Lately, the performance of knapsack-type power applicator has been greatly improved due to the introduction of the boom-type blow head and smaller and lighter engine with higher output and low fuel consumption. 
　The reduction of the weight of the whole machinery has been effected by the use of synthetic resin, and the improvements of shock absorbing device together with the improved handling system. As the result, the reliability of this type of machine has been greatly increased. 
　However, there are still a few problems yet to be solved.