[APWG] Natural herbicides, use grasses or forbs on trees

[Craig Dremann - Redwood City Seed Company]

Dear Kim and All,

Thanks for your email about the Tree of Heaven.

In general, most plants are somewhat immune to their own allelochemicals,
so if you are going to play the natural herbicide poker game, it is best
to use the Tree of Heaven leaves on something like an exotic grasses, and
find the another species of plant that can beat the tree seedlings, which
may be a wheat straw or alfalfa hay or dried mustard stalks.

When working with natural allelochemicals, consider that the four main
groups of plants, trees, grasses, herbaceous perennials, and shrubs, work
similar to the kid's game of rock-scissors-paper.

Dried grass leaves are usually stronger than tree seedlings, and dried
herbaceous forb leaves are usually stronger than grasses, especially
plants in the legume family.

And there are many,  very strong interactions between the forbs, because
they are always fighting among themselves, out in the ecosystems.

I have been able to keep an area completely free of annual grasses for two
years, using forbs, when they have a long-lasting allelochemical in their
dried stalks, that are leached into the soil by rain.

This long-lasting natural herbicidal activity may be useful in managing
some of the West's worst annual exotic grasses, like the tens of millions
of acres of flammable foxtails, ripgut and wild oats in the West, and the
flammable and sagebrush ecosystem-destroying cheatgrass on BLM lands in
the Great Basin, for example.

We will need to get some serious annual Federal grants going, hopefully
from the agencies and military that need these natural chemicals to manage
the exotics on our military and public lands, so that we can get these
products into commercial circulation.

For example, there at the Fort Hunter-Liggitt Army base,  about 150 miles
south of me, a big field was formerly used for landing for parashute
jumping by the soldiers, but had to be abandoned when it became solid
yellow starhistle.  If you Google star thistle and Hunter Liggitt, you can
read some stories.

The base hired the USDA, ARS to discover a way to manage the thistle, but
so far, probably been using the old-off-the-shelf chemical herbicides and
the old bio-controls, and maybe the ancient burning, mowing  or grazing
techniques, that have never worked quickly or efficiently.

I don't think anyone has ever looking into the new natural herbicides yet.

What I am suggesting about the new natural allelochemicals, when you hit
the right one, is like getting a Royal Flush in poker, with immediate 100%
response on suppressing exotic weed seedlings, for up to two years.

Sincerely,  Craig Dremann (650) 325-7333