REDUCED SEVERITY OF RHIZOCTONIA-SOLANI DISEASE ON WHEAT SEEDLINGS ASSOCIATED WITH THE PRESENCE OF THE EARTHWORM APORRECTODEA-TRAPEZOIDES (LUMBRICIDAE)

The influence of the earthworm Aporrectodea trapezoides on wheat plant s grown in a calcareous sand loam and a red-brown earth soil, artifici ally infested with Rhizoctonia solani, was examined. Presence of the e arthworm A. trapezoides, at a number equivalent to 471 m-2 was associa ted with a significant increase in shoot weight and a reduction in the root disease rating of wheat in both soil types artificially infested with R. solani on wheat chaff. In both soil types, the shoot weight o f wheat grown in the presence of A. trapezoides and R. solani was equi valent to that of wheat grown in the absence of R. solani. One further treatment was applied to each soil type. In the calcareous sand inocu lated with R. solani on wheat chaff, A. trapezoides was as effective a s mechanical soil disturbance in reducing the root disease rating on w heat. In the red brown earth, in which R. solani was introduced via na turally infected roots, the presence of A. trapezoides was associated with a significant increase in shoot weight and a reduction in the roo t disease rating of wheat. These results demonstrate the potential of the earthworm A. trapezoides to reduce the effect of Rhizoctonia root rot on wheat.