Corn Disease

C.O.R.N. Newsletter Articles

  1. grey leaf spot
    Author(s): Pierce Paul

    Foliar diseases, especially Gray Leaf Spot (GLS), are beginning to show up in some corn fields. This is not at all surprising, given that the crop was planted relatively late and it has been wet and humid in some areas. GLS is favored by humid conditions, particularly if temperatures are between 70 and 90 F. Foliar diseases of corn are generally a concern when they develop early and progress up the plant before grain fill is complete. This is especially true when the hybrid is susceptible. In most years, GLS and NCLB usually develop late or remain restricted to the lower leaves.

    Issue: 2018-20
  2. Early Corn Coloration – Green, Purple, or Yellow?
    Author(s): Alexander Lindsey , Author(s): Steve Culman , Author(s): Peter Thomison

    Corn seedlings often turn yellow (due to low nitrogen uptake and/or limited chlorophyll synthesis) or purple (reduced root development and/or increased anthocyanin production) under cool, wet conditions. Some hybrids are more likely to increase anthocyanin (purple pigment) content when plants are cool. Yellowing or purpling of corn plants at this stage of development generally has little or no effect on later crop performance or yield potential.

    Issue: 2018-16
  3. Author(s): Pierce Paul

    With corn now beyond the R4 growth state in most fields, there is really nothing you can do about southern rust in terms of fungicide application. However, correct diagnosis of this disease is still very important from the standpoint of identifying the hybrids that were most severely affected. Although our growing conditions generally do not favor this disease and we may go for another several years without seeing as much southern rust as we did in 2017, we still need to identify those highly susceptible hybrids.

    Issue: 2017-30
  4. Author(s): Pierce Paul

    Both southern and common rust have been confirmed in multiple corn fields across the state, but as is usually the case in Ohio, the latter is much more wide-spread than the former, and most of the affected fields are in the southern half of the state. Southern rust is characterized by the presence of small, circular, light orangish pustules predominantly on the upper surface of the leaves, whereas common rust produces larger, more elongated, and darker (cinnamon-brown) pustules on both leaf surfaces.

    Issue: 2017-24
  5. Author(s): Pierce Paul

    Ohio corn producers are reporting more rust on corn this year, and are concerned that it might be southern rust, the rarer but more damaging of the two major rust diseases that affect corn in state. Based on the fact that they both produce rusty looking pustules on the leaves, producers may actually be confusing common rust with southern rust, especially when they are not occurring side-by-side on the same leaf. The table below provides some key differences between the two based on the characteristics of visual symptoms and conditions favorable for development:    

    Issue: 2017-22

Publications

  1. Abnormal Ear Diagnosis Poster,  ACE-1. Farmers frequently encounter abnormal corn ears in their fields when the crop has experienced a major stress, such as drought, temperature extremes, disease, insect injury, or misapplied chemicals. These abnormalities often affect yield and grain quality adversely. In this poster, ten abnormal corn ears with distinct symptoms and causes are highlighted.

  2. Corn Disease Management in Ohio, Bulletin 804. Five to 15 percent of Ohio's corn crop is lost to disease each year, amounting to nearly $100 million in lost farm income. Corn diseases include seedling diseases, leaf blights, stalk rots, ear and kernel rots, and viruses. This bulletin describes the disease symptoms, provides color images, gives the environmental factors favoring the disease, the method of transmission and infection, and management options for the major diseases affecting corn in Ohio.

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