Wouldn't girddling the tree and spraying pathway into the cut also kill it. Pathway is available in small quantities and easily found.
I'm have no credentials in this area. But, in recent years, I've taken a number of silviculture (mostly forestry) classes and other agriculturally related classes. I'm fairly familiar with what is out there.
First, there are an incredible number of different types of willows in the US. Many are not native. Not all respond the same way.
I'm not sure that Pathway will control most willow. I'll do a little more digging and post more later.
As for imazypr (aka Arsenal, Assault, Chopper), it is extremely effective. It will take care of your willows. Unfortunately, it is also extremely deadly to more than just the plants you are trying to eliminate. If you choose to use it, use it very sparingly and very carefully. It is deadly to everything -- trees, plants, animals,
especially fish, and the soil. In the soil, it spreads very quickly over a wide range, and to extreme depths. It will be very toxic to critters that might happen to lick or chew the stump you apply it to. It can stay in this active state for more than a year.
I'd suggest you take a cutting of what you have to your state Extension Service office. Explain your situation and its location related to your pond.
I'm currently trying to figure out what I'm going to do with a large willow (about 10" dbh) at the bottom of my dam that has partially fallen over after several major storms. I plan on cutting it in the next couple of days. I'm just not sure what I'm going to do after that.
More suggestions and ideas would be greatly appreciated by me.
Ken
