Manhattan, Kansas
July 20, 2007
Test weights of wheat have been
unusually low in much of Kansas this year, especially in areas
east of Dodge City, said Jim Shroyer,
Kansas State University
Research and Extension crop production specialist. That affects
everything from seed quality to grain quality.
The basic reason is that leaves were diseased or killed at a
critical stage of wheat development this year, said Erick
DeWolf, K-State Research and Extension plant pathologist. Itīs
not unusual for leaves of wheat in Kansas to die before the
kernels have filled, but this year the leaves died earlier than
normal in many cases - as early as the flowering stage in the
most extreme cases.
By the calendar, leaf rust did not come into Kansas much earlier
than normal and there wasnīt any early heat or drought stress,
so why did the leaves die at such an early stage of growth?
"The reason is that wheat development was slow this spring, due
to freeze injury and cool weather. When leaf rust came in, the
wheat was in an earlier stage of development than normal,"
DeWolf explained.
"In addition, other leaf diseases such as powdery mildew, tan
spot, and speckled leaf blotch continued to be active later into
the spring than normal because of the cool, wet conditions.
Along with leaf rust, these diseases eventually helped kill the
leaves at an early stage of wheat development in some cases."
"The early April freeze either killed or damaged the main
tillers. If the main tillers were killed, secondary tillers
began growing. Even if the main tillers were only damaged, they
resumed growing slowly.
Where the freeze damaged the stems, the wheat suffered from
limited flow of water and nutrients to the developing grain. The
end result was that the wheat developed more slowly than normal
after the first of April, and was at a critical stage of kernel
development when the leaves were lost," the agronomist
explained.
Waterlogged conditions also contributed to low test weights,
Shroyer said. Where wheat is waterlogged, the roots are starved
of oxygen and cannot supply the grain with water and nutrients.
Wet soil conditions can also lead to crown rot, which reduces
the flow of water and nutrients to the grain.
Other causes of low test weight include the presence of cheat,
rye, and other grassy weeds; an unsuccessful attempt of the
plants to completely fill a 3rd or 4th berry; rainy weather at
harvest time; and inherent variety differences, Shroyer said.
K-State Research and Extension is a short name for the Kansas
State University Agricultural Experiment Station and Cooperative
Extension Service, a program designed to generate and distribute
useful knowledge for the well being of Kansans. Supported by
county, state, federal and private funds, the program has county
Extension offices, experiment fields, area Extension offices and
regional research centers statewide. Its headquarters is on the
K-State campus in Manhattan. |
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