Brown Spot Needle

Brown Spot Needle

Brown spot needle disease, caused by the fungus Scirrhia acicola, is considered the most serious disease of longleaf pine. It causes seedlings to remain in the grass stage (an early growth stage of longleaf in which the seedling looks like a clump of grass) for an abnormally long time, delaying initiation of height growth and causing loss of potential wood production. Severely infected trees often die. Young longleaf trees become more resistant to this disease once they grow out of the grass stage.

This disease occurs from Virginia to Texas, primarily on the Atlantic and Gulf Coastal Plains. It is more severe in certain geographic areas (see map below). It has been estimated to reduce total annual growth of southern pine timber by 16 million cubic feet (0.453 million cubic meters).

At present, longleaf pine occupies only about 5 million acres of its former 60 million acre range. Difficulties in storing and handling longleaf pine seedlings have discouraged managers from planting this species.

Brown Spot Disease Range

Recent work has led to the production of healthier seedlings for planting; planting success has improved on sites where, historically, longleaf was the dominant species (Cordell and others 1989, Kais 1989).

Several possible treatments are available for managers to limit the impact of this disease on their grass-stage longleaf pine seedlings. They include silvicultural, fire, and fungicidal options.

Chemical treatment of seedlings and prescribed burning are most likely to be used by managers of private industry land and managed public land. State forestry agencies are having success assisting private nonindustrial landowners in controlling brown spot, but there are a huge number of landowners to contact and this effort is very slow.

It is expected that disease incidence will increase as attempts are made to return longleaf to its native range.