Temperature and Potting Medium Effects on Growth of Boston Fern Infected with Rhizoctonia solani

Factorial experiments, including three potting media, two potting medium temperatures, and two air temperatures were used to evaluate growth of Nephrolepis exaltata ‘Fluffy Ruffle’ (Boston fern) infected with Rhizoctonia solani (the causal agent of aerial blight). Potting medium mixtures of sphagnum peat-sand, sphagnum peat-pine bark, and sphagnum peat-vermiculite-perlite did not affect severity (percentage of foliar infection) in four of five tests. Plant quality was highest for plants grown in peat-vermiculite-perlite in two of four tests. Potting medium temperature of 32°C reduced percentage of foliar infection in four of five tests, and plant quality in three of four tests. Fresh weights of shoots or roots were not affected consistently by potting medium temperature at 32°. Air temperatures ranging from 35° to 38° were favorable for disease development, with reduced development at temperatures above 35°. In vitro radial growth of R. solani isolates was optimal at ≈30° with a statistically significant reduction at 35°.