Sclerotinia Stem Rot

Overview

Sclerotinia Stem Rot, caused by the fungus Sclerotinia sclerotiorum, is a significant disease affecting various crops in the US and Canada. This pathogen thrives in cool, moist conditions and can infect over 400 plant species, including soybeans, canola, sunflowers, and dry beans.

The disease manifests as white, cottony mycelium on stems, leaves, and pods, leading to wilting, stem breakage, and plant death. Sclerotinia Stem Rot can cause substantial yield losses, particularly in dense crop canopies where humidity is high. In soybeans, it can reduce yields by up to 50%, while in canola, losses can reach 20-30%.

Effective management includes crop rotation, resistant varieties, and timely fungicide applications. Products like Endura® fungicide (Boscalid) and Proline® 480 SC (Prothioconazole) are commonly used to control this disease. Early detection and integrated disease management strategies are crucial to mitigating the impact of Sclerotinia Stem Rot on crop productivity.

Photo Credit: Craig Grau, Bugwood.org

Sclerotinia Stem Rot 1

How to Identify Sclerotinia Stem Rot

Farmers can identify Sclerotinia Stem Rot using a few indicators:

  1. Visual Symptoms: Look for white, cottony mycelium on stems, leaves, and pods. This fungal growth is a key indicator of Sclerotinia Stem Rot. As the disease progresses, it can cause water-soaked lesions that turn tan to brown.

  2. Stem Inspection: Check the stems for signs of wilting and breakage. Infected stems often become soft and mushy, leading to plant collapse. The presence of hard, black sclerotia (fungal survival structures) inside the stem or on the soil surface is a definitive sign.

  3. Field Conditions: Note the environmental conditions. Sclerotinia Stem Rot thrives in cool, moist environments, particularly in dense crop canopies where humidity is high.

  4. Crop Impact: Observe the overall health of the crop. Infected plants may exhibit wilting, reduced vigor, and premature death, leading to significant yield losses.

By closely monitoring these symptoms and conditions, farmers can accurately identify Sclerotinia Stem Rot and take timely action to manage the disease.

Photo Credit: Barbara Shew, North Carolina State University, Bugwood.org

Barbara Shew, North Carolina State University, Bugwood.org

Geographic Impact of Sclerotinia Stem Rot

Sclerotinia Stem Rot has a broad geographic impact across the United States and Canada, affecting various regions based on climate and crop types.

  1. Midwest and Great Plains: These regions, known for extensive soybean and sunflower production, are particularly vulnerable. The cool, moist conditions during the growing season favor the development of Sclerotinia Stem Rot, leading to significant yield losses.

  2. Northeast and Great Lakes: The humid climate and frequent rainfall in these areas create ideal conditions for the disease. Crops like soybeans, dry beans, and canola are commonly affected.

  3. Southeast: While less prevalent due to generally warmer and drier conditions, Sclerotinia Stem Rot can still impact crops during periods of cool, wet weather, particularly in dense crop canopies.

  4. Western US: In states like California and the Pacific Northwest, the disease can affect a variety of crops, including vegetables and ornamentals, especially in irrigated fields where moisture levels are high.

  5. Canada: The disease is a significant concern in the Prairie Provinces (Alberta, Saskatchewan, and Manitoba), where canola and pulse crops are widely grown. The cool, wet conditions during the growing season are conducive to the development of Sclerotinia Stem Rot.

Understanding the geographic impact of Sclerotinia Stem Rot helps in tailoring specific management practices to local conditions, ensuring more effective control and mitigation of damage.

Timing of Sclerotinia Stem Rot Impact

Sclerotinia Stem Rot typically emerges and impacts fields across the US during periods of cool, moist conditions, which are most common in late spring to early summer. The disease thrives in environments with high humidity and dense crop canopies, making these times particularly critical for monitoring and management. Farmers should be vigilant during these periods, especially after prolonged wet weather, to detect early signs of the disease and implement control measures promptly.

Photo Credit: Barbara Shew, North Carolina State University, Bugwood.org

Barbara Shew, North Carolina State University, Bugwood.org

How to Manage Sclerotinia Stem Rot

Farmers can manage Sclerotinia Stem Rot through a combination of cultural practices, biological controls, and chemical treatments. Here are some specific strategies and examples of chemical products for different crops:

  1. Soybeans: Implement crop rotation and use resistant varieties to reduce disease pressure. Fungicides like Endura® fungicide, which contains Boscalid, can be effective.

  2. Canola: Maintain proper plant spacing to reduce humidity within the canopy. Proline® 480 SC, containing Prothioconazole, is a commonly used fungicide for managing Sclerotinia Stem Rot in canola.

  3. Sunflowers and Dry Beans: Similar to soybeans and canola, crop rotation and resistant varieties are crucial. While specific fungicides like Endura® fungicide and Proline® 480 SC are effective, always check the label for application rates and availability.

Every product that labels SCLEROTINIA STEM ROT as a weed, pest, or disease the product can be applied against is shown below. Click any product for label and more information.
A-Zox 25SCAcadia™ 2 SCAcadia™ 2 SCAcropolis FungicideAcropolis™ FungicideActinovate® AGActinovate® AGAffiance®Affiance™Aframe™Amplitude™Andiamo® 230 FungicideAndiamo™ 230 FungicideAndiamo™ AdvanceAproach®Arius™ ADV FungicideArius™ AdvanceAviv™Aviv™AzoxyStar®Azoxystrobin SCAZterknot®AZteroid® FCAZteroid® FC 3.3BacixBallad® PlusBonafideBotryStop® WPBotryStop™Brixen™ FungicideBrixen™ FungicideCabrio® EG fungicideDelaro® 325 SC FungicideDelaro® CompleteDexter® SCDomark® 230 MEDomark® 230 ME FungicideEmpireEndura® fungicideEquation™Equation™ SC FungicideFontelis®Fortix® FungicideFungo® FloGCS Azoxy 2SCGold Rush®Guarda®Howler® EVOHowler® FungicideIncognito® 85 WDGKenja® 400SC FungicideLuna Experience®Luna Sensation®Luna® FlexLuna® PrivilegeMazinga™ ADV FungicideMazinga™ ADV FungicideMazolin™Meteor® FungicideNevado® 4FNufarm T-Methyl 70 WSB FungicideObrona™Omni® Brand T-Methyl 70 WPPalladium®Phoenix™ HerbicidePreemptor™ SC FungicidePriaxor® D {Component B}Priaxor® D fungicidePriaxor® Xemium® brand fungicidePristine® fungicideProline® 480 SCPropulse®Prozio™ SCQuadris® FlowableQuash® FungicideQuash® SC FungicideRegalia®Revytek™ fungicideSatori® FungicideSerenade® ASOSerenade® MAXSerenade® OptiSerenade® OptimumSerifel® BiofungicideSonata®Stargus™Talaris™ 50 WSPTalaris™ 70 WSBTepera® PlusTepera® Plus HDTepera® Plus HDTesaris™ fungicideTetraban®Tetraban® FungicideThiophanate Methyl 85 WDGTopguard®Topguard® FungicideTopsin® M WSB FungicideTrevo®Trevo® TRZVacciplant®Vacciplant®Velum®Velum® PrimeVertisan®Willowood Azoxy 2SCZolera™ FX Fungicide