Heterosporium allii

Onion leaf showing signs of leaf blotch. Image: Clarissa Balbalian, Mississippi State University, Bugwood.org

  • Leaf blotch affects onions, shallots, chives, garlic and leeks.
  • Damages leaves.
  • Leaf infection results in long wounds that develop parallel to leaf veins. At first, wounds appear as yellow areas but later turn brown. Weak, old leaves are more likely to be colonised by this fungus than healthy leaves. An abundance of brown to olive-brown spores are produced giving affected tissues a dark, velvety appearance. As the disease progresses onion plants begin to die.
  • Spread by infected debris, soil and seed.

High priority pest of: Onions

Scientific name: Cladosporium allii syn. Heterosporium allii
EPPRD Category:
Life Form: Fungus

Pest Documents

FS: fact sheet

CP: contingency plan

DP: diagnostic protocol