Q.What may be killing my vegetables
The picture shows a weed within 6 inches of my garden. It looks diseased and I think poses a threat to my garden. Do you recognize it and what can be done to stop it?
It appears to be a Leaf Curl fungus of some type. I would certainly remove this weed and dispose of. Do not compost this plant material.
The link below discusses Leaf Curl and how to treat it.