What Is Cyazofamid and Why Is It a Key Fungicide for Oomycete Control?

Technical Introduction

Cyazofamid is a systemic fungicide belonging to the imidazolinone chemical class, developed specifically for controlling diseases caused by oomycete fungi (water molds), such as Phytophthora and Plasmopara species.

Its mode of action is highly unique: Cyazofamid inhibits cytochrome bc1 complex (complex III) at the Qi site in fungal mitochondria. This disruption prevents ATP synthesis, leading to energy depletion and fungal cell death. Because of its target-specific activity, it is classified by FRAC as Group 21 (QiI inhibitors).

Cyazofamid is absorbed into leaf tissues and provides translaminar activity, protecting both upper and lower leaf surfaces. It works best as a protective fungicide, stopping spore germination and mycelial growth.

Applications

• Potatoes & Tomatoes: Highly effective against late blight (Phytophthora infestans).

• Grapes: Controls downy mildew (Plasmopara viticola).

• Cucurbits (Cucumber, Melon, Pumpkin, Zucchini): Prevents downy mildew infections.

• Leafy Vegetables (Lettuce, Spinach, Cabbage): Effective against downy mildew.

• Tobacco: Used to control blue mold (Peronospora tabacina).

• Ornamentals & Specialty Crops: Protects against oomycete-induced diseases.

Advantages

• Oomycete-Specific: Highly effective against Phytophthora and Plasmopara, which cause severe crop losses.

• Translaminar Protection: Moves into the leaf tissue, protecting both sides of the leaf.

• Preventive & Early Protective: Stops infection before symptoms appear.

• Unique Mode of Action: Effective against resistant strains where other fungicides fail.

• Rainfastness: Strong adhesion to leaf surfaces, maintaining protection after rainfall.

• Tank-Mix Flexibility: Often combined with multi-site fungicides (e.g., mancozeb, chlorothalonil) to strengthen disease control and resistance management.

Specifications (Typical Parameters)

FAQ

Q1: What diseases does Cyazofamid control best?
A: It is highly effective against late blight in potatoes/tomatoes and downy mildew in grapes, cucurbits, and leafy vegetables.

Q2: Is Cyazofamid systemic or contact?
A: Cyazofamid is locally systemic (translaminar), meaning it moves into the treated leaf tissue but does not move extensively through the entire plant.

Q3: Can Cyazofamid cure existing infections?
A: No, it is primarily a preventive fungicide. It must be applied before or at the very early stage of infection.

Q4: How can resistance be managed with Cyazofamid?
A: Since it has a single-site mode of action, it should be rotated or tank-mixed with multi-site fungicides like mancozeb or copper oxychloride.

Q5: Is Cyazofamid rainfast?
A: Yes, it has strong adherence to leaf surfaces, providing reliable protection even after rainfall.