The effect of three resistance inducers, i.e. chitosan, citrien and potassien were studied under both greenhouse (2009/2010) and field condition in 2010/2011 and 2011/2012 growing seasons to control powdery mildew disease caused by Sphearotheca fuliginea in chamomile (Matricaria chamomilla).Results showed that all used inducers had decreased disease severity compared to non-treated control. In this respect, chitosan showed the highest effect on decreasing disease severity followed by citrien. Meanwhile, potassien gave the lowest effect. The decrease in disease severity of powdery mildew was positively expressed by an increase in crop parameters, i.e numbers, inflorescences weights, fresh, dry weights of plants and the principal components of chamomile essential oil.