Disease scouting at harvest is often overlooked during a busy season, but it provides valuable insight into crop health and management decisions for future years. Pulling and assessing plants can help identify yield loss caused by specific diseases and highlight how variety selection and field practices performed throughout the season.
Why Scout for Disease?
Disease scouting during harvest acts as a proactive measure. According to BrettYoung Agronomic & Regulatory Services Manager Justine Cornelsen, pulling a few plants from different areas of the field ensures the whole field is represented. Examining each plant from the roots up can reveal a great deal about its health.
“Disease scouting is a task that can tell you a lot about your variety selection and management practices from the season,” said Cornelsen. “But it also provides valuable information to help you alter practices for future years.”
Many plant diseases create similar symptoms, such as premature ripening or plant lodging, so identifying signs of specific pathogens helps determine the true cause of damage. Reviewing environmental conditions can also help explain which diseases were most active in a given season.
Environmental Influence on Disease
Recent years of hot, dry summers have:
- Limited damage from sclerotinia
- Allowed verticillium stripe in canola to thrive
When to Scout Canola
Disease symptoms become more apparent as the crop approaches maturity. To get the most accurate assessment, plan to scout:
- Around 60% seed colour change (SCC) or swathing
- Closer to harvest when straight cutting, to better estimate yield loss from diseases such as sclerotinia and blackleg
Using Root and Stem Assessment
Examining roots and basal tissue can help differentiate between:
- Blackleg
- Verticillium stripe
- Root rot
Swollen roots (galls) are a clear sign of clubroot, which should trigger changes in rotation planning, hybrid selection, and sanitation protocols.
Key Diagnostic Indicators
- Blackleg: black spots or wedges in root cross-sections
- Verticillium stripe: greyish root tissue and later formation of microsclerotia in stems
- Sclerotinia vs. verticillium stripe: both bleach stems and make them fragile and prone to shredding
- Sclerotinia: sclerotia bodies form inside the stem
Additional Late-Season Diseases
- Powdery mildew: produces white dust but typically little yield impact
- Alternaria pod spot: speckled, weakened pods that may cause harvest challenges
When to Scout Soybeans
Scout soybeans between R5 and R6 to check for foliar and stem diseases such as:
- Bacterial blight
- Septoria brown spot
- Downy mildew
- Frogeye leaf spot
- Northern stem canker
- White mould
- Pod or stem blight
- Anthracnose
Root Issues to Watch For
Pulling plants can reveal:
- Soybean cyst nematode (SCN): tiny lemon-shaped cysts on roots
- Phytophthora root rot (PRR): brown stem lesions that restrict movement of water and nutrients
- These diseases can be managed through appropriate variety selection.
Disease Management
Although yield losses cannot be prevented at harvest, scouting results provide valuable information for:
- Future crop planning
- Product selection
- Understanding field-to-field yield differences
DefendR® Traits
When reviewing BrettYoung canola options, look for the DefendR® designation, indicating:
- Resistance to clubroot or blackleg
- Pod shatter tolerance
BrettYoung soybean varieties also contain defensive packages for:
- PRR
- White mould
- SCN
FAQ
Why is disease scouting during harvest important?
Disease scouting at harvest helps determine current yield losses due to diseases and provides valuable information for future crop management decisions.
What is the recommended timing for scouting canola for disease?
The best time to scout canola is at around 60% seed colour change or at swathing time to differentiate between plant diseases. For straight cutting, scouting should be done closer to harvest.
How can you distinguish between blackleg and verticillium stripe in canola?
Blackleg shows as black spots or wedges in the root cross section. Verticillium stripe leaves the root tissue a greyish hue and forms tiny microsclerotia in the plant stalk tissue.
What are some common diseases to watch for in soybeans at harvest?
Common diseases include bacterial blight, Septoria brown spot, downy mildew, frogeye leaf spot, northern stem canker, white mould, pod or stem blight and anthracnose.
What should growers look for to identify soybean cyst nematode (SCN)?
Growers should look for tiny, lemon-shaped cysts on the soybean plant roots that are smaller than nodules.
How can the information gathered from disease scouting be used?
The information collected helps guide future crop planning, product selections and explains differences in yield among fields and products.
What disease resistance traits are present in BrettYoung canola and soybean products?
BrettYoung canola hybrids with the DefendR designation have resistance to clubroot or blackleg and pod shatter tolerance. Soybean varieties offer resistance to PRR, white mould and SCN.
