It looks to be another warm week across west central and northwest Iowa. The majority of corn and soybean fields look to be developing very well, although some areas still need rain. Pockets in Monona and Carroll counties have missed recent rains and are suffering under this heat. Insects continue to be a problem in many fields, particularly corn rootworm. Mid to late season disease should become more prevalent as both the corn and soybean crops as they attempt to fill grain.

Corn development has surpassed the pollination period in most fields and may be nearing R4 (Dough) in some of the earliest planted fields.

R3 Stage (Milk) commonly occurs 18-22 days after silking. The R3 kernel displays yellow color on the outside, and the inner fluid is now milky white due to accumulating starch.

R4 Stage (Dough) commonly occurs 24-28 days after silking. Continued starch accumulation in the endosperm has now caused the milky inner fluid to thicken to a pasty consistency. The R4 embryo has greatly increased in size from the R3 stage. The shelled cob is a light red to pink color due to beginning color changes of the surrounding materials (lemmas and paleas). The reduced fluid and increased solids within the kernel at this time produce a doughy consistency. Just prior to R5 kernels along the length of the ear begin to dent or dry on top.

Soybean Development continues to progress to pod elongation and possibly seed fill in some fields. Seedfill is the most crucial period of plant development in terms of seed yield determination.

As mentioned in previous newsletter, be on the lookout for Bean Leaf Beetles, Two Spotted Spider mites, and Grasshoppers. The soybean aphid appears to have become an economic problem in some northeast IA soybean fields. This pest has not been found in our part of the state yet, but we need to be on the lookout. The aphids are located on the underside of the newest trifoliate leaves.

For those running short on corn silage, corn can be chopped early and fed to meet demand until the crop is ready for harvest and storage. In general, the digestibility and feeding value is equal from blister to maturity. Protein tends to be higher for more immature silages. On the downside, dry matter intake is typically less with more immature silages, most likely due to the higher moisture content. If the corn has been under drought stress, nitrate accumulation may be a concern. Most nitrate problems accumulate in the lower portion of the stalk. By harvesting a little higher than normal, nitrate problems may be avoided. Of course the most accurate and safe method to determine nitrate concentration is to send a sample to a lab for testing.

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This page last updated on 02/03/04

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