Stunner Cyazofamid 34.5% SC Fungicide - Downy Mildew & Late Blight Control by Insecticides India Ltd

Stunner is a specialized fungicide from Insecticides (India) Limited (IIL), containing Cyazofamid 34.5% SC (Suspension Concentrate). It is a "Make in India" product designed specifically to combat Oomycete diseases—commonly known as "water molds"—that cause devastating losses in high-value crops. Stunner is the first time this technical formulation has been manufactured in India, reducing farmer dependence on imported fungicides.

Stunner is highly effective against Downy Mildew in Grapes (caused by Plasmopara viticola) and Late Blight in Potatoes and Tomatoes (caused by Phytophthora infestans). These diseases can cause plant mortality ranging from 20% to 80%, severely affecting both yield and quality. Stunner belongs to the Cyanoimidazole chemical group and is classified under FRAC Group 21 (QiI Fungicide), offering a unique mode of action that makes it an effective resistance-breaking tool. It carries a Blue Triangle toxicity label (moderately toxic) and is available in a 40 ml pack size.

What makes Stunner particularly valuable for Indian farmers is its suitability for export-quality grape production, especially for grapes bound for the European Union, as Cyazofamid has a favorable Maximum Residue Limit (MRL) profile. It is also safe for honeybees, making it suitable for use during pollination periods. With rapid rainfastness (1 to 4 hours) and long-lasting protection (7 to 10 days), Stunner is a reliable choice even during the monsoon season.

Key Benefits

• Resistance breaker: Works effectively on fungal strains that have become resistant to older chemicals like Strobilurins or Phenylamides, thanks to its unique Qi-site mode of action
• Rapid rainfastness: Becomes rainfast within 1 to 4 hours after application, saving you from re-spraying costs if rain occurs shortly after spraying
• Long-lasting protection: Provides a solid defense shield for 7 to 10 days, reducing the total number of sprays needed per season
• Translaminar action: Penetrates the leaf surface to kill hidden fungus on the underside of leaves, ensuring complete coverage
• Export-safe for grapes: Meets strict EU residue limits (MRLs), making it suitable for export-quality grape production
• Bee-safe: Non-toxic to honeybees, so it can be used safely during pollination periods
• Anti-sporulant action: Prevents the fungus from releasing new spores, halting disease spread to neighboring plants
• First indigenous Indian manufacturing: Reduces dependence on imported fungicide formulations for grape cultivation

How It Works

Stunner operates through a unique and targeted mode of action that differs from standard fungicides. It targets the mitochondria—the energy-producing powerhouse—of the fungal cell. Specifically, Cyazofamid inhibits the Qi site of Complex III in the mitochondrial electron transport chain. This instantly stops the fungus from producing ATP (adenosine triphosphate), which is its primary energy source. Without energy, the fungal cells cannot survive, grow, or reproduce.

Because Stunner attacks the Qi site (ubiquinone-reducing site) rather than the Qo site (ubiquinol-oxidizing site) targeted by Strobilurins, there is no cross-resistance with older fungicide groups. This makes it highly effective against resistant fungal strains.

Stunner has three key effects on Oomycete pathogens: First, it paralyzes zoospores—the swimming spores that spread Oomycetes through water films on leaves and soil. By cutting their energy supply, these zoospores become immobile and cannot infect new leaves or tubers. Second, it acts as a powerful anti-sporulant, preventing the fungus from releasing new spores and stopping the disease from spreading to neighboring plants. Third, its translaminar action allows it to penetrate the leaf tissue and reach the underside, where fungal growth often remains hidden from contact sprays.

Technical Specifications

Parameter	Details
Brand Name	Stunner
Manufacturer	Insecticides (India) Limited (IIL)
Technical Name	Cyazofamid 34.5% SC
Formulation Type	Suspension Concentrate (SC)
Chemical Group	Cyanoimidazole
FRAC Mode of Action Code	Group 21 (QiI Fungicide)
Toxicity Label	Blue Triangle (Moderately Toxic)
Appearance	White to off-white suspension
pH (at 27°C)	6.0 to 7.5
Density at 20°C	1.16 ± 0.02
Suspensibility	Minimum 60% w/w
Pack Size	40 ml

Recommended Dosage & Application

Crop	Target Disease	Dose (ml/Acre)	Water (L/Acre)	Dose (ml/Litre)	PHI (Days)
Grape	Downy Mildew (Plasmopara viticola)	80 ml	200 - 400 L	0.2 - 0.4 ml/L	Use before fruit pruning / Check export limits
Potato	Late Blight (Phytophthora infestans)	80 ml	200 L	0.4 ml/L	7 Days
Tomato	Late Blight (Phytophthora infestans)	80 ml	200 - 250 L	0.4 ml/L	3 - 7 Days

Note: PHI = Pre-Harvest Interval — the minimum number of days to wait between the last spray and harvesting. Always follow the "Dose per Acre" for accurate results.

When to Use

Stunner is most effective when used as a preventative (prophylactic) treatment. Apply it when weather conditions favor disease development—such as cloudy, humid, or rainy weather—or at the very first sign of disease. Do not wait for severe infection to set in, as Stunner is designed as a preventative and early-intervention tool rather than a cure for heavy, established infections.

For grapes, the key target areas are Western Maharashtra districts including Nashik, Baramati, Sangli, Narayangaon, Solapur, and Satara, where Downy Mildew is a major challenge. For potatoes and tomatoes, apply when conditions are favorable for Late Blight—typically during cool, wet periods. Stunner is also an excellent choice during the monsoon season due to its rapid rainfastness of 1 to 4 hours.

Step by Step Usage Instructions

1. Prepare the spray solution: Measure the required dose of Stunner (80 ml per acre for all target crops). Mix the measured quantity in the recommended amount of water (200-400 L per acre depending on crop and canopy density).
2. Mix properly: Fill the spray tank with half the required water, add the measured Stunner, and stir well. Then add the remaining water and mix thoroughly to ensure a uniform suspension.
3. Apply as foliar spray: Spray evenly on the foliage, ensuring thorough coverage of the entire canopy. For grapes, target the bunch zone specifically. For potatoes, ensure the lower leaves are well covered to prevent tuber infection.
4. Timing of application: Apply preventatively when weather conditions favor disease, or at the very first sign of infection. Do not wait for severe disease symptoms.
5. Wear protective gear: Always wear gloves, mask, and goggles during mixing and spraying. Wash hands thoroughly after use.
6. Post-application: Stunner becomes rainfast within 1 to 4 hours. If rain occurs after this period, no re-spraying is needed.

Compatibility

Stunner mixes well with most insecticides and fungicides. It is often mixed with contact fungicides like Mancozeb or Chlorothalonil for broader disease protection. However, avoid mixing with highly alkaline substances like Bordeaux Mixture, as this can reduce the efficacy of Stunner. Always perform a jar test before mixing with new products to check compatibility.

Precautions & Safety

• Personal Protective Equipment (PPE): Always wear gloves, mask, and goggles when handling and applying Stunner
• Avoid contact: Avoid contact with skin and eyes. If contact occurs, flush with plenty of water for 15 minutes and seek medical attention
• Wash after use: Wash hands and exposed skin thoroughly with soap and water after handling the product
• Do not apply to stressed crops: Do not apply to crops under stress from drought, flooding, or other factors
• Environmental safety: Do not apply to water bodies or areas where there is a risk of runoff to water bodies. Stunner is harmful to fish and aquatic organisms
• Storage: Store in a cool, dry place away from food, feed, and drinking water. Keep out of reach of children
• Follow label instructions: Always read and follow the instructions on the official product label

Side Effects & Phytotoxicity

Stunner is a moderately toxic fungicide (Blue Triangle label). It is harmful to fish and aquatic organisms, so care must be taken to avoid spray drift or runoff into water bodies. Do not apply to crops under stress from drought, flooding, or other adverse conditions, as this may increase the risk of phytotoxicity. Stunner is non-toxic to honeybees, making it safe for use during pollination periods.

PHI / REI & Storage

Crop	PHI (Pre-Harvest Interval)
Grape	Use before fruit pruning / Check export limits (approx. 30-40 days before harvest for EU export)
Potato	7 Days
Tomato	3 - 7 Days

Storage: Store in a cool, dry place away from direct sunlight, food, and animal feed. Keep the container tightly closed when not in use. Store out of reach of children and unauthorized persons.