Protecting crop potential means acting early, guided by an understanding of pathogen biology, infection timing, and real-world fungicide performance.
Here’s a focused look at the most impactful diseases to canola, sugarbeet, wheat, and dry beans, and how to stay ahead of them:
Canola
Key diseases and agronomic impact
- Sclerotinia Stem Rot or White Mold (Sclerotinia sclerotiorum): Resulting in white, bleached lesions on stems and leaves, Sclerotinia stem rot thrives in dense, humid canopies. Causes premature ripening, lodging, and significant yield loss once stems are infected.
Management Strategies
- Rotate crops (2–3 years) to reduce inoculum
- Manage canopy density to limit humidity and leaf wetness
- Time fungicides precisely:
- Early season for blackleg
- Podding stage for Alternaria
- 20–30% bloom for Sclerotinia
Phobos® FC fungicide protects from yield-robbing disease by delivering even, reliable disease control. Due to its Advanced Application Advantage, Phobos® FC dries stronger where it is applied, achieving twice the leaf coverage and significantly reducing rain wash off compared to the leading competitor which tends to ridge and clump together causing unreliable performance. In trials, applications timed at 20% bloom followed by an application at 50% bloom produced the best results for Sclerotinia control.
Sugarbeets
Key disease and agronomic impact
- Cercospora Leaf Spot (Cercospora beticola): Developing small, circular spots with ash-gray centers and dark brown to reddish-purple borders, Cercospora leaf spot (CLS) is the most damaging disease for sugarbeets. It reduces yield and sugar production by causing defoliation and forcing repeated leaf regrowth.
- Powdery Mildew (Erysiphe betae): Known for its white, talcum-powder-like patches on both the upper and lower surfaces of leaves, Powdery mildew reduces photosynthesis late in the season, limiting sugar accumulation.
Management strategies
- Rotate crops (3+ years) with non-hosts (corn, wheat, soybeans)
- Choose tolerant varieties such as CR+ for Cercospora leaf spot
- Residue Management: Utilize deep tillage to bury infected residue, and select fields distanced from previously infected fields when planting.
- Cultural Practices: Adopt cultural practices that promote optimal plant health and vigor, such as balanced fertility management, proper irrigation scheduling, and weed control.
- Apply fungicides early and proactively: With increasing CLS pressure in 2025, and more expected this year, Phobos® FC has demonstrated enhanced control of CLS compared to the leading competitor, helping preserve both yield and sugar content. Phobos FC spreads more uniformly and lasts longer on the leaf surface, providing consistent protection and decreased rain wash off. An early application of Phobos FC gives sugarbeets a clean start for disease prevention, while a second, late-season application provides a strong finish to maximize yield and sugar quality.
Wheat
Key diseases and agronomic impact
- Septoria tritici blotch (Zymoseptoria tritici): Causes tan, necrotic lesions on leaves, and progressively destroys leaf area, especially damaging when it reaches the flag leaf.
- Tan Spot (Pyrenophora tritici-repentis): Characterized by its tan-colored spots with yellow halos, and commonly associated with wheat residue, tan spot reduces early vigor and green leaf area.
- Leaf Rust (Puccinia triticina): The most common rust, appearing as small, powdery, reddish-orange pustules on leaves, causes premature leaf death and the shortening of grain fill.
- Fusarium Head Blight (Fusarium graminearum): Infected spikelets turn white or grey, infected kernels are shrunken and wrinkled, and salmon-orange or pink, fluffy fungus may be visible at the base of the glumes. Fusarium head blight impacts yield, grade, and safety through DON contamination.
Management strategies
- Crop Rotation: A minimum of one year rotation to a non-host crop (canola, corn, soybeans) can help reduce septoria and tan spot, which are residue-borne diseases.
- Protect key growth stages:
- T1 (stem elongation): suppress early season disease
- T2 (flag leaf): critical for yield protection against foliar diseases such as rusts with a low risk of Fusarium head blight
- Time fungicides precisely: For Fusarium head blight and scab, the recommended fungicide spray application timing for Phobos® FC is at anthesis when the anthers are starting in the middle of the head. This timing will support key leaf disease control, allowing for a clean flag leaf to drive yield through harvest.
Dry beans
Key diseases
- White Mold (Sclerotinia sclerotiorum): Characterized by fluffy white fungal growth on stems and pods, followed by the formation of hard, black sclerotia, white mold thrives in dense canopies and moist conditions. It can cause significant yield loss through plant death and poor pod fill.
- Rhizoctonia Root Rot (Rhizoctonia solani): A soilborne pathogen that causes reddish-brown lesions on roots and hypocotyls, leading to damping-off, poor emergence, and stunted growth. Infection is often worse in cool, wet soils and compacted conditions, resulting in uneven stands and reduced yield potential.
- Ascochyta Blight (Ascochyta pinodes): Characterized by dark, sunken lesions on leaves, stems, and pods, often with concentric rings. This disease thrives in wet, humid conditions and can lead to defoliation, pod infection, and reduced seed quality.
- Rust (Uromyces appendiculatus): Identified by small, reddish-brown pustules on leaves, stems, and pods that release powdery spores. Severe infections can cause premature leaf drop, reduce photosynthetic capacity and ultimately impact yield.
Management Strategies
- Rotate crops (2–3+ years) with non-hosts (corn or cereals) to reduce pathogen carryover.
- Select disease-tolerant or resistant varieties, particularly for white mold and bacterial blights.
- Optimize canopy management by adjusting row spacing and seeding rates to improve airflow and reduce humidity within the canopy.
- Promote overall plant health through balanced fertility, proper irrigation timing (avoiding prolonged leaf wetness), and effective weed control to reduce disease pressure.
- Apply fungicides preventatively, such as AZterknot® and Phobos® FC at planting for Rhizoctonia control. For mid-season foliar protection, utilize Phobos FC. It dries stronger on the leaf delivering uniform leaf coverage and reduced wash off, providing broad-spectrum control of key foliar diseases such as Asochyta Blight, Rust, and White mold. AZterknot spreads flat, sticks, and stays on the leaf surface when applied foliarly, providing wide-spread control of Rust, Alternaria blight and leaf spot, Anthracnose, and more.
Conclusion
Foliar disease management requires a systems-based approach that integrates agronomy, pathogen biology, and fungicide technology. While disease pressure cannot be eliminated, its impact can be significantly reduced through precise, proactive management.
Learn more about how Phobos® FC and Vive’s other foliar solutions can protect your yield potential and crop quality.
Important: Always read and follow label directions. AZterknot®, Phobos®, Precision Chemistry™, and the Vive logo are registered trademarks of Vive Crop Protection. ©2026 Vive Crop Protection, Inc.
