Cercospora Leaf Blight

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Cercospora Leaf Blight

Photo Credit: Trey Price – LSU

Cercospora leaf blight (CLB) is caused by a fungus (Cercospora kikuchii) which may come from infected seed and/or debris from previous crop. Upper leaves exposed to the sun develop light-to-dark purple areas, depending on variety. This discoloration can deepen and extend over the entire upper surface of affected leaves, giving them a leathery, dark, reddish-purple appearance, highlighted with bronzing and/or blighting. Symptoms do not usually appear until reproductive growth stages. Numerous infections cause rapid necrosis (deadening) of leaf tissue, resulting in defoliation. The same fungus causes purple seed stain which varies from pink or pale purple to dark purple. Infected seed may not show symptoms.

  • Variety selection – some varieties may have higher tolerance to CLB and earlier maturing varieties may escape any infection, ratings can be found on UT pdf publications and searchable database
  • Timely fungicide, prior to disease development, may limit disease and protect yield, although fungicide resistance to QoI/Strobilurin and MBC fungicide groups has developed. Links to Fungicide Efficacy Table – mobile version or pdf

clb blight symptoms - photo credit trey price lsu
Cercospora Leaf Blight Symptoms
Photo Credit: Trey Price – LSU

clb bronzing symptoms-crop-u4018
Cercospora Leaf Blight Bronzing Symptoms
Photo Credit: Heather Kelly – UT

Close up of Blight Symptom
Close-up of Blight Symptoms
Photo Credit: Trey Price – LSU

purple seed stain - photo credit trey price lsu
Purple Seed Stain

Photo Credit: Trey Price – LSU

variety on right is suscept to clb-crop-u4045-1
Variety on Right is Susceptible to CLB

Photo Credit: Heather Kelly – UT