Biological control of Aspergillus niger, the cause of Black-rot disease of Allium cepa L. (onion), by Penicillium species

Abstract

The purpose of the study was to explore the control of the onion black rot pathogen, Aspergillus niger, with Penicillium species as biological control agents. Fourteen Penicillium species were isolated from the rhizosphere of different plants. In dual culture agar plate assays, these isolates showed very high antagonistic effects on the growth of A. niger mycelium. Penicillium roqueforti and P. viridicatum greatly inhibited the growth of A. niger by 66% and 60%, respectively, followed by P. bilaii (57%) and P. olsonii (53%). However, it was also observed that the Penicillium species completely overgrew the A. niger colony. The study revealed that some species of the genus Penicillium possessed a high antagonistic effect on the onion black rot pathogen.