Metalaxyl-M

Metalaxyl-M is a highly effective systemic fungicide belonging to the phenylamide chemical class (acylalanines). It is characterized by rapid absorption through roots, stems, and leaves, providing both curative and preventive control.

The mode of action involves inhibiting the ribosomal RNA synthesis of the pathogen. By targeting RNA polymerase, the substance disrupts the protein synthesis process, effectively halting mycelial growth and spore development.

As the R-enantiomer of metalaxyl, Metalaxyl-M offers higher biological activity, allowing for lower application rates compared to the racemic mixture. This significantly reduces the environmental load per hectare.

Its systemic nature ensures that the active ingredient is translocated acropetally (upwards) within the plant vascular system, protecting newly developed foliage that was not present at the time of application.

The substance exhibits excellent rainfastness, as it is rapidly absorbed into the plant tissue shortly after application, making it reliable even in regions with frequent rainfall.

This active ingredient is specifically designed to target Oomycetes, a group of fungus-like pathogens. It is instrumental in managing diseases that thrive under high humidity and cool conditions.

It provides control against major diseases including Phytophthora species (late blight of potatoes and tomatoes), Peronospora species (downy mildew on onions, brassicas, and sunflower), and Plasmopara viticola (grapevine downy mildew).

Metalaxyl-M is widely used as a seed treatment to provide protection against soil-borne Oomycetes such as Pythium, which cause damping-off and seedling blight during the germination stage.

The fungicide is effective at various stages of plant growth, offering a crucial barrier against primary and secondary infections throughout the season.

• Late blight in Solanaceae.
• Downy mildew in vegetables.
• Downy mildew in sunflower.
• Damping-off in seedlings.
• Root and stem rots caused by Pythium.

Application rates for Metalaxyl-M depend on the crop type, disease pressure, and the method of delivery. It is frequently formulated in combination with contact fungicides to broaden the spectrum of activity.

Optimal results are achieved through preventive applications before visible symptoms occur or at the earliest onset of disease signs, ensuring the systemic barrier is active within the plant tissue.

The duration of protection typically ranges from 10 to 14 days, though this can vary based on environmental conditions and the rate of plant growth, which may dilute the internal concentration of the fungicide.

In seed treatment programs, precise dosage is required to provide long-lasting control during the critical first stages of plant development without causing phytotoxic stress to the embryo.

When preparing spray solutions, ensuring good coverage is vital, as the systemic movement depends on the effective uptake of the product through all exposed green surfaces of the plant.

The primary concern with the extensive use of Metalaxyl-M is the development of resistance in target pathogen populations. The phenylamide group is known for a high risk of resistance selection.

To mitigate this risk, it is strictly recommended to implement resistance management strategies, such as alternating Metalaxyl-M with fungicides of different modes of action and limiting the total number of applications per season.

Users must follow personal protective equipment (PPE) requirements during handling and application to prevent dermal or respiratory exposure to the active ingredient.

Proper storage in original, sealed containers is essential to prevent degradation. Dispose of containers and rinsate in accordance with local environmental regulations to protect groundwater and aquatic life.

Adherence to pre-harvest intervals (PHI) is mandatory to ensure that residue levels in the harvested produce comply with safety standards and regulatory requirements.