I have a swale that feeds my pond. It has a healthy stand of cattails, but it also has a lot of competition: shrub willow, viburnum, green ash seedlings, other woody stuff. If left alone, I think the area would be overgrown with all the woody stuff and shade out the cattails in a few years. The only way I've been able to control the undesirable shrubs is to mow it all down whenever it's dry enough to get a tractor and brush hog in the swale without getting stuck. That's only in August, if at all. The cattails seem to survive, but I don't know if this is the only way to do it. Any other suggestions?