Diplodia Stalk Rot of Corn
Published: 01/27/2022
Diplodia stalk rot is caused by the fungus Stenocarpella maydis. Plants affected by Diplodia stalk rot have shredded pith and die prematurely. Numerous black dots, about the size of a pinhead or smaller, can be observed in the lower internodes of the stalk. Under very wet conditions, a white mold may develop on the stalk surface.
Infections occur through the crown, roots, mesocotyl, and lower nodes. Insects possibly carry the spores and introduce them into feeding wounds. Diplodia stalk rot is favored by dry conditions early in the season followed by warm, wet conditions after silking. The disease is more prevalent in corn following corn.
There are hybrids available with good resistance to Diplodia stalk rot. Rotation and tillage can reduce inoculum.
Shredded pith from Diplodia stalk rot.
Image: A. Robertson
Diplodia stalk rot can result in small black pycnidia on the lower internodes that are not easily scraped off.
Image: G. Munkvold
Signs of Diplodia stalk rot include pycnidia on lower internodes.
Shredded pith from Diplodia stalk rot.
Pycnidia, a fungal fruiting structure, cannot easily be scraped off.
Small, black pycnidia on the stalk cannot easily be scraped off.
Stalk lodging from Diplodia stalk rot.
Diplodia stalk rot can result in small black pycnidia on the lower internodes.
Gallery Images: A. Robertson and G. Munkvold
This publication was developed by the Crop Protection Network, a multi-state and international collaboration of university/provincial extension specialists and public/ private professionals that provides unbiased, research-based information to farmers and agricultural personnel.
This information in this publication is only a guide, and the authors assume no liability for practices implemented based on this information. Reference to products in this publication is not intended to be an endorsement to the exclusion of others that may be similar. Individuals using such products assume responsibility for their use in accordance with current directions of the manufacturer.
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual's income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA's TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD).
USDA is an equal opportunity provider and employer.
©2022 by the Crop Protection Network. All rights reserved.
