Pod Blight

Overview

Pod and stem blight, a fungal disease caused by Diaporthe phaseolorum, can cause substantial yield loss, particularly when environmental conditions favor its proliferation.

Clemson University - USDA Cooperative Extension Slide Series , Bugwood.org

The fungus primarily infects the stems and pods of soybean plants. Infected stems weaken and may break easily, leading to lodging and complicating harvest. Infected pods often contain shriveled, low-quality seeds, significantly reducing yield.

The fungus can also disrupt the plant's physiology. It impedes the plant's vascular system, hindering the transport of water and nutrients. This can lead to wilting, defoliation, and premature plant death.

Furthermore, the fungus produces toxins that can cause additional damage to plant tissues. These toxins can contaminate the seeds, reducing their quality and market value.

(Image Credit: Clemson University - USDA Cooperative Extension Slide Series , Bugwood.org)

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How to Identify Pod and Stem Blight

Pod and stem blight manifests through several key symptoms, which differ based on the plant's growth stage.

The most distinctive symptom of pod and stem blight is the emergence of small, black, elongated lesions on the stems, pods, and petioles. These lesions are the fungus's reproductive structures, known as pycnidia. They often arrange themselves in rows or bands, creating a rough, sandpaper-like texture on the stem.

In the early stages, the disease may induce wilting and yellowing of leaves. As it advances, it can cause premature defoliation and plant death. Infected pods typically contain shriveled seeds, possibly covered with a chalky, white mold.

(Image Credit: Gerald Holmes, Strawberry Center, Cal Poly San Luis Obispo, Bugwood.org)

pod-stem-blight-soybeans1

Geographic Impact of Pod and Stem Blight

Pod and stem blight has been reported in nearly all soybean-growing regions worldwide. However, it is more common in warm, humid climates.

The disease is most likely to occur when frequent rainfall accompanies the late growing season. It is also more prevalent in fields with a history of soybean cultivation, as the fungus can survive in infested crop residues.

Timing of Pod and Stem Blight

The disease can infect soybean plants at any growth stage, but symptoms are most visible during the late vegetative and reproductive stages. The fungus can infect seedlings, but symptoms often remain unnoticed until the late growing season when plants are under stress.

How to Manage Pod and Stem Blight in Soybeans

Pod and stem blight is a complex disease caused by many closely related species of fungi. Fungicides can help reduce disease, but yields may not be completely protected.

To manage pod and stem blight in soybeans, our agronomists recommend using Trivapro® during the R5 growth stage.

Disclaimer

© 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.

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