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

Abstract

A fungal pathogen, Colletotrichum gloeosporioides (Penz.) Sacc. f. sp. malvae , isolated from anthracnose symptoms of round-leaved mallow ( Malva pusilla Sm.), was shown in greenhouse tests to be host specific to Malva spp. and velvetleaf ( Abutilon theophrasti Medic. # 3 ABUTH), and only with slight attack on hollyhock [ Althaea rosea (L.) Cav. # ALGRO], Malope trifida Cav., and Venice mallow ( Hibiscus trionum L. # 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.