Pine needle cast

Pathogen and disease type
The disease is caused by the ascomycete fungus Lophodermium pini-excelsae, which belongs to the needle cast disease group. This parasitic fungus colonizes the needles of pine trees, interrupting vital physiological functions and leading to premature shedding of the foliage. It is considered a significant threat to pine health, particularly in young ecosystems.

Affected crops
The primary host for this pathogen is the Scots pine (Pinus sylvestris). It is particularly destructive in nursery settings, young plantations, and forests where natural regeneration occurs. In such environments, the fungus can spread rapidly among closely packed trees, leading to severe defoliation and growth retardation in juvenile pine stands.

Symptoms and signs of infection
Infected needles initially turn yellow and eventually transition to a reddish-brown or dark brown color. A diagnostic feature is the presence of black, transverse lines or small, oval-shaped fruit bodies (apothecia) on the surface of the affected needles. Eventually, the infected needles fall off, resulting in the characteristic thinning of the pine canopy, usually starting from the bottom of the tree.

Development and spread conditions
The development of the fungus is favored by cool, humid weather conditions. High atmospheric humidity and frequent rain events facilitate the dispersal of spores via wind or water splashes. Infection typically begins in late summer and autumn when spores land on healthy needles and germinate under favorable moisture conditions, overwintering within the host tissues.

Harmfulness and protection measures
The harmful impact manifests as reduced growth, loss of aesthetic value, and potential mortality of young saplings in epidemic years. Effective control strategies include:

• maintaining proper stand spacing to improve airflow;
• removing and destroying infected debris;
• monitoring for early signs of yellowing;
• applying systemic or contact fungicides during the sporulation season to protect foliage.