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The 2002 growing season was generally favorable for the development of
soft winter wheat in the region and the Tour found good yield prospects.
Tiller density recovered from the thin stands found last year, but head
size is not so large. Cool temperatures during a prolonged period of
excess rainfall may have suppressed chronic diseases. We found the usual
yield robbers – Head Scab, Septoria leaf and glume blotch, rust,
powdery mildew, cereal leaf beetles, and army worms – but not in
economically significant levels. Something else has caused smaller head
size. We think leached fertilizer and shallow root systems are limiting
grain development. Consequently, we would not use more than the 1:1
ratio for most of the wheat observed on this year’s Ohio/NE Ind/SE
Mich Soft Wheat Tour |
The
crop this season appears to also be developing more slowly than usual
and harvest should be a few days later in starting. Growing Degree Day
accumulation has been behind the normal pace. Participants also felt
they were seeing fewer fields as they traveled along assigned routes.
The
Tour does not evaluate the entire wheat crop within any of the soft
wheat states. To make the most of limited time and voluntary resources
only counties with the highest concentrations of wheat acres are
sampled. In Ohio we look into about 28 counties, 8 counties in NE
Indiana, and 4 counties in SE Michigan. By returning to these same areas
the tiller counting and crop observations find relative changes
annually. We intend the evaluation to supplement official crop
projections. |
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The
28 Ohio counties that are targeted in this evaluation contain about 70%
of the wheat acres in the Buckeye State. They account for about 73% of
total wheat production, give or take a percentage point. The composite
yield average for this subset of Ohio counties typically yields from 1
to 3 bu/acre above the statewide yield average.
Tillers
per one square foot: For quick and easy yield calculating we count
tillers. There is approximately one bushel per acre of yield potential
for each tiller in one square foot --- a 1:1 ratio.
However, in very good growing conditions where head size may be
visibly larger than normal this ratio may be tweaked upward. In the
event of heavy disease pressure or other severe stress the ratio should
be discounted 10% to 40%.
The
table below illustrates this rule of thumb. You can see that the bad
Head Scab outbreak in 1996 pulled yields down sharply. Despite a good
tiller count, head size and grain weight were so poor the ratio between
tillers per square foot and bushels per acre was knocked down by about
40%. At the other extreme, the very large head size and heavy grain
weight in 2001 boosted the ratio by an additional 20%. |