|
Wheat yield prospects across the
southern half of Illinois and southwestern Indiana are potentially
better than last year’s disappointing crop. The 2003 crop was seeded in
very favorable conditions last fall and broke dormancy in very good
condition this spring. Tiller populations are about 4% larger than last
year. That’s a nice positive. However, grain development is at risk.
Frequent rains and heavy dews during the first half of May favored rapid
development of wheat diseases. Septoria leaf and glume blotch has shown up
this week on a considerable portion of the acres scouted. Bleached florets
and the telltale pinkish residue of Head Scab (fusarium)
were just becoming apparent as we counted tillers on this year’s Tour.
This outbreak may not have run its course yet so we can’t say what degree
of yield loss and quality degradation may finally result. While the
proportion of heads that were obviously infected with Head Scab on May 22nd
ranged from less than 1% to about 20%, it’s somewhat likely that more
heads are going to be showing these effects over the next several days.
Just how many additional infected heads there will turn out to be is the
key question.
If it weren’t for the lingering Head Scab
assessment we could say that head size this year was generally much
improved. During April and May of 2002 this area received widespread
excessive rains, leaching fertilizers out of the root zone and causing
extensive water damage to developing wheat. We recognized that we had to
reduce the ratio of tillers-to-bushels in last year’s assessment to about
80% or so. Taking the 60 tillers per square foot observation from the 2002
Tour and applying that reduced ratio gave us a yield equivalent of only
about 48 bushels per acre for the sampled counties. If it turns out that
the fusarium outbreak this year is somewhat limited – much cooler
temperatures arrived before heading was fully complete – we could say that
a ratio closer to 1:1 will apply to this year’s average tiller count.
We’re crossing our fingers and hoping for that outturn, but follow up
visits to scouted fields will tell us which way to go.
It was very apparent that wheat acreage is
increased in Illinois and southwestern Indiana this year. Improved
varieties, better wheat management know-how, and improving prices
encouraged producers to put winter wheat back into their crop rotations
last fall and to expand acreage where the wheat enterprise had never been
taken out of the rotation. It’s a little soon to be certain, but it
appears some of the newer varieties now being grown in the area have
greater tolerance for the conditions that bring on Head Scab. Resistance
to other diseases also has been successfully bred into the more recent
soft red wheat lines and even better varieties are ready to be introduced.
The tendency is for
people to want to compare this Tour’s results with official statistics for
the entire state, but that would be a fallacy. The data collected in this
Tour are not exclusively from Illinois. We always include southwestern
Indiana counties because of the similarity in climate and soil types. Even
if we separated out the Illinois county data, the Tour information would
not represent all Illinois wheat, but only about 75% to 80% of it. The
value of this data set is mainly relational. Year-to-year
differences should be the emphasized when citing the Tour results rather
than comparison to official crop estimates. The percentage changes in
tiller population are more useful than the absolute number of tillers. The
apparent ratio of tiller densities to yield should also be highlighted
rather than the yield per acre. In these ways the Annual Illinois Wheat
Tour results are supplementary to the fuller, more carefully estimated
official yield and production figures.
|