Stalk quality concerns arise
Question: What factors affect stalk quality?
Brad Ott: As we move into fall, there is increased interest about issues that will affect crop development and harvest due to abnormally late planting dates for most of the state. Excessive early moisture and precipitation typically lead to nitrogen loss, increased disease management, decreased late-season stalk stability and higher probabilities of harvest loss.
Question: How does nitrogen loss work?
Ott: N loss can be associated with volatilization, denitrification and leaching. The latter two are more common for significant loss in Ohio and are a result of excess moisture in the spring. The earliest-planted corn will be subject to greater N losses especially if preplant N was applied. N loss can affect late-season corn plant health by reducing standability and potentially vectoring stalk disease.
Question: How is N loss detected?
Ott: As N supplies become limited during the grain-fill period, the plant will tend to cannibalize the stalk to provide nutrients to the developing ear. Although stalk cannibalization can occur in any hybrid, overall stalk strength will vary among hybrids. Visit with your seed supplier to determine which hybrids are more likely to suffer from late-season stability issues. An easy test is to walk though the field and pinch the stalk 12 to 14 inches above the ground and below the ear. Target areas of the field that are poorly drained and hillsides where leaching and runoff are a concern.
Question: What causes stalk disease?
Ott: Another factor affecting harvest stability is the presence of stalk rots and diseases. Three factors need to be present to cause infection: a pathogen, a host and a suitable environment. Most common stalk diseases require moderate temperatures and available moisture to cause infection. Temperatures tend to be cooler (less than 86 degrees F) in the fall, and humidity can remain high. These two factors supply the environmental conditions needed to sustain disease development.
Question: What stalk diseases should I look for?
Ott: Two common stalk diseases are diplodia and anthracnose. Diplodia stalk rot can be seen as small, black dots on the outside of the stalk beginning at the base of the plant and moving vertically through the stalk. Anthracnose symptoms can include leaf blight, top-kill of the stalk and stalk lesions. The stalk rot phase can be seen as black or darkened lesions at the base of the plant above the brace roots. Later, the pith will appear shredded and discolored. Late-season disease tolerance is hybrid-specific, and susceptible hybrids should be scouted early for disease pressure.
Question: Why watch for root lodging?
Ott: Due to our excessive early-season moisture, root lodging may be a concern as harvest nears. Root mass reaches its maximum size near R1, or silking. We already have seen plants lodged due to wind and the lack of a deep, penetrating root system. With excess early moisture, the plant is not required to root deeply, and nodal and seminal roots may remain shallow.
Question: What role does compaction play?
Ott: Compaction also affects the ability of root systems to establish early. Plants may appear to be standing upright, but a late-season rain can soften the soil, and high winds can lead to lodged corn. Another simple root lodging test is to walk through a field and randomly kick a stalk near its base. If the plant falls or is easily pulled from the ground, root lodging may be a concern. While scouting your fields, target areas where compaction is likely for increased probabilities of root lodging.
Question: Where can I get help?
Ott: Discuss these issues with your seed supplier and/or agronomist to develop scouting and harvesting plans to maximize quality and efficiency. In 2011, Ohio planted nearly 70% of its corn in 10 days. Be ready to harvest quickly if standability is a concern.
This article published in the September, 2011 edition of OHIO FARMER.