Biological control of the annual weed Chenopodium album, with emphasis on the application of Ascochyta caulina as a microbial herbicide

Chenopodium album is a worldwide-distributed plant species growing in disturbed habitats. It is an abundant and very competitive weed in spring-sown crops, particularly if they retain an open structure for a relatively long period. In most crops it is currently controlled by herbicides. In some crops, such as maize, chemical control is difficult, because C. album has become resistant to these herbicides. In other crops, such as sugar beet, the use of herbicides could be reduced considerably if selective control of C. album were possible. Recent experiments using the fungus Ascochyta caulina as a microbial herbicide to control C. album are encouraging (up to 70% control under field conditions). Within the framework of a COST action on 'Biological Control of Weeds in Europe', five countries have cooperated in developing a biological control method for C. album. To integrate the biological control of C. album in existing weed management systems is one of the remaining challenges.