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

[Craig Dremann - Redwood City Seed Company]

Dear Ty and All,

Knowing which native plant give off the strongest herbicides and which are
the strongest weeds, can make you weeding life so much easier, and you can
have the native plants help you as allies in your efforts.

For example, yesterday I drove 400 miles round trip, just to pick up a
single bale of Stipa native grass straw, Nassella pulchra, whose straw
contains one of the strongest herbicides of our native grasses.  It was
like buying a 5 gallon bucket of Roundup in a bale.

I am working on some test plots in the hills of Palo Alto, a beautiful 70
acre canvas that is currently solid exotic grasses, and I want to see what
can be done, to get it back to 99.5% native plant cover.

So in test plots last year, I looked at the interaction between adding
fertilizers to modify the weed cover, and also adding California poppies,
that you can see photos at http://www.ecoseeds.com/arastradero.html

The ideal situation is if you are left with any weeds, you want to get all
perennial rye plants, rather than any wild oats, ripgut, blando, foxtails
or zorro grass, because the perennial rye has the weakest herbicide
effects of the six grasses.

So what I am going to do, is wait until the first rains bring up the weed
seeds, scatter a thin layer of Stipa straw on top of them, add poppy seeds
plus fertilizers, and wait 3-4 months and see what I get, like baking a
cake but it takes a little longer.

What I am hoping for is no foxtails, zorro, ripgut, blando, or wild oats,
maybe <5% cover of perennial rye and 95% cover of the poppies.  Then next
autumn, start sowing in the local native grass seeds, like the Stipa
itself.

So I am going to give the weeds a double dose of allelopathy, first with
the Stipa straw, then with the poppy plants producing it in their roots--
especially effective against annual grasses.

You can think about this allelopathy issue, as the land is one big giant
petri dish.  And all the plants, all of the natives and all the weeds, are
each giving off herbicide-like chemicals like antibiotics at a greater or
less amount.  We need to go out and see what the relationships are, and
use them to our advantage.

Many of our Endanagered plant and animal species in the West are grassland
species, and knowing which weeds are the most toxic against the native
plants, and knowing which native plants are the strongest against the
weeds, can help save a lot of time and effort when managing or recovering
those species.

Sincerely,  Craig Dremann (650) 325-7333