Understanding QoI Fungicides in Modern Agriculture
Strobilurin fungicides, also known as QoI fungicides (Quinone outside Inhibitors), have become essential tools in protecting high-value crops from fungal diseases. Among them, Azoxystrobin and Pyraclostrobin are two of the most widely used active ingredients globally.
While both belong to the FRAC Group 11, and share a similar mode of action by inhibiting mitochondrial respiration in fungal cells, they exhibit notable differences in residual activity, spectrum of control, systemic movement, and formulation compatibility. Understanding these differences is critical for making informed decisions in integrated disease management programs.
1. What Is Azoxystrobin?
Azoxystrobin is a broad-spectrum, systemic fungicide that has been widely adopted in crop protection for its long residual activity and preventive capabilities.
Key Characteristics:
Mode of Action: Inhibits electron transport at the Qo site in Complex III of mitochondria (FRAC 11)
Translocation: Xylem-mobile; translaminar movement
Systemicity: True systemic activity—can move through plant tissues
Target Diseases: Rusts, powdery mildew, leaf spots, downy mildew, blights
Crops: Used in cereals, vegetables, fruits, turfgrass, and ornamentals
Azoxystrobin’s advantage lies in its preventive efficacy and long-lasting protection, making it ideal for early-season disease control or programs requiring fewer applications.
2. What Is Pyraclostrobin?
Pyraclostrobin is another QoI fungicide, valued not only for its strong protective activity but also for its plant health benefits, including increased stress tolerance and crop vigor.
Key Characteristics:
Mode of Action: Same FRAC 11 mechanism—mitochondrial respiration inhibition
Translocation: Translaminar; locally systemic
Systemicity: Limited; not fully systemic like Azoxystrobin
Target Diseases: Anthracnose, rusts, leaf spots, scab, Sclerotinia, Alternaria
Crops: Soybeans, corn, potatoes, vegetables, tree nuts
Pyraclostrobin is often chosen for its curative effect and physiological benefits, including improved photosynthesis and drought resistance when applied under stress-prone conditions.
3. Azoxystrobin vs Pyraclostrobin: Comparison Table
Feature
Azoxystrobin
Pyraclostrobin
Fungicide Class
Strobilurin (QoI)
Strobilurin (QoI)
FRAC Code
11
11
Systemicity
Fully systemic
Locally systemic
Translocation
Xylem-mobile, translaminar
Translaminar only
Preventive Activity
Strong
Strong
Curative Activity
Moderate
Slightly stronger
Disease Spectrum
Broad (rusts, downy mildew, blights)
Broad (scab, Sclerotinia, leaf spots, rusts)
Residual Duration
Long (up to 21 days)
Moderate (10–14 days)
Plant Health Benefits
Moderate
Strong (increased vigor, drought tolerance)
4. Application Considerations: When to Use Which?
Choose Azoxystrobin when:
You need long-lasting residual control (e.g., in corn or wheat)
You’re applying early in the disease cycle as a preventive measure
You need systemic movement within the plant
Used in turf and ornamentals for broad coverage and longevity
Choose Pyraclostrobin when:
Your crop is under abiotic stress, like heat or drought
You seek both disease control and physiological enhancement
You require stronger curative activity
Used in soybeans and potatoes where vigor response is key
In many fungicide programs, Azoxystrobin and Pyraclostrobin are rotated or combined with other modes of action to improve disease control and delay resistance development.
5. Resistance Management and Tank Mix Strategies
Both Azoxystrobin and Pyraclostrobin are prone to resistance if used repeatedly as solo products due to their single-site mode of action. To manage resistance:
Rotate with fungicides from different FRAC groups, such as triazoles (FRAC 3), SDHIs (FRAC 7), or multi-site protectants like chlorothalonil (FRAC M5)
Use as a premix or tank-mix partner with complementary products
Follow label restrictions on number of sequential applications
Common commercial combinations include:
Azoxystrobin + Difenoconazole
Pyraclostrobin + Fluxapyroxad (for soybeans and corn)
Azoxystrobin + Chlorothalonil (for vegetables and turf)
Pyraclostrobin + Boscalid (for broad-spectrum control in leafy crops)
6. Conclusion: Azoxystrobin vs Pyraclostrobin – Which Is Right for You?
Both Azoxystrobin and Pyraclostrobin are leading strobilurin fungicides with overlapping but distinct profiles. While Azoxystrobin offers broader translocation and longer-lasting control, Pyraclostrobin brings plant health enhancement and stronger stress-response benefits.
Key Takeaway:For long residual, systemic movement, and early disease prevention—Azoxystrobin is often preferred.For short-term control, curative action, and improved crop vigor—Pyraclostrobin is a smart choice.
Selecting the right product—or a combination of both—depends on your crop, disease pressure, application timing, and overall program design.
Are You Looking for High-Quality Fungicide Formulations?
We supply a full portfolio of strobilurin fungicides, including:
Azoxystrobin SC, WG, and OD formulations
Pyraclostrobin SC and WDG
Custom premixes, OEM/ODM services, and global export packaging
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