Thanks for your answers !! Please let me reply to some arguments and please, receive my reply as kind feedback in a discussion about logics and arguments. I am trying to rule out hypotheses and not to start a fight with any one, especially regarding strong convictions - that I share - about the use of chemicals in agriculture !! I need to state it explicitly because written communication is often lacking other aspects of human interactions that would allow smooth exchanges in a friendly atmosphere. 1) Inhibitor secretion and plant competition : Plants killed by roundup stop secreting inhibitors that affect other plants negatively, and seeds can germinate. a) Wouldn't hand weeding give the same result because this mecanism is broken the same way ? b) Wouldn't the release of inhibition bring the germination of any species instead of targeting its effect on Cardamine ? 2) Nitrogen : Roundup breaks down into nitrogen, which causes some fertilizing effect. As for 1), I need to understand by which mechanism Cardamine would be specifically targeted. Additionally, amounts of nitrogen resulting from a diluted amount of spray after months and rains must not be very significant, and one would need to understand how it can have any positive impact on subsequent vegetation. The farmer locally in charge adds some amounts of chemical fertilizer to the fields in spring, this would probably have a big impact in comparison. The phenomenon I have observed with Cardamine is really spectacular : (i) only Cardamine (no other weed), (ii) so densely, and (iii) exclusively at the spots that were treated, that it forces questions. Hand weeding Cardamine is surely to be done rigorously, by the end of winter or early in spring : C. is easy to detect when blooming, but without its tiny white flowers, the smallest individuals are invisible. As soon as seeds pods are formed, the plants should be burned or trashed because seeds may still mature from pods that were nearing the end of their development (which goes really fast), and if not released the usual way (pod explosion), still find their way in the ground and germinate later. I have observed that the specie survives systematic weeding by various strategies, one of which is the size of individuals. You may find plants as small as a few milimeters : invisible, they will produce a few seeds, enough to start a new population. Yes : it is a nasty (or very bright) one. I am very grateful to have read your comments and points of view, please send more. They raise many more questions, but this is the usual process of uncovering the truth - it needs not be interrupted before it brings a lead. Kind regards. *Dr. Christian M. Lachaud, PhD* _________________ http://www.saffron-crocuses.com/