knotweed reynoutria dron aerial video shot fallopia japonica sakhalin japanese, invasive and expansive species of

knotweed reynoutria fallopia japonica river dron drone aerial video shot water invasive stream quadcopter view flying fly flight show expansive leaf creek shrub bushes bush biomass growth lush large big plants leaves intruder sachalinensis neophyte japanese asia japan green wild wildflower gatecrasher contamination herbicides nature flower calamity disaster tree wood