Needle cast (Lophodermium seditiosum)
Damage, symptoms and biology
Infection occurs in late summer on the current year’s needles. The infection does not become apparent until the following spring when small brown spots develop on the needles. During the spring, the spots enlarge and the infected needles begin to turn yellow, then die and turn brown by early summer. The dead needles may stay attached to the twig or fall to the ground. These symptoms generally lead to detection of the disease. Infection causes the premature loss of needles, hence the term “needle cast”, and in severe cases, the death of seedlings and saplings may occur.
Loss of foliage causes reductions in growth and vigour, which lead to stunted seedlings and saplings. In larger trees the infection level is generally more severe on the lower branches, but the fungus can infect foliage throughout the entire crown. Entire seedling nursery beds may be killed.
Small, black, elongated fruiting bodies develop on the dead needles in late summer. In moist weather, these fruiting bodies erupt through the epidermis of the needle, split down the middle, and release spores. The spores are dispersed by the wind and rain and re-infect the current year’s needles. Lophodermium seditiosum overwinters on infected needles or on the ground.
Spraying nursery beds or high value plantations with a registered fungicide is an effective form of control. The spray must be applied before and during the peak sporulation period in the late summer, at a rate of one spraying every 2 to 4 weeks. The application of fungicides must be done by qualified, trained professionals. Irrigation of problem areas in nurseries should be done in the morning. Sanitization through removal of plants displaying symptoms of the disease is also recommended. Infected seedlings should never be outplanted because of the possibility of introducing the fungus into new areas.
In Christmas tree plantations, diseased or dead material should be removed and destroyed. Moreover, preventive measures such as controlling weeds between rows to ensure rapid drying of Christmas trees, hygiene around the perimeter of the plantation to reduce inoculum, and inspection of new plants all help to prevent new infections.
The same treatment recommendations apply to ornamental trees.
There may be confusion with Lophodermium pinastri. This related fungus is a litter decomposer that attacks weakened neddles or those that are already dead. It is characterized by the presence of black transverse bands on the needles. This fungus is not a pathogen. Hunt (1995) provides the most comprehensive review of needle-attacking fungi.
Canadian Forest Service Publications
Information on host(s)
Austrian pine, red pine, scots pine
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