Figure 10. - Dead pines with only red crowns.
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.
[ top ]
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
Figure 11. - Brown patches signaling recent fire.
[ top ]
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.
[ top ]
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
[ top ]
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.