What would the world be without Uncle Toms? I will certainly ask a number of people doing extension work if they have found similar results as those mentioned for Cardamine in other plants. These comments have been very enlightening. Nhu's protocol is reasonable and would provide a scientific frame for eventual results. Colleen I am trying your vinegar recipe for seedling weeds as soon as it stops raining. . We have many gravel paths and keeping them clean is a problem. Many thanks.