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Re: Goldenrod


The approach I've started taking on some small restorations in Nebraska is
to go ahead and let the plants sort themselves out.  We have a goldenrod
that is very prevalent in one field and I'm not concerned about trying to
control it, partly because I am not convinced that any type of burning or
mowing treatment will be effective.  When these restorations were very
young I did a lot of mowing because I was worried about ragweed, fleabane,
primrose and any other plant that looked like it would dominate the stand,
preventing the establishment of the plant community that I thought
"should" be there.  I tried mowing with the shredder held high to prevent
seed production, opening up the canopy, mowing low, etc. Looking back on
all the work, I really doubt that what I did had much of an effect.
Especially with young stands, species compositions can change dramatically
through time, and I am more content now to just stand back and watch
things proceed.  

Another way of looking at this question could be the following:
down here in the Flint Hills there is LOTS of tallgrass prairie, and as
you drive through it and look around, you can notice that there are some
large areas within any given pasture where a particular species is very
prevalent.  In the fall you can see patches of goldenrod that I would
guess are at least half an acre in size.  It's possible that these are
multiple stems of a single plant or several clones of the same plant.  My
point is, half acre patches of goldenrod in pastures of tallgrass prairie
that are hundreds of acres in size does not strike me as unusual because
I would assume that this is a completely normal way that plant communities 
in a prairie expresses themselves. But a half acre patch of goldenrod in a
three acre restoration or remnant can cause alarm.  However, it
seems to me that the plant community in the small restoration or remnant 
is expressing itself in the same manner as the plant communty in the huge 
Flint Hills pasture, only the context is different.

If you have a specific objective that you want to acheive for your
restorations and decide it is neccesary to control the goldenrod, I can
share with you what I've learned from Clenton Owensby of the Range
Science Department here at Kansas State.  Of primary importance in
controlling perennial plants is the application of the control treatment
(herbivory, mowing, fire, herbicide) at the low point of the plants
carbohydrate (CHO) reserve cycle. When a perennial resumes growth in the
spring, it uses stored CHO to fuel that growth until enough leaf area is
present for photosynthesis to provide the CHO for maintenance, growth,
reproduction and finally storage.  Using this stored CHO draws down the
stored reserves.  Replenishment of stored reserves occurs later in the
season via excess photosynthetic CHO after all maintenence, growth and
reproductive needs have been fulfilled. If you eliminate the
leaf area (eliminate the photosynthetic source of CHO), the plant will 
need to again utilize stored CHO to regenerate leaf area.  If this
occurs at the low point of the CHO reserve cycle, there's a good
chance that the plant does not have enough CHO in storage to resume growth
or vigorous growth.  Do this at the same time for successive years and you
will probably acheive good control of the target plant, plus any other
plant that has a similar CHO reserve cycle.  Conduct the control at any
other time of the CHO reserve cycle and you probably won't affect the
target species at all.  You may even help it because you will unknowingly
be controlling a non-target species that has a CHO reserve cycle that
coincides with your control period, thus reducing the competitive ability
of that plant which could in turn improve the competitive ability of your
target plant.  If any of you have trouble with sumac, we do in Nebraska
and Kansas, this answers the question of why all the spring burning (a
classic method for controlling woody vegetation) doesn't affect sumac.
The low point of sumac's CHO reserve cycle in Kansas Flint Hills is early
June, long after the spring burns.  The question you're probably asking
now is "when is the low point point of goldenrods CHO reserve cycle in my
part of the country?".  I don't know, and I don't know if anybody would
know.  That's why I would advocate just sitting back, watching, and
letting the plants sort themselves out.  You won't be wasting time and
money on futile control efforts, you will still learn a lot about plant
ecology and successional patterns, and you may learn to appreciate
prairies that demand on deviating from our notions of what is
appropriate, normal or representative.

I would advise against mowing tops (to prevent seed production) as
a method of controlling perennials because I think it is a waste of time
and money.  My education and experience (both in mowing tops and in trying
to seed into established stands) lead me to believe that seed production
and seedling germination contribute very little to alterations of species
composition or the spread of any particular perennial.  I am convinced
that perennial reproduction and spreading in a prairie is primarily
asexual - stolons, rhizomes, tillering - there is simply little
opportunity for seedlings to succeed in such a competitive environment.
For a contrasting and interesting opinion on the ability of perennial
prairie plants to germinate and spread in established stands, you can
check out Steve Packard's contributions in Restoration and Management
Notes and the Tallgrass Prairie and Savanah Restoration Handbook where he
discusses his experiences with what he calls "successional restoration".
If you need specific citations let me know.

Steve 
   



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