Mystery Bramble Taking Over
This is greenbriar, a native vine. It's berries are a good food source to wildlife and it provides cover, so it's not all bad. Obviously it doesn't belong in your lawn but if you plan to have some natural or wild areas, it's good to leave it. It may be spiny or spineless. The berries are blackish or blackish-blue. Yours are much more attractive blue than most.
Greenbriar has an extensive root system as well as small tubers, both of which store energy. You must kill the underground roots and tubers in order to prevent it from regrowing if you cut it down. An herbicide with the ingredient triclopyr will kill this plant. Triclopyr is s systemic, meaning it is absorbed into the system of the plant and goes down and kills the roots. Often, early fall is the best time to spray to get good results. This is not an easy plant to kill and you'll need to be persistent for a while, but it's certainly do-able.
If you have extensive areas of greenbriar, you may want to use a bushhog to cut down the above ground growth. Spray the cut ends immediately after cutting. Then spray any regrowth. The leaves are shiny and make it hard for pesticide to adhere. You may want to mix a "sticker-spreader" product in with the triclopyr herbicide to make it stick to the leaves better.
Thx. We can leave it in the 35' conservation easement, but I suspect it will keep spreading into the area we cleared for a garden. Is there some way to create a barrier so we don't have this stuff climbing up our corn?
Leave a mowing strip you can access between your garden and the easement. Mowing on a regular basis should take care of it for the most part.
You coulf sink the hard black plastic weed barrier (that comes in rolls) about 3-5" wide into the ground. It works well to keep shallow roots out. Greenbriar's deeper roots could be under it however.