Influence of leaf blight on yields in geranium Pelargonium graveolens

Experiments were conducted during 1993 and 1994 at Bangalore, India, to est imate the reductions in yield of essential oil caused by leaf blight (Colle totrichum gloeosporioides (Penz.) Sacc.) on three geranium (Pelargonium gra veolens (L.) Herit) clones. Leaf blight resulted in smaller reductions in o il yield in an Algerian-type (Kd) clone than a Reunion-type (Lo) and an Egy ptian-type (Eg) clone. The results indicate that even expensive disease man agement practices can be recommended for management of leaf blight on the L o and Eg clones in regions where leaf blight is prevalent, because increase s in severity of leaf blight may cause considerable economic loss. Such mea sures, however, may not be economically viable for the Kd clone.