[RWG] Use the chemical effects of native plants, against the weeds

[Craig Dremann - Redwood City Seed Company]

Dear Wayne and All,

Sorry I missed your question a week ago>>>If I understand Dremann
correctly, he does not know "the id of the active herbicide chemicals in
the plants," but if this is true, how does on "measure the chemical
effects of one plant against another?"

If you get a chance to read Dr. Lius papers in the Journal of Chemical
Ecology, he has several ways to measure the allelochemical herbicide
strengths.   Of interest to us weed managers and restorationists in the
arid West, is Dr. Lius papers on the effects of barley, he measured that
plants produce more chemicals, the drier the environment becomes.

So when the wildflowers and native grasses in California are trying to
grow in spring, and our rainfall slows down in late spring, perhaps the
weeds may be pumping out more chemicals as the environments gets drier? 
Or when you have a drought, do the weeds pump out more chemicals?

You do not need to know the active chemical in order to use it--you simply
need to know its strength.  Like antibiotics attacking a pathogen in a
petri dish, like you can see at http://www.ecoseeds.com/mrsa.html

Everyone should try some native straw, some tree leaves or pine needles,
or dried stalks of different local native plants on your weed populations
this fall.  Like my petri dish picture, you may be able to see a zone of
effect produced by the straw, leaves or stems, and then use that dosage on
a larger scale against the weeds.

We got our first rainfall from some unusual Indian monsoonal moisture and
thunderstorms last night, so my Nassella straw experiment should start its
effects soon and produce some excellent results by Thanksgiving.  I am
using the native grass straw to suppress the dozen or so annual grass
weeds on the site in Palo Alto, plus trying to work on the solid stand of
Italian thistles.

Sincerely,  Craig Dremann (650) 325-7333