We're about to begin our vegetable garden, and we have had some trouble in the past with a nettle that is particularly nasty.
Our plan is to apply glyphosate based herbicide directly to the freshly gut green stalk of this nettle to attempt to kill the rhizomes. The stalks of these nettles is somewhat woody.
Should concentrated glyphosate applied by paintbrush directly to the green stalk kill the rhizomes of hardy nettles?
No, but maybe yes. Glyphosate works 'through the green', so the more leaves which are present, and the more strongly the plant is growing, the better, and all leaves and stems, apart from woody ones, should be treated/sprayed. If you only apply it to a woody stem, its unlikely to do much, though if you're using it neat, it might knock it back, depending on which version of glyphosate based product you're using. Round Up stump and root killer is glyphosate, but much more highly concentrated, so that might work.
Do not, though, get it on the soil if you want to grow edible crops - glyphosate binds to soil particles and has been recorded as still present 200 days later, though the average is 56 days - there is also evidence that carrots grown in ground treated with glyphosate did take it up when they grew.
These are stinging nettles? Another option is to start eating them. Especially in a veggie garden, it is kind of funny to eradicate an edible just to plant a different edible. They really are quite delicious when prepared like spinach. They sell for quite a bit at my local farmer's market. Of course, handle them with gloves and you do need to boil them briefly to neutralize the sting before eating them.
