Parasitism of uredospores of Melampsora larici-populina Kleb. by Cladosporium sp.

The article focuses on the parasitism of uredospores of Melampsora larici-populina Kleb. by Cladosporium species. Conidia of Cladosporium sp. are frequently present in large numbers in collections of uredospores of Melam psora larici-populina made in the field at Canberra in late autumn. The presence of these conidia considerably reduces the viability of the uredospores and consequently infection of leaves of Populus nigra var. italica under controlled conditions. Lysis of germinated and ungerminated uredospores under experimental conditions by the myceliurn of Cladosporium has been demonstrated. The potential for control of leaf rust of poplar by hyperparasitism is discussed.