[cmpb]

>We removed 1.5 million plants at 21 events in seven state parks this year.

I have been involved in Ardisia and Tallow removal efforts here in the US south. When the infestation is this bad, you're not going to solve it with mechanical methods, no matter how hard you try and how many people you have doing it. Chemicals can definitely help, but they often have unexpected detrimental side effects to other native plants and animals (though sometimes they have unexpected beneficial effects on other native plants - I've seen rare prairie natives pop up in Louisiana after Triclopyr killed off overcrowded baccaris under power lines).

I wonder, could we develop a "gene drive" for plants?