Diplodia Stalk Rot

Symptoms of Diplodia Stalk Rot

• Symptom:
• Diplodia stalk rot may first be evident when affected plants die suddenly during mid- to late-ear fill.
• Upon examination, dark brown lesions can be found extending in either direction from the node.
• Small black spots (pycnidia) may develop just beneath the stalk epidermis near the nodes. The black dots are not easily removed, which distinguishes Diplodia from Gibberella.
• Diplodia results in rotted stalks that are disintegrated and discolored (brown), allowing the stalk to be crushed or easily broken.
• Although the pith disintegrates, vascular bundles remain intact

• Diplodia Stalk Rot Facts:
• Caused by Stenocarpella maydis fungus (formerly called Diplodia maydis)
• Corn is the only host of this pathogen
• Survives on corn stalk residues
• Spores are spread by wind or splashing rain
• Favored by warm, wet weather two to three weeks after pollination

• Management:
• Genetic resistance – choose hybrids with high scores for stalk strength
• Crop rotation – at least one year out of corn
• Tillage to help break down crop residue
• Maintain balanced fertility
• Use moderate plant population if field has a history of stalk rot or lodging
• Reduce plant stress if possible
• Control stalk-boring insects to prevent wounds stalk rot organisms can enter.
• Pioneer® brand hybrids with Herculex® I or Herculex Xtra Insect Protection traits give excellent control of European and southwestern corn borer.