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Plant Pathology Infobytes

March 10, 1999

Pine Needle Rust - Not as Bad as it Looks

The needles on young pine trees in the home landscape and in plantation plantings often develop small, orange colored growths during late winter and early spring. These structures are highly visible, and their sudden appearance may lead homeowners to the conclusion that something seriously wrong is about to happen to their trees.

These growths are actually a stage in the life cycle of the fungus which causes a disease plant pathologists refer to as Coleosporium needle rust. The outgrowths from the needles resemble small "wings" or "sacks" and although they may become quite numerous, trees infected by this fungus disease suffer very little damage. Thus, homeowners shouldn't be concerned about needle rust causing tree death.

Pine needle rust shows up on all species of southern pines - loblolly, slash, longleaf, and shortleaf - as well as introduced pine species which are sometimes grown in Christmas tree plantings or urban landscapes. Since needle rust doesn't cause any real damage to any of these trees, it's not necessary to apply fungicides, or carry out any other control procedures, in an attempt to "make this stuff go away."

As a point of interest, the fungus which causes needle rust is related to another common rust - fusiform rust, which also infects southern pines. Fusiform rust is a more serious disease and frequently causes tree mortality. This rust will make its appearance in a few more weeks when enlarged , cankered areas on the trunks and branches of loblolly and slash pines take on a orange appearance, as their surfaces become covered with a spore stage of this rust disease.

Questions about the quality care of your trees and other landscape plants? Give us a call, or drop by the county Extension office for more information.

Infobytes newsletter was written by the late Dr. Frank Killebrew, Extension Specialist.