Control of powdery mildew (Erysiphe pisi) of pea (Pisum sativum) with rhizome powder of Zingiber officinale and Acorus calamus

Rhizome powders of two medicinally important plants, Zingiber officinale an d Acorus calamus, were studied for their efficacy against Erysiphe pisi in vitro, under laboratory and field conditions. A. calamus powder at 50 % con centration (w/w) prepared in talc (magnesium silicate) was found to he high ly effective. Appressorium Formation was significantly reduced by 62.6 % 12 h after inoculation. Additionally, a reduction in the colon), growth, numb er of germ tubes and haustoria was observed. Both the powders stopped disea se development in the growth chamber. Foliar treatment with a 50 % (w/w) fo rmulated product from A. calamus and Z. officinale reduced the disease inte nsity From 80 % to 9.2 % and 45.3 %, respectively. Furthermore, number of n odes, pods and seed weight were increased. Rhizome powder treatment was com pared with two commonly used fungicides (Sulfex and Bavistin).