Diplodia tip blight: what the agencies record

This page reports what the official source says. It is not legal advice: ask the office named here. It does not identify what is wrong with any tree and does not say what should be done about one. None of the four pages read lists Diplodia tip blight as regulated or notifiable. Each section names its source, all read on October 9, 2026. The full list of diseases is on the tree diseases page.

Names and cause

Natural Resources Canada, called NRCan, gives the fungus as Diplodia sapinea and the disease as Diplodia blight, formerly Sphaeropsis tip blight, a disease of conifers that does most damage to two- and three-needle pines. The University of Maine lists the other names as Sphaeropsis sapinea and Diplodia pinea. The South Dakota bulletin, revised June 2021, uses the older name Sphaeropsis sapinea. West Virginia University Extension says the disease was formerly known as Sphaeropsis.

Hosts

Source	Hosts it records
NRCan	In Canada, lodgepole and ponderosa pine in the west and jack and red pine in the center and east; non-native Scots and Austrian pine in Ontario, with Austrian pine the most susceptible and Scots pine a close second. Also recorded on balsam fir, white spruce, black spruce, eastern white pine, tamarack, Douglas-fir, Norway spruce, Colorado spruce, mugho pine and European larch
South Dakota	Over 20 pine species, including Austrian, Scots and ponderosa pine; ponderosa pine stands in the Black Hills and windbreak and ornamental pines across the state are affected
University of Maine	All pines, with Austrian pine severely affected, and white, Norway and blue spruce; damage to native trees is not commonly seen
West Virginia University	Austrian and Scotch pine are named as very susceptible

NRCan and Maine agree that trees planted outside their natural range are the ones most often infected. NRCan says the fungus has also been isolated in Europe from stressed broadleaf trees in the birch and beech families.

Where it is recorded

NRCan says the fungus is endemic to North America and widespread in Canada wherever its hosts grow, with most reports from Ontario and others from British Columbia, Manitoba, Quebec, Nova Scotia, and Newfoundland and Labrador. It says the fungus is also found across Asia, Europe and northwestern Africa and wherever hosts have been introduced in South Africa, Oceania and South America, and is likely to have reached many regions on planting stock and seeds. South Dakota says the disease spread from Europe to all parts of the world and has global distribution. The two sources disagree on origin: NRCan calls the fungus endemic to North America, and South Dakota says it came from Europe.

Signs the sources list

NRCan lists shoot dieback, dead needles, resinous cankers on stems and branches, sapwood stain, crown dieback, blighted cones and seed contamination. It describes dead shoots with stunted straw-colored needles stuck in place by pitch, mainly in the lower third of the crown on mature trees. South Dakota gives the most obvious symptom as stunted brown needles on dead tips in May and June. West Virginia University describes brown, dead shoot tips that seem to appear overnight, with dead patches scattered through the tree and dark brown or black wood. All four sources give the black fruiting bodies, called pycnidia, as the telling sign. NRCan, South Dakota and Maine place them under the needle sheaths, and NRCan, South Dakota and West Virginia University also find them on cones. Maine says the lower branches tend to be the most severely infected.

Timing and how it spreads

NRCan says new pycnidia mature in late spring or early summer and overwinter on dead needles, cones and the bark of living trees, and that spores are released during rainy periods, spread by rain, wind, insects or pruning tools and enter through wounds, buds, young cones, new needles and tender shoots. South Dakota says spores are dispersed from March through October, mostly in rainy periods, that current-year shoots are susceptible from bud break in April through mid-June, and that second-year seed cones are susceptible when they elongate, around late May in that state. It says incidence of shoot infection is greater on older trees, which carry more seed cones. Maine says as little as 12 hours of wetness is enough for infection and that the fungus overwinters in diseased needles, cankers and especially two-year-old cones. West Virginia University says it overwinters on cones from the previous growing season, on the bark and on the tips of previously infected shoots.

Stress and harm to the tree

NRCan says the fungus is usually present at low levels in healthy stands and can live as an endophyte, but can cause severe damage and death in trees stressed by drought, hail damage or other pests. South Dakota also calls it an endophyte in healthy pines, so that almost all trees are infected but show no symptoms until stressed. Maine says it mostly attacks mature trees stressed by drought, root restriction or planting-site problems. NRCan says repeated infections over consecutive years can eventually lead to death, and that infections on tolerant trees mostly stay in the current year's growth and in second-year cones.

Regulated status and reporting

None of the four pages names a regulation, quarantine order or report line for Diplodia tip blight. For the agencies that take reports of regulated pests, see the guides on reporting a pest in Canada and the United States.

Management as the sources list it

NRCan, Maine and West Virginia University Extension describe sanitation, NRCan and Maine describe keeping trees healthy, and all four mention a fungicide. South Dakota says pruning is of limited value for controlling the disease. This page gives no product names, rates or timings. For who may apply pesticides, see pesticide licences.