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Watch for kernel, ear rots in corn crops
By Clyde Burchett
Pioneer Hi-Bred agronomist
Kernel rots and ear rots are fairly common in fields with heavy corn earworm and corn borer feeding in the ear. Damage, due to ear and kernel rots, can be minimized by harvesting early and rapidly drying grain to 15 percent moisture to prevent further mold growth in storage. For long-term storage, grain should be dried to 14 percent or less. Below are descriptions of some of the more common ear molds:
--Diplodia: Early-season infection produces bleached husks and shrunken, upright ears. Later infection produces a white mold, usually beginning at the base of the ear. Diplodia is the most common ear rot. There is no known toxin associated with Diplodia.
--Fusarium: Infected kernels are salmon pink to reddish-brown with a powdery or cottony mold growth. When shelled, kernels often appear black. Fusarium and Gibberella are toxic to hogs.
--Gibberella: Infected ears have a pink to red rot starting at the ear tip.
--Aspergillus: A yellow-green mold growing on or between the kernels. This fungus is capable of producing aflatoxin.
--Penicillium: Infected kernels have a bluish-green mold growing on them, usually at the ear tip.
Soybean varieties can mature differently from year to year, hence the term relative maturity. Depending on the year, two varieties may mature at the same time one year, or be several days apart the next. Some years they may switch, the apparently earlier variety maturing later. Besides basic genetic influences on maturity, environment plays a big factor in soybean maturity. In-season stress caused by soybean cyst nematode or diseases such as sudden death syndrome, charcoal root rot or Septoria spot can hasten physiological maturity. This helps explain why some varieties seem to "turn" early one year, but "hang on" the next.
Wheat seeding rate: The best seeding rate for most Wheat varieties is about 1.4 million seeds per acre. Depending upon seed size, this may vary from 95 to 135 pounds per acre. Specific seed size information can be found on each bag.
Research throughout the Midwest has demonstrated that one-third of recommended nitrogen (N) for Wheat should be applied at planting, with the remaining two-thirds applied in the spring. This balance of nitrogen helps ensure adequate growth of the Wheat in the fall and an ample supply of N in the spring when nutritional needs are highest. As a general rule of thumb, Wheat needs 1.25 pounds of nitrogen per bushel of expected yield.
Wheat responds to phosphorus (P) applications. Wheat is thought to be more sensitive to P deficiency than most other crops. Part of the reason for this is phosphorus availability in soil is limited in cold weather and early Wheat development is during colder temperatures than summer crops. Therefore, phosphorus fertility is crucial for good fall and early spring growth in winter wheat. Simply make sure soil test targets for P is met. An adequate phosphorus soil test level would be P at 45 pounds per acre.
Editor's note: Crop Talk is brought to you by agronomists serving your community to keep you informed about current growing conditions and important management issues. Clyde Burchett, Higginsville, Mo., is an agronomist with Pioneer Hi-Bred.
Date: 9/23/04
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