Tall grasses have an advantage over the invasive vine Mikania micrantha: potential control agents.
Mikania micrantha Kunth is an invasive vine in tropical Asia, the Pacific Islands, and northern Australia. It spreads in open fields and over the canopies or crowns of other plants to form a dense year-round blanket that eventually suffocates most plants underneath. To identify grasses that could suppress M. micrantha, we conducted a vast field investigation. Six perennial grass species with tall, slender leaves (Panicum incomtum Trin., Pennisetum purpureum Schum., Saccharum arundinaceum Retz., Microstegium vagans (Nees ex Steud.) A. Camus, Panicum maximum Jacq., and Themeda caudate (Nees) A. Camus) were found to protrude from within or the edges of the vine blanket. These grasses were grown with M. micrantha in a glasshouse pot experiment with three nitrogen (N) levels that represented lower than current, current, and very high N deposition rates, respectively. Increasing N significantly increased M. micrantha biomass. All grasses suppressed the growth of the vine to varying degrees. P. maximum and P. purpureum decreased the biomass of the invasive vine by at least 88.9% and 75.0%, respectively, while P. incomtum caused at least a 63.5% decrease. The other grass species were less effective. This research for the first time revealed that tall and flexible grasses have potential as control agents of M. micrantha.