Onion with Yellow Leaves: Causes & Solutions
Allium cepa
Onion is a plant that needs and frequent watering. When showing yellow leaves, it may indicate issues related to its environment or care.
Is your Onion showing yellow leaves? Discover 6 possible causes and how to treat them.
🔍 Possible Causes (6)
Thrips
Thrips are tiny cigar-shaped insects (1/25-inch long) that damage plants by sucking plant juices and scraping at fruits, flowers, and leaves. With over 6,000 species and rapid reproduction (lifecycle as short as 14 days), they can quickly infest plants and transmit viruses like tomato spotted wilt virus.
✓ Related symptoms:
- • Yellowing and eventual death of affected leaves
⚡ Quick Fixes:
Step 1
Downy Mildew
Downy mildew is a fungal-like disease caused by oomycetes (water molds) that thrives in cool, wet conditions. It affects a wide range of plants, causing yellowing leaves with fuzzy white-gray growth underneath, leading to defoliation and reduced yields if left untreated.
✓ Related symptoms:
- • Small green or yellow translucent spots on leaves
- • Yellow to brown irregular patches on upper leaf surfaces
- • Leaf yellowing, curling, and distortion
⚡ Quick Fixes:
Remove and destroy all infected plant parts. For severe infections, remove entire plant.
White Mold
White mold (Sclerotinia sclerotiorum) is a devastating fungal disease affecting over 400 plant species worldwide. The fungus produces black, seed-like structures (sclerotia) that can survive in soil for 5 or more years. The disease is favored by cool, moist weather (50-68°F/10-20°C), especially during flowering.
✓ Related symptoms:
- • Sudden wilting and yellowing of leaves
⚡ Quick Fixes:
Immediate removal
Fusarium Wilt
Fusarium wilt is a serious fungal disease caused by the soil-borne fungus Fusarium oxysporum. The fungus invades roots and blocks the water-conducting vessels (xylem) of the plant, causing progressive wilting and eventual death. Host-specific forms of the pathogen exist that attack different plant species.
✓ Related symptoms:
- • Asymmetrical yellowing of leaves (one side of plant or leaflets)
- • Pale green to golden yellow foliage
⚡ Quick Fixes:
Remove Plant
Anthracnose
Anthracnose is a fungal disease caused by fungi in the genus Colletotrichum that affects many plants, including vegetables, fruits, and trees. The disease thrives in cool, wet conditions, causing dark, sunken lesions on leaves, stems, flowers, and fruits.
✓ Related symptoms:
- • Small irregular yellow or brown spots on leaves
⚡ Quick Fixes:
Remove and discard all visibly infected parts
Root Rot
Root rot is a serious fungal disease that affects the root system of plants, causing them to decay and die. It is primarily caused by overwatering, poor drainage, or soil-borne fungi such as Pythium, Phytophthora, Rhizoctonia, and Fusarium. The disease thrives in waterlogged conditions where roots are deprived of oxygen, making them susceptible to fungal infection.
✓ Related symptoms:
- • Yellowing or browning of leaves
⚡ Quick Fixes:
Emergency unpotting