What Is Tridemorph and Why Is It an Important Fungicide in Cereals and Oilseeds?

Technical Introduction

Tridemorph is a systemic fungicide belonging to the morpholine chemical group. It was one of the first ergosterol biosynthesis inhibitors (EBIs) developed for agriculture.

Unlike triazoles (which inhibit sterol demethylation), Tridemorph blocks Δ⁸→Δ⁷ isomerase and Δ¹⁴-reductase enzymes in fungal sterol biosynthesis. This prevents the formation of ergosterol, an essential component of fungal cell membranes, leading to disrupted membrane function and fungal death.

Its selectivity and systemic action make it effective against major fungal pathogens in cereals and oilseed crops.

Applications

• Cereal Crops (Wheat, Barley, Rye):

  • Controls powdery mildew (Erysiphe graminis).

  • Active against leaf spots and rusts when combined with other fungicides.

• Oilseed Rape (Canola):

  • Used against powdery mildew and other leaf diseases.

• Bananas:

  • Historically used for Sigatoka leaf spot (Mycosphaerella musicola), though less common today.

• Sugar Beet:

  • Provides control against powdery mildew (Erysiphe betae).

• Other Crops (Limited Registration):

  • Sometimes used on coffee, groundnuts, and vegetables in certain countries.

Advantages

• Systemic Protection: Absorbed and translocated in plant tissues, protecting new leaves.

• Unique MOA Within EBIs: Inhibits different sterol enzymes than triazoles, useful in resistance management.

• Effective Against Powdery Mildew: Historically one of the most reliable morpholines for cereals.

• Tank-Mix Compatibility: Often combined with triazoles (e.g., propiconazole, cyproconazole) or strobilurins for broader disease control.

• Resistance Management Tool: Provides diversity in fungicide programs by targeting sterol isomerases instead of demethylases.

Specifications (Typical Parameters)

FAQ

Q1: What is Tridemorph mainly used for?
A: It is used primarily to control powdery mildew in cereals, oilseed rape, and sugar beet.

Q2: Is Tridemorph systemic?
A: Yes, it is systemic and translocated within plant tissues, giving protection to new growth.

Q3: How does Tridemorph differ from triazole fungicides?
A: Triazoles inhibit CYP51 demethylation, while Tridemorph inhibits sterol isomerase and reductase enzymes. This difference makes it a valuable resistance management tool.

Q4: Does Tridemorph control rusts and leaf spots?
A: It has limited activity on rusts and leaf spots, so it is usually applied in mixtures with triazoles or strobilurins for broader coverage.

Q5: Is resistance to Tridemorph a concern?
A: Yes, resistance in powdery mildew populations has been observed. To delay resistance, it should be used in tank mixes or rotation programs with other fungicide classes.