Mancozeb Fungicide Mode of Action

Mancozeb works by stopping fungi from growing on the plant.
It does this by blocking important processes the fungus needs to survive. When Mancozeb is sprayed on leaves or stems, it stays on the surface and kills fungal spores before they can infect the plant. That’s why it’s called a protective, contact fungicide—it prevents problems before they start.

1. Multi-Site Inhibition

Mancozeb is a multi-site fungicide, meaning it affects multiple enzymes and pathways in fungal cells at once. This broad action disrupts essential functions like:

• Respiration (energy production)

• Amino acid synthesis

• Lipid metabolism

Because it hits several targets, fungi struggle to develop resistance against it—making Mancozeb a long-lasting, reliable choice for growers.

2. Dithiocarbamate Chemistry

Mancozeb belongs to the dithiocarbamate class of fungicides. Its active molecules contain metal ions (zinc and manganese) that react with fungal enzymes containing thiol (-SH) groups. This interaction deactivates key proteins in the fungi, stopping cell function and spore germination.

3. Protective, Not Curative

Unlike systemic fungicides that move through the plant, Mancozeb is a contact fungicide. It does not enter the plant’s vascular system but remains on the surface to protect against new infections. This means:

• It should be applied before or at early disease stages

• It must be reapplied regularly, especially after rain

4. Prevents Spore Germination

One of Mancozeb’s most important roles is preventing fungal spores from growing. Once the fungicide coats the plant surface, spores that land cannot germinate due to disrupted oxidative enzyme activity—especially glutathione reductase and dehydrogenases.

5. Broad-Spectrum Disease Control

Thanks to its mode of action, Mancozeb is effective against a wide variety of fungal pathogens, such as:

• Phytophthora (blights)

• Alternaria (leaf spots)

• Peronospora (downy mildews)

• Septoria, Cercospora, and more

This wide range of activity is directly tied to how Mancozeb disrupts multiple processes in fungi.

6. Low Resistance Risk

Because Mancozeb targets many sites in the fungal metabolism, the risk of resistance development is extremely low. It’s often recommended in fungicide rotation programs and tank mixes to:

• Delay resistance to systemic fungicides

• Extend the effectiveness of disease control strategies

7. Environmental Surface Action

After application, Mancozeb forms a protective film on the plant surface. Its activity depends on:

• Good coverage during spraying

• Minimal wash-off, which is why repeat application is key in rainy or irrigated environments

Summary

Mancozeb’s mode of action is purely preventive, blocking fungal development before infection begins. It works on the plant surface, affects multiple fungal enzymes, and offers broad-spectrum protection with low resistance risk. Understanding this mechanism helps ensure effective use and integration into your crop protection strategy.