Question

For the effective control of early blight of potato, which fungicide is most suitable?

• A. Zineb
• B. Dithane M-45
• C. Blitox-50
• D. Difolatan

Hint:

Potato Blight $\rightarrow$ Dithane M-45.
Mancozeb is the "Universal" protectant fungicide.
Remember Alternaria (Early) vs Phytophthora (Late) blights; Mancozeb helps with both!

Answer 1

The Correct Option is B

Step 1: Understanding the Question:
The question asks to identify the most commonly recommended and effective fungicide for managing "Early Blight" in potato crops.

Step 2: Detailed Explanation:

• About Early Blight:
Early blight is caused by the fungus Alternaria solani.
It is characterized by dark, concentric "target-board" spots on the leaves. If left uncontrolled, it can significantly reduce potato yields.

• Dithane M-45 (Mancozeb):
Mancozeb (the active ingredient in Dithane M-45) is a coordination product of zinc ion and manganese ethylene bisdithiocarbamate.
It is a broad-spectrum, "protectant" fungicide. It provides a multi-site mode of action, making it very difficult for fungi to develop resistance.
It is the standard recommendation for controlling both Early Blight and Late Blight in potatoes globally.

• Evaluating Other Options:
Zineb: An older dithiocarbamate fungicide. While effective, Mancozeb is generally preferred for its better tenacity and spectrum.
Blitox-50 (Copper Oxychloride): A copper-based fungicide. It is effective but can sometimes cause phytotoxicity in certain potato varieties if not applied correctly.
Difolatan: An older fungicide with good properties but less commonly used or available than Mancozeb for routine blight management.

• Application:
Farmers typically apply Dithane M-45 as a preventative foliar spray at intervals of $10$-$14$ days, especially during humid or rainy weather when fungal pressure is high.

Step 3: Final Answer:
Dithane M-45 (Mancozeb) is the most suitable and widely used fungicide for early blight of potato.