Yield reports are beginning to trickle in with some interesting results.

In some areas soybeans are in the 60-80bu/acre range and corn is running from 120-278bu/acre. Although the drought took away some top yields growers are finding yields are not as poor as they would have expected given the situation. I would like to focus on the corn situation. The concern now for standing corn is harvest loss due to ear drop and stalk rot. There are a host of reasons why corn lodges and depending on the reason may impact not only the quality but the health of the crop and impact a ration as mycotoxins may result. Many dairy farms experience the call from the nutritionist that mycotoxin levels are high either in high moisture corn or from silage. Few producers track back the infected crop to where it originated in the field. In many cases it can be traced to a severely infected stalk or ear rot section of a field.

In a recent NCGA combine harvest of 237 bu/acre dry corn yield was limited due to stalk rot and premature death. The producer made the decision to harvest early when the moisture was 28% due to the stalk quality. One may consider this a bumper crop but yields under the same management a mile down the road were in the 270’s that did not show signs of stalk quality problems. The field in question also was beginning to drop its ears. Conducting a population test some ears fell easily when bumped and in the absence of pests such as corn borer this indicates a stalk issue. This field was subjected to several weeks without rain and the plant stress caused the plant to move nutrients from the stalk into the ear to preserve its reproduction and thereby weakening the plant to the point that pathogens infect and pre mature plant death results, including dropped ears. Keep in mind too that these hybrids are standing now with between 32 and 35,000 plants per acre which also adds to the stress level on the crop. These types of fields need to be identified now and early harvest despite drying costs must be considered. Further in some areas where hail occurred ear molds are also prevalent and again early harvest is the best route to prevent feed out issues.

This is not enough, however, the area in the field needs to be identified and a plan must be put into place and followed up on. The first step in successful management of stalk rot is to recognize that it can and is manageable. Second, growers need to plan in winter to combat stalk rot. Finally, growers need to follow the plan of attack.

Stalks may lodge due to insect, genetics of the hybrid, and more likely disease brought on by many factors of importance including soil potassium levels. A trained eye will determine which is responsible. In all cases where stalks lodge and problems occur a soil test from the area in question and coupled with an area that shows no sign may prove fruitful in diagnosis. If growers have a problem, in diagnosing these fields, coordinate a visit with an Extension Educator or one of the many Certified Crop Advisors. This is usually done after the fact and is useless for this year’s crop but will allow you to change things for next year. Let’s plan the attack now.

The first attack will be hybrid selection. An old Extension proverb is to never plant the same hybrid in the same field next year. Sounds simple? Follow it. I have been in many fields where this simple message is ignored and disaster occurred in the field.

Second choose hybrids that not only maintain yield but have high resistance to stalk rot. I am looking at seed catalog now and can pick three for my farm that have very high resistance to stalk rot pathogens. At winter meetings ask the dealers for their top picks then ensure to select with stalk rot resistance (anthracnose is the major one rated) in mind. One final note is some cooperative research I am involved in suggests Bt corn can reduce the incidence of disease invasion through keeping European corn borer from eating into the stalk. Be sure that is in the balance of your hybrid decision.
With soil test in hand get to the plant food dealer and correct any deficiencies in nutrients putting the highest priority on potassium. Expensive? Yes but you cannot afford the consequences of potassium deficiency. I have several personal experiences where very low potassium levels caused stalk rot in the field and this was compared to areas of the field with no stalk rot with adequate potassium. It is also well documented in the literature.

Plan to avoid the “sins” of soil management. If the soil is wet stay off it especially with the planter! It is easy for me to say that and I am aware of the farmer’s plight. But when soils are wet sidewall compaction at planting time can cause deficiencies in nutrients and eventually stress the plant and allow it to become susceptible to stalk rot pathogens as well as many other problems. If you do decide to “sin” be sure your planter is retrofitted with finger type closing wheels to break up the smearing action of the double disc openers. It makes no sense to correct a potassium deficiency and then not allow the roots to absorb it due to compaction. I could talk more about compaction at a later date for we are finding some interesting results on dairy farms.

Plant early to allow the plants time to generate roots that will reach water deep in the soil profile, avoid drought stress and subsequent invasion by stalk rot pathogens. This year is a great example of that. Strive to have ninety percent of corn planted on the early side of the ideal planting date.

Now that you have properly selected a hybrid, planted the hybrid early, corrected potassium deficiencies (within fields) and alleviated compaction it’s time to begin harvesting disease free corn silage and grain that will avoid that call from the nutritionist.

Other References: Scouting for Stalk Rots