Phaeoacremonium (Phaeoacremonium decline)

Phaeoacremonium decline is a serious fungal disease characterized by the colonization of the xylem tissue of woody plants. The pathogens involved, primarily species of the genus Phaeoacremonium, are key components of the complex known as grapevine trunk diseases, often acting in synergy with other fungi like Phaeoacremonium aleophilum.

The primary host for this fungus is the grapevine (Vitis vinifera), but it has a broad host range, including various fruit trees and woody ornamental plants. In vineyards, the fungus leads to severe structural degradation of the cordons and trunk, which directly disrupts the transport of water and essential nutrients from the roots to the canopy.

Clinical symptoms are variable and often include stunted growth, chlorosis, and the characteristic leaf striping, sometimes referred to as tiger-stripe symptoms. Internal symptoms are diagnostic: when the trunk or cordons are sliced, one can observe brown or black streaking and wedge-shaped necrotic lesions in the woody tissue, which eventually become brittle and decayed.

Disease spread is primarily mediated by airborne conidia that settle on fresh pruning wounds. Rainfall and high humidity during the dormant season or early spring facilitate spore release and infection. Because the pathogen can remain dormant within the host for years without visible signs, it is often unknowingly spread through the propagation of infected nursery stocks.

Management of the disease relies heavily on cultural practices and integrated pest management (IPM). Chemical eradication after the fungus has established itself in the woody heartwood is largely ineffective. Growers must prioritize protecting pruning wounds with pruning sealants or biological control agents, ensuring nursery health, and rigorously sanitizing all cutting tools to prevent cross-contamination between vines during seasonal operations.