Increased growth responses induced by a nonpathogenic Rhizoctonia solani

A nonpathogenic isolate of Rhizoctonia solani (No. 521, AG-4) induced increased growth in a variety of crops. In field experiments, it was expressed in increases of plant weight, cotton fiber weight, or grain yield. The increases for treated compared with untreated plants were as follows: radish, 13.4–19.8% fresh weight and 28.4–36.0% dry weight; carrot, 30.0–97.6% fresh weight and 55.0–150.5% dry weight; lettuce, 58.4% fresh weight and 61.8% dry weight; cotton, 28.7% fiber weight; wheat, 10.6–25.3% weight per grain and 15.4–36.5% grain yield. For the potato crop, although an increase in leaf, shoot, and tuber weight was induced by R. solani 63–70 days after planting, it was not expressed in yield at harvest time.