Distinguishing SPB Spots
from Other Tree Problems

Groups of dead pines with only red crowns are commonly seen during SPB surveys (fig. 10). They may indicate SPB spots that are inactive or no longer expanding. But the red crowns may have been caused by lightning, fire, herbicides, or bark beetles other than the SPB. With close observation, you can learn to recognize damage by these other causes and avoid reporting it as SPB damage.

Fire

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Trees killed by recent fires appear as red or brown patches, with crowns all the same color (fig. 11). Light fires sometimes scorch trees without killing them, which leaves the lower crown red and the upper crown green. Scorched earth beneath trees and fire-control lines also signal recent fire occurrence.

Figure 11. - Brown patches signaling recent fire.

Foliage Diseases

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Pines suffering from diseases, especially pine " needle cast," may show symptoms similar to those of SPB-killed trees. Pond pine along the Atlantic Coastal Plain is frequently infected with needle-cast fungi, as are loblolly and slash pines. Common from February through June and again in September and October, needle cast primarily hinders spring and early fall aerial surveys. Moderately affected trees have greener upper crowns than lower crowns. When the spring growth flush begins, green terminal shoots appear on trees with needle cast; no green shoots come out on SPB-killed trees once they turn red.

Herbicides

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Uniform strips of yellow- or red-crowned trees along powerlines, pipelines, roads, and railroad tracks (fig. 12) are most often an indication of herbicide application and not of SPB infestations. Sprays applied to agricultural crops often drift onto adjacent stands of trees, causing foliage discoloration. When herbicide damage occurs in mixed pine-hardwood stands, hardwoods are affected along with pines. In timber stand improvement operations, only hardwoods are affected.

Figure 12.-Herbicide-damaged trees along highway right-of-way (North Carolina Forest Service).

Other Bark Beetles

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Single, widely scattered yellow- or red-crowned trees observed during summer surveys generally indicate lightning strikes or attacks by bark beetles other than SPB. Black turpentine beetles typically kill single pines. Most Ips infestations are small and scattered, often containing only red-topped pines (fig. 13), unlike varicolored SPB spots. Ips attacks occur primarily during extended droughts or adjacent to recently logged areas or in storm-damaged stands. In case of large infestations, ground checking is the only way to determine whether Ips or SPB is responsible.

Figure 13- Scattered pines infested by Ips beetles.