[APWG] Allelopathy knowledge can save time when weeding+restoring areas

[Craig Dremann - Redwood City Seed Company]

Dear All,

Thanks for your email.  I got a couple of offline questions about knowing
the id of the active herbicide chemicals in the plants, and why use 2
inches of the Stipa straw?  I am posting my reply, as it might be of
interest to all:

Even if we do not know exactly what chemicals in these plants are working
against the weeds, if we figure out how to use them to our advantage,
perhaps they could save a huge amount of time and labor for all of our
weed management or restoration project?

If we think of these chemicals as antibiotics, and we are applying them to
a macroscopic petri dish, then they could be visualized that way.

Instead of waiting for someone to id the chemicals that were active before
I could use them,  I thought it was more important to invent a method to
measure the chemical effects of one plant against another, and give each
plant a number 1-100 to indicate their power?

Then it becomes like a poker game, where a 8 beats a 3 for example.

I am using 2 inches of Stipa mulch, for its long lasting effect at the
site, because of the multi-layered dormant weed grass seeds in the soil.

On the site in Palo Alto, there is a 150 year history of the introduction
of weed grasses buried in layers like an archaeological site, with the
most dominant grass suppressing the germination of the dormant seeds of
the next, and so forth, and there are at least 5 layers out there.

So let's say from the pictures at http://www.ecoseeds.com/arastradero.html
that wild oats is the most dominant layer, so when you suppress the wild
oat seeds from germinating, then the ripgut grass seeds get to germinate. 
Then when you suppress the ripgut, the Blando brome is allowed to
germinate.

When you suppress the Blando, the Perennial ryegrass may by your final
layer of weed grasses.  But wait--you are not done yet with the dormant
weed seeds!

Now all the different annual and biennial forb weeds that were suppressed
by all the grasses will want their turn to sprout, once the suppression of
the allelochemicals of the grasses has been released.

Before I begin any large scale project, I want to know accurately what the
allelochemical strength for each weed species and each native species on
the site.  Then as the team captain for the natives,  I know which natives
I should pick for my team to beat the exotics.

For the cheatgrass, just planting back the local native grasses will
permanently take care of that weed nicely, as you can see my photos from
the 600 acres that were planted in the Great Basin at
http://www.ecoseeds.com/greatbasin.html

I am going to look forward to others reading these two lists, who will
experiment with this idea over the next year, and we should share our
results next summer, and see what strong allelopathic native and exotic
plants we have come up with in the different parts of the country?

Sincerely,  Craig Dremann (650) 325-7333