I expect you have larger problems than Glyphosate. It is normally absorbed through the foliage and only minimally through roots. It also kills quickly and degrades rapidly. If you sprayed last year there should be no residual effects this year. While I lived in Sasebo for a couple of years, I do not know the pests of the area. Here we have ground dwelling rodents called voles which tunnel and destroy roots. Moles are carnivores and do no damage other than rooting up plants, they don't eat them.

Thanks farmerdill. I’m currently a bit more north than you were. We have very high pest and disease pressures, I’m guessing from the year-round high humidity and hot summers.

I think we have moles, and the roots are collateral damage. There are tunnels everywhere under the soil. I’m having a hard time catching them. I caught only one so far after a year:

I can’t remember exactly when I sprayed last year, but used it undiluted, because I was trying to kill bamboo and other strong weeds. All four of these affected plants had mole holes exiting right next to the trunk, among other places. There was already a lot of die back before I sprayed anything, presumably from root damage. However, one grape vine is completely dead, and the peach tree is not waking from dormancy despite having buds. This is very strange behavior for mechanical root damage. Seems like a strange coincidence that it coincides with glyso spraying. I thought they may have absorbed it in the fall and been damaged, gone dormant and show the damage in the spring.

That is possible. If the plants were already in decline glyphosate especially at full strength could have been the finishing touch. At recommended strength, I have found very little effect on woody plants and trees and I have fought kudzu, wild grape (Bullous) poison ivy. various sprouting trees etc.

You shouldn't be spraying anything full strength. All the more so if it happens you aren't using something to block spray drift - as is often the case. Roses, for instance seem to be prone to glyphosate damage if you even just talk about spraying around them. However it looks like you have muddy soil, perhaps the peach trees got too wet at some point.

Also if you kill the tops of perennial plants too fast the roots are not destroyed. If you read and follow label directions - as should always be done - you will probably find them telling you to use a dilution in the autumn. Or other time when weed tops are fully developed. And that you can expect to be doing at least a few additional applications later, in order to finish them off.

Thanks again Farmerdill.

The grape is not affected by weedkiller. Consider powdery mildew and something else.

Yes, Mildew and other related problems are a major problem here later in the season, to the point where grapevines must be covered from rain and sprayed. This causes massive leaf loss toward the end of season (And full bunches of grapes that refuse to ripen), but the vines always bounce back better than ever in the spring. The vine in the back is completely dead this year, and the other two are severely retarded.