Dutch elm disease is caused by:

Correct option is C

Dutch elm disease (DED) is a devastating vascular wilt disease of elm trees, caused by a fungal pathogen belonging to the genus Ophiostoma , most notably:
· Ophiostoma ulmi – identified as the original causal agent.
· Ophiostoma novo-ulmi – a more aggressive species responsible for later, more destructive epidemics.
�� Why the Correct Answer is (c) Fungus:
· Pathogen Type:
· The fungus invades the xylem (water-conducting tissues) of elm trees, blocking water transport, which leads to wilting, yellowing, and eventual death of the tree.
· Transmission:
· Spread primarily by elm bark beetles ( Scolytus species), which carry fungal spores from infected to healthy trees.
· Also spreads through root grafts between adjacent trees.
· Geographical Impact:
· First observed in the Netherlands in the 1920s, hence the name “Dutch” elm disease.
· The disease has decimated elm populations in Europe and North America.
· Symptoms:
· Wilting and yellowing of leaves starting from the top.
· Brown streaking in the sapwood.
· Progressive branch dieback, leading to total collapse.