From: samodena@csemail.cropsci.ncsu.edu (S. A. Modena)
Newsgroups: bionet.plants
Subject: Re: INFORMATION-BASED FARMING
Keywords: telecommunications competitive bar code scanners farming
Date: 12 Sep 92 08:53:43 GMT
Organization: Crop Science Dept., NCSU, Raleigh, NC 27695-7620

In article <adwright.716237830@vincent1.iastate.edu> adwright@iastate.edu () writes:
>>First, resistance to the herbicide will develop in weed species at a rate 
>>proportional to the acreage sprayed with the herbicide.  Second, there may be
>>an incentive to use higher herbicide doses when planting a known resitant crop
>>variety - also less worries about carryover in the soil.
>
>I wonder about that. If we can spray with impunity our resistant corn, we could
>wait till the corn (and weeds) are up and then spray . I am not a weed
> scientist but i would think under such conditions we could use less herbicide
>as well as one that "breaks down" more quickly. I think being able to forget
>about preemergence spraying would bee a real benefit. 

Allen, you lie!  :^)  You sure do understand the advantages of *prescriptive*
use of *post*emergence herbicides VERSUS preemptive, shotgunning with
pre-incorporation or pre-emergence applications of often the very same
chemicals.  

For the greater audience: pre-incorporated chemicals can be "tilled in" during
land preparation before planting.  Preemergence go in during planting.
In both cases, the producer is "guessing" what weeds will emerge.  In
some cases this is a very good educated guess, and in other cases the
person can not reasonably predict.  Then of course, there really are
people who do the "same thing, everywhere, every year just to be sure."

But, postemergence prescriptive (put on only what is needed, only if it
is *actually* needed) requires field scouting and also carries a risk.

When I'm planting, I am definitely in the field and I definitely can
apply a chemical control measure.  But!  If I wait to go with postemergence
and it rains steadily, but not heavily, I might not be able to get
a spray rig into the field.  The weeds are growing and I can't spray
them.  There goes my yield!  On the other hand, if I can get
into the field, I need not put on one dollars more chemical than 
required to control what *actually* came up as weeds!

Oh yes: weeds less than 2 inches high mostly die real easy with reduced 
levels of postemergence chemical application.  Weeds up to 4 inches
are getting stubborn but will mostly die at label recommended rates.

After 4 inches tall, post emergence efficacy is really plummeting.
Now, for those who have actually seen weeds in a real soybeans field,
tell the rest of us: how long is the window of opportunity between weed
germination and when Mr. Weed graduates to the "> 4 inches tall" category?

How would you all manage things?  Are you risk averse?  How much strain and
pressure do you think you can stand making these decisions?

Let me capitalize it for you.  For 100 acres of SOYBEANS, waiting
to use postemergence herbicides could mean spending $0.00 because there
are NOT enough weeds to bother with...all the way up to (easily)
$10,000 to pay for the required chemicals.  Quick: how much do
*your* soybeans yield come harvest time *4* months from now.  And
QUICK: how much will they sell for per bushel anywhere from 4 months
to TWO YEARS from now when you decide to sell off your elevator ticket?

Only molbio types are allow to submit public responces since most of
your field walkers already know the magnitude of the HUMAN dimensions
of this kind of stress.

Of course, for certain philosophical reasons, I suddenly decide (with
no afore-thought) to switch to "organic" control: I will not spray
not matter what weeds come up.  Now how much can I possibly stand to
loose?  Experiment indicates that in soybeans a really incredible
number of weeds causes my yield loss to level off at only 80%!  Actually
this isn't too bad and is none to hard to achieve (so to speak).
Maize, yeah, 70-80% maximum......peanuts? 100%  cotton? 100% 
Well, corn acerage is declining in NC and soybeans is leveled and declining.
Peanuts is popular and important and *everyone* is going into cotton.

Though some of this may not sound like plant biology to many folks, it
nonetheless is!  And to phrase an aspect of this another way, we really
know not-near-enough about weed biology!  Weed biology versus weed
physiological response to herbicide-X.  My boss went to a BIG meeting
in Washington a few months ago.  EPA-sponsored.  Lots of peoples
from all over who have an interest in this environmental consequences
business (isn't that what the EPA is all about?).  So Kathleen
Merrigan, a really sharp vocal staffer for Senator Lehey (Senate Ag
Committe Chair), pointed out (among other things) that farmers suffer
perhaps 60% or more of their losses to WEEDS!  My boss followed her
because he is President-elect of the Weed Science Society and he
asked the audience: how many people here are weed scientists?

Out of something like 150-200 people, he raised his own hand and so
did one other who admitted to being a semi-weed scientist.

So there you are: let's throw another billion dollars at the molecular
biology labs and command them to build us a soybean plant that will
cost less to grow and will use less or no chemicals (high cost inputs) 
and be impervious to weeds and insects and lack of rain and low
soil fertility.

Question for the class: does the USDA competitive grants system have a
section specifically to study weed BIOLOGY?

There are no sour grapes here.  If things are a little tilted, it is more
or less the traditional aggies fault as far as I'm concerned.  If we
think we are so smart, how come we aren't better funded and more successful
at solving some of these major problems?

Have a nice one!  :^)

Steve
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|     In person:  Steve Modena     AB4EL                           |
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