[Title: Mosquito Dusting at Winnipeg] [Remark: The RCAF wages war on the deadly wheat rust.] MS of RCAF hangar at Stevenson Field, doors opening and Keystone Puffer airplane being wheeled out by personnel. MS and CU of hopper of plane being filled with sawdust impregnated with creosoil. Shot of engine being started, Puffer taxiing away. MLS of Puffer taking off. Shots of Puffer dusting wheatfield, flying close over camera, dusting pond. PAN over wheatfield. LS of Puffer landing. Low level AERIAL SHOT as plane lands. [Titles interspersed]