A major symptom of onion/twister is

A major symptom of onion/twister is

  1. appearance of dark brown spots on leaves ✓
  2. mottling of leaves
  3. rottening of roots
  4. rottening of buds

Explanation

A major symptom of onion/twister is the appearance of dark brown spots on leaves. Onion/twister is a disease that affects onion plants, causing the leaves to twist and curl.