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Monadnock Ledger-Transcript
Tuesday, July 19, 2016

Drought stressors have worsened a fungal threat that has been affecting the area’s white pine trees.

If a white pine has brown needles or is shedding needles at a large rate, a fungi known as needlecast may be the cause, according to Jeremy Delisle, program coordinator at the Education Center of the University of New Hampshire Cooperative Extension.

“A stressed plant is more susceptible to fungal and insect attacks,” Delisle said in an interview.

“Basically, what we’re seeing today is a result of fungal infections that likely got started in the spring of 2015 and are coming to fruition now.”

In 2015, said Delisle, the conditions in spring were moist enough that the fungi was able to become established and infect the needles. When the summer dried up, the fungi generally went dormant.

The dry summer last year and the lack of heavy snowfall during the winter months to replenish groundwater supplies meant that trees came out of the winter already stressed by drought. 

That, paired with at least three other identified fungal infections impacting local trees, could be concerning if the fungus is able to gain a strong foothold. Conifers shed their needles every two years, and are able to survive on one year’s growth of needles, so it is not immediately an issue, said Delisle, but it could become one in the future.

“It’s a long game with trees,” said Delisle.

It’s rare that fungal infections of this type kill a tree, said Delisle, although added stressors like drought can lead to tree mortality. He recommended that if homeowners have a pine that they believe is infected, they should consult a certified arborist. Ensuring the tree has sufficient irrigation and pruning surrounding foliage to give the pine adequate sunlight, particularly on its lower branches, will likely allow the tree to gain enough health to survive the fungal infection, said Delisle.

“These fungi like wet, shady environments and by opening up that canopy, we reduce that. Those branches and needles dry faster and give less time for that pathogen to cause damage,” he said.

Trees can be treated with fungicide in the early spring before the infection gets a strong foothold. 

For now, Delisle advises, homeowners should keep an eye on their trees and take notes of any appearing to drop needles. The issue may resolve itself as weather patterns return to a more normal rainfall and the trees are able to recover from drought conditions.