Importance of Scouting Corn in 2011

By Bill Mullen, Director of Agronomic Services, Seed Consultants Inc.

I never imagined corn planting throughout Ohio and Indiana would start around the end of May and finish up by mid June. Saturated soils kept many from ideal planting situations. In past years, farmers were able to work with four to five inches of good dry soil to plant into. In 2011 we were fortunate to have two to three inches, at best. Below this planting depth, there was nothing but mud. With the warmer temperatures, corn seed pushed through the ground fast and the growth process started. Fields look good from the road, as they always do, however there are issues out there that still need to be addressed. Walking corn fields will show the true condition and identify possible issues that could delay crop harvest.

The first issue affecting our corn crop today is the early development of the root system especially in those areas of the field where the plant roots were impacted by shallow compaction. Compacted soils have always been a challenge attaining high yields. Good nodal root development allows for plant uptake of moisture and nutrients. Because of not having good, loose soil for the nodal roots to develop normally, many corn plants lodged when rain and heavy winds rolled through around mid July. With the saturated soils and shallow root system, many plant’s roots came partly out of the soil. Research has shown these plants will recover without much yield loss. Had these conditions occurred shortly after tassel, more yield loss could be expected.

Corn fields throughout Ohio and Indiana have struggled due to lack of moisture. Rain makes grain, it always has and always will. When plants go through a moisture stress, more is expected from the corn roots to supplement the plant’s needs for moisture and nutrients, especially nitrogen and potassium. Both are needed for good stalk integrity. Potassium is important for root formation and pith cell development within the stalks. There were fields, this year, that showed early potassium deficiency. In many instances this deficiency is not due to the lack of potassium in the field but occurs when the roots are restricted due to compacted areas in the field.

Leaf health is essential for sugar production, taking care of grain fill, and protecting against root and stalk rots. Diseases such as gray leaf spot, northern corn leaf blight, and Anthracnose leaf blight will reduce leaf tissue. Loss of leaf tissue means less photosynthesis, reducing sugar production within the corn plant. As you walk your corn fields, pay attention to the leaves below the ear leaf for disease lesions. From these lesions, you are able to identify what disease is present on the plant. Having the pocket Field Guides from OSU or Purdue with you helps for proper disease identification. For some hybrids with poor to low disease tolerance, a fungicide application is very beneficial.

Higher yields are expressed as more potential kernel sites, demanding more sugar out of the stalk and roots. Sugar is one of the factors associated with resistance to both root and stalk rots. During the grain fill period, under moisture stress, the corn plant will cannibalize itself, pulling moisture and nutrients out of the stalk to fill the need but as a result of this stalk integrity will weaken and possibly allow stalk rots, under the right conditions, to occur later on.

When walking your corn fields, always pay attention for any insect issues that could be affecting the stalk and roots of the corn plant. European corn borer, 2nd generation could be present on those hybrids that do not have the Bt trait. Taller plants from our later plantings in June without this trait are the most susceptible to damage. It will weaken the upper portion of the stalk as well as the shank of the ear causing yield loss, dropped ears, and possibly lodging later on.

Plants not having the corn rootworm trait could have damage from corn rootworm larvae feeding on the nodal roots. With a shovel, carefully dig around the corn plant, not cutting off the roots. Examine the roots for possible injury. Extensive feeding can lead to severe yield losses and stalk quality issues later on. In mid-July numbers of Western Bean Cutworm adults continued to increase. This insect, under heavy infestation, can inflict yield loss and poor grain quality by cannibalizing the ear.

There are many, good corn fields throughout Ohio and Indiana today. There are issues out there that can have an effect on the yield potential of the corn crop but cannot be identified from the road. Until you leave your vehicle and walk your fields in different areas, you don’t know how good the stand is or what issues may affect this year’s harvest. Taking the time to walk your corn fields will give you a good idea on the condition of the corn crop in your fields today.

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