Abstract
When the cotton seedlings were artificially inoculated with Rhizoctonia solàni in the Petri dish, the invading hyphae progressed along the slightly depressed seam of the epidermis of root, hypocotyl, and cotyledon. The depression was increased as the fungus hyphae became closely attached.
Root tips were very susceptible to the attack of the fungus. The fungus penetrated the epidermis and branched out into the underlying tissues inter- and intracellularly extending even into the region within the endodermis. Infection in the root also occurred through the natural injuries as new secondary rootlets pushed out from the tap root.
Infection in the hypocotyl occurred mainly by means of ‘infection cushion’, and very rarely was it effected by simple strands of fungus mycelium.
Cotyledons were penetrated. both through the cuticle and the stomatal openings. Both types of infections occurred in about equal frequency in the upper surface of the cotyledon; but stomatal infection predominated in the lower surface.
