Puccinia romagnoliana Marie & Sacc. – a Potential Bioherbicide Agent for Biocontrol of Purple Nutsedge (Cyperus rotundus L.) in Mulberry

The ingress, infection process and disease development of Puccinia romagnoliana Marie & Sacc. on purple nutsedge (Cyperus rotundus L.) and its cross-infectivity to an economically important sericultural crop, mulberry (Morus alba L.) were investigated under a scanning electron microscope. The potential of P. romagnoliana as a biocontrol agent was also evaluated for the control of purple nutsedge under greenhouse conditions. Uredinia of P. romagnoliana were paraphysate that bore numerous pedicellate urediniospores, having echinulate spore wall. Urediniospores had 2–3 subequatorial germpores, which gave rise to germtubes. Germtubes were observed to orientate toward stomata and terminated in appressoria, through which infection pegs were formed that penetrated the leaf. Symptoms developed on leaves 10 days after inoculation. P. romagnoliana was highly pathogenic to purple nutsedge, which, when disease was severe, caused death of the shoots and reduced both number and vigour of the tubers. P. romagnoliana did not infect the main commercial crop, mulberry. Thus, the present study demonstrated the potential of P. romagnoliana as a bioherbicide to control the purple nutsedge in mulberry fields.