Corn Disease

C.O.R.N. Newsletter Articles

  1. Tar Spot on Corn
    Author(s): Pierce Paul

    Understandably, tar spot has been the focus of our attention this year, as it has been detected in more than 20 counties. It is a disease that is relatively easy to identify based on visual signs and symptoms, but as we approach the end of the season, it may become increasing difficult for untrained eyes to tell tar spot apart from late stages of some other disease. Yes, tar spot, as the name suggests, is characterized by the presence of raised, black, tar-like spots called stromata predominantly on leaf blades (A).

    Issue: 2021-31
  2. Corn Stalks
    Author(s): Pierce Paul , Author(s): Peter Thomison

    Causes of Stalk Rot: Several factors may contribute to stalk rot, including extreme weather conditions, inadequate fertilization, problems with nutrient uptake, insects, and diseases. This year, the combined effects of prevalent diseases such as northern corn leaf blight, southern rust, tar spot, and gray leaf spot may negatively affect stalk quality. However, the extent of the problem will depend on when these diseases develop and how badly the upper leaves of the plant are damaged.

    Issue: 2021-31
  3. Growing Corn
    Author(s): Harold Watters, CPAg/CCA , Author(s): Jason Hartschuh, CCA , Author(s): Amanda Douridas , Author(s): Mary Griffith , Author(s): Elizabeth Hawkins

    Ohio State University Extension and the Ohio AgriBusiness Association will again partner to hold the Farm Science Review Agronomy College on Sept. 14. The event is designed to educate agronomists, Certified Crop Advisers, custom applicators and farmers on current agronomy issues.

    Highlighted speakers include:

    Issue: 2021-30
  4. Author(s): Pierce Paul , Author(s): Mark Badertscher , Author(s): Marian Luis

    Contrary to what was observed over the last three growing seasons when tar spot was restricted to a few counties in the NW corner of the state, in 2021, the disease has so far been reposted in 21 counties, including as far South as Clark County and as far east as Holmes County. In the past, the disease was seen late in the season (after R4), but this year it was reported in some fields at or before silking (R1).

    Issue: 2021-30
  5. close up image of corn at silking stage
    Author(s): Pierce Paul

    This July has been one of the wettest on record, and with the extra moisture, comes concerns about diseases. Gray Leaf Spot (GLS) and, to a lesser extent, northern corn leaf blight (NCLB), have already been reported in some fields, well before tasseling in some cases. Such early disease development could impact grain yield, especially if it continues to be wet and the hybrid is susceptible. GLS is favored by warm temperatures (70 and 90 F) and high relative humidity. NCLB is also favored by wet, but slightly cooler (64 and 80 F) conditions, than GLS.

    Issue: 2021-23


  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. The purpose of the poster is to help corn growers and agricultural professionals diagnose various ear disorders.

  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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