Cardamine hirsuta

Christian Lachaud
Tue, 02 Apr 2013 02:38:24 PDT
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*

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