Leptomelanconium needle blight of pine
- French disease name: Brûlure des aiguilles à Leptomelanconium pinicola
- Pathogen name: Leptomelanconium pinicola (Berk. & Curtis) R.S. Hunt
- Class: Coelomycetes
Distribution
Western North America
Needle casts and blights of pines are common throughout British Columbia (B.C.) and the Yukon. The more common are native throughout the Pacific NorthwestDamage, symptoms and biology
Damage caused by foliage diseases has not been investigated in detail in the Pacific Region. It is likely that increment loss is substantial when climatic conditions make it possible for these fungi to become epidemic (11, 12). If climatic conditions favourable to these diseases persist, some young trees are reduced to a single annual increment of foliage and are sometimes killed as a result. Conditions optimal for fungus sporulation and infection are quite critical, and high humidity is the major requirement.Epidemics can be widespread and severe following a year in which the spring was wet. Because of the critical requirements for maximum spore production, dissemination and infection, plus the fact that needles are only susceptible to infection by needle casts from bud break until maturity, serious outbreaks over large areas occur only sporadically.
Exceptions occur: in the Kootenays there seem to be more years with epidemics than without. Epidemics of needle blights last 1 to 3 years, and then they collapse for unknown causes. Only small and weak native trees succumb during the epidemic.
Scirrhia pini, a native pathogen, produces a toxin (1) which our native pines seem to tolerate better than exotic species. Young native shore pine growing in small pockets are severely defoliated and some trees are killed in coastal areas. This pathogen has the potential to cause severe damage because of its ability to attack needles of all ages. Likewise, Leptomelanconium pinicola also is a severe defoliator and young trees may be killed of attacked for several consecutive years (10). L. pinicola is similar to S. pini, but lacks red bands on brown or straw-coloured needles.
Other information
Needle blights attack and fruit on any age of foliage and therefore are active not only in the spring, but any time there is a coincidence of high relative humidity and spores. Spores of needle blights are usually wind-borne for greater distances than spores of needle casts; therefore, needle blights are usually more serious than needle casts. Needle-blighted foliage is also cast from the tree after the spores are released.Canadian Forest Service Publications
Leptomelanconium needle blight of pine
Information on host(s)
In B.C., the distribution of some needle casts coincides with host distribution. Leptomelanconium pinicola has caused epidemics on ponderosa pine in the East Kootenay and on lodgepole pine in the Prince Rupert area.