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How to Identify Crown Rot

Identifying crown rot in crops involves careful observation of several specific symptoms and signs. Here’s a detailed guide to help farmers recognize this disease:

Initial Symptoms:
- Discoloration: Look for a light brown to dark brown discoloration at the base of the stem, just above the soil line. This is often the first visible sign of crown rot.
- Lesions: Check for lesions or necrotic spots on the lower stem and crown area. These lesions may expand and coalesce, leading to extensive browning.
Plant Growth:
- Stunted Growth: Affected plants often exhibit stunted growth compared to healthy plants. They may appear shorter and less vigorous.
- Reduced Tillering: In cereals like wheat and barley, crown rot can cause a noticeable reduction in the number of tillers (side shoots).
Root System:
- Root Decay: Dig up a few plants and examine the root system. Infected plants typically have a decayed or rotted root system, which is often brown and brittle.
- Poor Root Development: The roots may be poorly developed and show signs of necrosis.
Foliage Symptoms:
- Yellowing and Wilting: The leaves of infected plants may turn yellow and wilt, especially during periods of water stress.
- Premature Senescence: In severe cases, the entire plant may die prematurely, leading to early senescence.
Field Patterns:
- Patchy Distribution: Crown rot often appears in patches within a field, rather than uniformly. These patches may correspond to areas with poor drainage or previous crop residues.
Microscopic Examination:
- Fungal Structures: For a definitive diagnosis, collect samples and send them to a diagnostic lab. Under a microscope, the presence of Fusarium spores and mycelium can confirm crown rot.
Environmental Conditions:
- Weather Patterns: Consider recent weather conditions. Crown rot is more prevalent in warm, moist environments, especially following wet springs and dry summers.

By closely monitoring these symptoms and considering environmental factors, farmers can accurately identify crown rot and take appropriate management actions. Early detection is crucial for effective control and minimizing yield losses.

Geographic Impact of Crown Rot

Crown rot has a significant geographic impact, affecting various regions across the United States and Canada, particularly in areas where environmental conditions favor the disease. Here’s a detailed look at its geographic impact:

United States:

Great Plains:
- States Affected: Kansas, Nebraska, Oklahoma, Texas.
- Crops: Wheat and barley are major crops in this region, and crown rot is a common issue due to the warm, dry conditions that can follow wet springs.
Pacific Northwest:
- States Affected: Washington, Oregon, Idaho.
- Crops: This region is known for its wheat and barley production. The disease thrives in the cool, wet springs followed by dry summers typical of this area.
Midwest:
- States Affected: North Dakota, South Dakota, Minnesota.
- Crops: Wheat, barley, and legumes are commonly affected. The disease can be exacerbated by the region's variable weather patterns.
Southern States:
- States Affected: Arkansas, Louisiana, Mississippi.
- Crops: Corn and soybeans are also susceptible to crown rot, especially in the warm, humid conditions prevalent in these states.

Canada:

Prairie Provinces:
- Provinces Affected: Alberta, Saskatchewan, Manitoba.
- Crops: Wheat and barley are major crops here. The disease is a significant concern due to the region's dry summers following wet springs.
Eastern Canada:
- Provinces Affected: Ontario, Quebec.
- Crops: Corn and soybeans are commonly affected. The disease can be problematic in the humid conditions typical of this region.

Environmental Conditions:

Temperature: Crown rot is more prevalent in regions with warm temperatures, particularly where there are significant temperature fluctuations between seasons.
Moisture: Areas with wet springs followed by dry summers are particularly susceptible, as the initial moisture promotes fungal growth, and the subsequent dryness stresses the plants, making them more vulnerable.

Timing of Crown Rot Impact

Crown rot typically emerges and impacts fields across the United States at specific times of the growing season, influenced by environmental conditions and crop growth stages. Here’s a detailed timeline of when crown rot is most likely to emerge and affect fields:

Emergence and Initial Infection:

Spring (Planting to Early Growth):
- Conditions: Crown rot fungi, primarily Fusarium species, thrive in moist soil conditions. Wet springs provide an ideal environment for the initial infection.
- Infection Timing: The fungi infect the seedlings and young plants during the early growth stages, particularly from planting through tillering in cereals like wheat and barley.

Disease Development:

Late Spring to Early Summer (Vegetative to Early Reproductive Stages):
- Conditions: As temperatures rise and soil moisture levels fluctuate, the disease begins to develop more aggressively. Warm, dry conditions following a wet spring can stress the plants, making them more susceptible to the disease.
- Symptoms: Initial symptoms such as browning at the base of the stem and reduced tillering become more noticeable during this period.

Peak Impact:

Mid to Late Summer (Reproductive to Maturity Stages):
- Conditions: The disease reaches its peak impact during the reproductive stages of the crop, including heading and grain filling in cereals.
- Symptoms: Severe symptoms such as stunted growth, yellowing and wilting of leaves, and premature senescence are most evident. The root system may show significant decay, and the overall plant health deteriorates.
- Yield Impact: This is the critical period when crown rot can cause substantial yield losses, as the disease interferes with nutrient and water uptake during the crucial grain-filling stage.

How to Manage Crown Rot

Farmers can manage crown rot in various crops through an integrated approach that includes cultural practices, crop rotation, resistant varieties, and the use of fungicides. Here are some specific strategies and examples of chemical products available for purchase from FBN:

Cultural Practices:

Crop Rotation: Rotate crops with non-host species to reduce the buildup of Fusarium pathogens in the soil.
Residue Management: Remove or deeply incorporate crop residues to minimize the source of inoculum.
Proper Irrigation: Avoid over-irrigation and ensure good drainage to reduce soil moisture levels that favor fungal growth.

Resistant Varieties:

Plant Resistant Varieties: Use crop varieties that are resistant or tolerant to crown rot to reduce disease incidence and severity.

Fungicide Applications:

Fortuna™ 75 WDG Fungicide:
- Active Ingredient: Mancozeb
- Crops: Labeled for use on wheat, barley, and legumes.
- Usage: Apply
  Fortuna™ 75 WDG Fungicide to protect crops from crown rot. It is effective in preventing the disease when used as part of a comprehensive management plan.
Thiophanate-methyl 4.50 Value Pick:
- Active Ingredient: Thiophanate-methyl
- Crops: Based on similarity with labeled products, it may be labeled for use on wheat, barley, and legumes.
- Usage: Thiophanate-methyl 4.50 Value Pick can be used to manage crown rot by applying it during the early growth stages to protect young plants from initial infection.

Timing and Application:

Early Detection: Monitor fields regularly for early symptoms of crown rot and apply fungicides at the first sign of disease.
Application Timing: Fungicides should be applied during the early growth stages, particularly from planting through tillering in cereals, to protect the plants from initial infection.

By combining these strategies, farmers can effectively manage crown rot and minimize its impact on crop yields.

Legal Disclosure

© 2014 - 2024 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.

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Crown Rot

Overview

Willowood Teb 3.6SC

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Thiophanate-methyl 4.50 Value Pick

Thiophanate-methyl 4.50 Value Pick

Currently unavailable

Fortuna™ 75 WDG Fungicide

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How to Identify Crown Rot

Geographic Impact of Crown Rot

United States:

Canada:

Environmental Conditions:

Timing of Crown Rot Impact

Emergence and Initial Infection:

Disease Development:

Peak Impact:

How to Manage Crown Rot

Cultural Practices:

Resistant Varieties:

Fungicide Applications:

Timing and Application:

Legal Disclosure

Notification

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