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Cotton Diseases: A Lineup of 2021 Suspects

February 3, 2021
This agronomic image shows a cotton field.

Cotton field

Are you prepared to tackle tough cotton diseases this season? Target spot and areolate mildew can have serious impacts on cotton yield if left unchecked. As you plan your disease management strategy, use this information as a refresher about some of the mid- to late-season problems to keep an eye on:

Target Spot

  • Damage: Target spot may cause significant defoliation very quickly after infection and has become increasingly more common in the U.S. In severe cases, it can cause yield losses of more than 200 lbs. of lint per acre. Factors that could lead to disease development include rank growth, cotton grown in short rotation, too much irrigation, higher rainfall and warmer temperatures.
  • Symptoms: This disease is usually distinguishable by dime-sized spots with circles inside that make the spot look like a target. Target spot causes plants to lose leaves from the bottom first before progressing upward. It is sometimes confused with Alternaria or Stemphylium leaf spot, but you will usually see target spot lower in the canopy.

Areolate Mildew

  • Damage: Before 2017, this fungal disease was typically only found in southeastern GA but has since spread. In 2018 and 2019, NC cotton fields also experienced damage from areolate mildew.
  • Symptoms: This late-season disease favors wet and humid weather and causes a characteristic powdery, white-to-gray growth on the underside of leaves. It can cause defoliation and impact yield if it occurs more than 4 weeks.

Boll Rot & Hardlock

  • Damage: Severe problems from boll rot and hardlock are an annual concern if you experience cool, wet weather late in the season, such as extended rains from a hurricane or tropical storm. Hardlock caused by Fusarium verticillioides can be devastating in the FL Panhandle.
  • Symptoms: Boll rots begin deep in the cotton canopy. To a certain extent, rotted bolls as well as bolls with hardlock – where the boll will remain unopened even at maturity – can be observed in low, scattered quantities in almost every cotton field.

Use a Tougher Defense

Properly timed fungicide applications can be very effective to manage these diseases. For cotton growers facing possible yield loss due to disease, we recommend Miravis® Top fungicide. Custom-built with one of the highest-performing SDHI molecules available, Miravis Top delivers tougher disease control in cotton to protect yield and ROI potential.

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