[APWG] Substitute local native ecotypes, for the exotics in the seed mixes?

[Craig Dremann - Redwood City Seed Company]

Dear Alison and All (especially other DOT readers),

Thanks for your email.

TINY TEST PLOTS:  If Nebraska DOT is already using native grasses along
the roadsides, but mixed with exotic perennial weedy grasses, then the
Tiny Test plots would only need be to find substitutes for the exotics, by
testing fast-growing natives?

MIXING EXOTICS with Natives, is very, very  bad for your native planting,
because of the allelopathic effects of the exotics, plus any perennial
exotics do  not fade out of the picture.  The only exotic annual that I
have seen fade out within one season, is cultivated oats, and that is it. 
Every other species of exotic especially those used as pasture grasses or
roadside stabilization, whether annual or perennial, gets naturalized to
some degree, within the native ecosystem.

WHAT DOES YOUR STATE FLORA SAY? A good guide to the potential problems
with mixing exotics with your natives, is to look at a copy of your State
flora, if one has been written.  If the species you want to mix in, has
ever become “naturalized” or “escaped from cultivation” in that it has the
ability to grow and reproduce on its own, then NEVER ever add that exotic
species to your native seed mix.

QUALITY OF SEED STOCKS?  So if you are using natives regularly for
roadsides, then the next two issues, is the purity of seed stock, in terms
of weed seed and “other crop” seeds.

This is where we run into big problems here in California, native seeds
are produced by seed growers, but are legally allowed to have a certain
percentage of weed and other crop seeds mixed in.

Those few percent of weed or other crop seed can ruin your whole planting,
so always insist on a “Zero, Zero, Zero” standard for the seed growers to
produce, which is Zero noxious weeds, and Zero weed seed, and zero other
crop seeds.

LOCAL ECOTYPES? I hope that Nebraska is using the same ECOTYPE program
statewide, as Iowa DOT?  In that all of the native seeds sown along the
roadsides in Iowa are local genetic material?  If not, then let the
conversion begin in Nebraska and all the other states!

You can read about the importance of native ecotypes, with a massive
bibliography at the end, at
http://www.ecoseeds.com/juicy.gossip.three.html

UC Davis did common garden experiments with some of our California native
grasses in 1994 and found that only the local populations persisted over
time.  So you could get an excellent stand of native grasses in a planting
for the first few years, and then if it is not local genetic material,
watch it disappear over time, as short as 3-4 years.

Sincerely,  Craig Dremann (650) 325-7333