperature, pH and inoculum density on bottom rot on lettuce caused by Rhizoctonia solani. Zeitschrift für Pflanzenkrankheiten und Pflanzenschutz, 110 (4), 366-378.