The Potential of an Endemic Fungus,Colletotrichum gloeosporioides, for Biological Control of Round-Leaved Mallow (Malva pusilla) and Velvetleaf (Abutilon theophrasti)

A fungal pathogen,Colletotrichum gloeosporioides(Penz.) Sacc. f. sp.malvae, isolated from anthracnose symptoms of round-leaved mallow (Malva pusillaSm.), was shown in greenhouse tests to be host specific toMalvaspp. and velvetleaf (Abutilon theophrastiMedic. #3ABUTH), and only with slight attack on hollyhock [Althaea rosea(L.) Cav. # ALGRO],Malope trifidaCav., and Venice mallow (Hibiscus trionumL. # HIBTR). Round-leaved mallow plants inoculated with a spore suspension of the fungus were killed after 17 to 20 days. It was less pathogenic on velvetleaf with 60 to 70% attack. The fungus can readily be cultured and field tests from 1982 to 1987 resulted in excellent control of round-leaved mallow under natural conditions. Therefore, it has good potential for biological control of round-leaved mallow in field crops.