The recent discovery of orange discoloration on young lodgepole pine trees on the Bridger-Teton National Forest near Alpine, WY has been attributed to a tree fungus known as “Lophodermella Needlecast”.
Starting in late May, along the upper Greys River between Forest Park and Corral Creek, needles that were produced last year on young lodgepole pine began discoloring, with most largely turning orange in color. Most of these needles have now been cast, or fallen off, and these young trees are currently growing green needles on the tips of the branches to sustain the growth and survival of the young trees. A fungus, Lophodermella concolor, is responsible for infecting and killing the needles on these young trees. Many of the young lodgepole pine had also lost the previous year’s needles to a prior infection, but tree mortality is not anticipated, nor is the infestation anticipated to become widespread. Other infestations may have occurred on other parts of the Bridger-Teton National Forest, but they have not been confirmed.
Research has indicated that outbreaks of Lophodermella Needlecast are likely facilitated by moist conditions during the time of the maturing of the fruiting body and spore release by the fungus. A loss of growth in the young trees will occur, but mortality of young trees is very infrequent. “The infestations will diminish with drier seasonal climatic conditions that are more closely representative of area averages,” said Timber Program Manager Roger Powell. “This needle rust and cast disease in the lodgepole pine is currently quite widespread along the upper Greys River on the Bridger-Teton National Forest,” he said. “Talking with a valley resident, I understand that the needle discoloration only started happening 3 to 4 weeks ago, with the needles from last year’s growth now being cast,” said Powell.
This may not be the first time this fungus has affected the young trees in the Greys River area. “It appears that many of the trees lost the needle growth from 2-years ago as well,” Powell said. “This year’s developing needles currently appear unaffected,” he said.