Diplodia stalk rot, a disease instigated by the fungus Stenocarpella maydis, can cause stalk rot, leaf blight and ear rot, resulting in up to 50% yield loss in severe cases.

The disease can weaken the stalk, making the plant susceptible to lodging. It can also hinder the plant's ability to transport water and nutrients, leading to premature death, and disrupt the plant's ability to fill the kernels, resulting in lightweight, chaffy, and overall poor quality grain.

How to Identify Diplodia Stalk Rot

The onset of Diplodia stalk rot is marked by the premature death of the plant. The leaves transition to a dull gray-green color before wilting and drying up. The lower internodes of the stalk soften and turn a tan to brown color, while the stalk's pith discolors and disintegrates, leaving only the vascular bundles.

When you split the stalk, you may observe a white to pinkish mold growing between the nodes, particularly at the stalk's base. Tiny, black fungal structures called pycnidia can be found scattered on the lower internodes and on the outer husks of the ear. These pycnidia serve as a key diagnostic feature of the disease.

To ascertain the presence of Diplodia stalk rot, conduct a simple test. Place the suspected stalk or ear in a plastic bag with a wet paper towel and seal it. If Diplodia is present, white mold will develop within 24 to 48 hours.

Geographic Impact of Diplodia Stalk Rot

While Diplodia stalk rot is most common in the Midwestern United States, it can strike wherever corn grows. It is more prevalent in areas with high humidity and rainfall.

Timing of Diplodia Stalk Rot

Diplodia stalk rot can infect corn at any growth stage, but symptoms typically emerge after tasseling. The disease intensifies during and after silking in years with wet weather.

The disease intensifies in continuous corn fields and fields where corn residue remains on the surface, as the fungus overwinters in this residue and infects the subsequent crop.

How to Manage Diplodia Stalk Rot in Corn

Choose corn hybrids with higher stalk integrity and standability ratings to help protect crops. 

Fungicides aren't effective against Diplodia stalk rot itself, but they can help protect overall plant and stalk health. Fungicide applications near tassel timing — or earlier if disease or environmental threats warrant — can help protect stalk integrity. Protect stalk integrity by managing foliar diseases with a fungicide like GCS Azoxyprop or Willowood Teb 3.6SC

Similarly, controlling insects that can wound plant tissue can help reduce the entry of fungal pathogens into the plant. Overall, hybrid product selection and keeping the crop as healthy as possible with a comprehensive crop protection program are the best defenses against Diplodia stalk rot. Ensure sufficient crop nutrition with fertilizers like Nourish Vitals™ or Inhabit N™

Apply insecticides for stalk borer larvae when they begin migrating to cornfields. Insecticides are only effective if larvae are controlled before they enter the corn stalk. Control stalk-boring insects with insecticides like Asana XL**, GCS Bifenthrin 2EC**, or Willowood Lambda-Cy 1EC** to prevent tissue wounds where fungal spores can enter. 

Always follow the label instructions and consult with your local agricultural extension or a certified agronomist for specific recommendations based on your field conditions and the severity of the Diplodia stalk rot.

GCS Azoxyprop tote 800x800


© 2014 - 2023 Farmer's Business Network, Inc. All rights Reserved. The sprout logo, “Farmers Business Network”, “FBN”, “FBN Direct” are trademarks or registered trademarks of Farmer's Business Network, Inc. This content was written by Norm℠, reviewed and edited by Mikaela Tierney.

This content was generated with the assistance of Norm℠, FBN’s artificial intelligence (AI) Ag Advisor, based on a dataset of information containing general industry best practices and research. The AI model did not use specific external sources to generate this content. Our process involves using AI to aid human subject matter experts with the initial drafting and/or refinement of content.

The information and content provided is believed to be reliable, but its accuracy is not guaranteed. The content is provided for informational purposes only. It is not intended to be a substitute for specific agronomic, business, or professional advice, and should not be relied upon as such. Neither Farmer's Business Network Inc. nor any of its affiliates makes any representations or warranties, express or implied, as to the accuracy or completeness of the statements or any information contained in the material and any liability therefore is expressly disclaimed. If you have any questions or feedback about the content, please feel free to contact us or visit our FAQ (https://www.fbn.com/community/blog/norm-faq).

Asana®  is a registered trademark of Sumitomo Chemical Company, Ltd.

All other trademarks are the property of their respective owners.

**Asana® XL is a restricted use pesticide.

**GCS Bifenthrin 2EC is a restricted use pesticide.

**Willowood Lambda-Cy 1EC is a restricted use pesticide.

**RESTRICTED USE PESTICIDE Due to acute toxicity. For retail sale to and use by certified applicators only – NOT to be used by uncertified persons working under the supervision of a certified applicator.

ALWAYS READ AND FOLLOW LABEL DIRECTIONS. It is a violation of federal and state law to use any pesticide product other than in accordance with its label. The distribution, sale and use of an unregistered pesticide is a violation of federal and/or state law and is strictly prohibited. We do not guarantee the accuracy of any information provided on this page or which is provided by us in any form. It is your responsibility to confirm prior to purchase and use that a product is labeled for your specific purposes, including, but not limited to, your target crop or pest and its compatibility with other products in a tank mix and that the usage of a product is otherwise consistent with federal, state and local laws.  We reserve the right to restrict sales on a geographic basis in our sole discretion. You must have a valid applicator license to use restricted use pesticides.  Please consult your state department of agriculture for complete rules and regulations on the use of restricted use pesticides, as some products require specific record-keeping requirements.

All product suggestions and other information provided is for informational purposes only. It is not intended to be a substitute for consulting the product label or for specific agronomic, business, or professional advice. Where specific advice is necessary or appropriate, consult with a qualified advisor. Neither Farmer's Business Network Inc. nor any of its affiliates makes any representations or warranties, express or implied, as to the accuracy or completeness of the statements or any information contained in the material and any liability therefore is expressly disclaimed.

Every product that labels DIPLODIA as a weed, pest, or disease the product can be applied against is shown below. Click any product for label and more information.
Aframe™GCS Azoxy 2SCPhyton® 27Phyton® 35Spectro® 90 WDGTepera® PlusTepera® Plus HDTepera® Plus HD