Missouri Landscape & Nursery Association/MLNA
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St. Charles, MO 63304
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Diplodia tip blight

Diplodia pinea is known to occur in 30 Eastern and Central States and in Hawaii and California. The fungus infects more than 20 pine species. It is commonly found on Austrian pine, which, since the early 1900's, has been widely used in the Central and Eastern United States in landscape, windbreak, and park plantings.

Diplodia pinea is known to occur in 30 Eastern and Central States and in Hawaii and California. The fungus infects more than 20 pine species. It is commonly found on Austrian pine, which, since the early 1900's, has been widely used in the Centra

Damage by D. pinea is frequently reported on Scots (P. sylvestris L.), red (P. resinosa Ait.), ponderosa (P. ponderosa Laws.), and Mugo (P. mugo Turra) pines in the United States. D. pinea infects Monterey pine (P.radiata D. Don) in California and has seriously damaged extensive plantings of this species in the Southern Hemisphere (New Zealand, Australia, South Africa).

The most conspicuous symptom of diplodia blight is brown, stunted new shoots with short, brown needles. Needles on infected new shoots often become discolored (tan, brown) while still encased in fascicle sheaths. Presence of resin droplets and one or a few very short needles are usually the first indications that a new shoot is infected. Entire new shoots are killed rapidly by the fungus. Trees repeatedly infected have some branches killed back to the main stem. Repeated infections reduce growth, deform trees, and ultimately kill them.

New shoots throughout the crown may be infected, although damage is generally first evident in the lower crown. Usually infection varies considerably among major branches. Occasionally, after 2 or 3 successive years of infection, tree tops are extensively damaged. Although pines of all ages are susceptible to D. pinea, damage is more severe in older plantings.

Although unwounded new shoots can be infected, D. pinea can infect both current-year and older tissues through wounds. In the Southern Hemisphere, D. pinea has often severely damaged trees wounded by hail. Also, damage by D. pinea has been associated with wounds made by insects. Tissues wounded during pruning or shearing operations may become infected. Wounded tissues remain vulnerable to D. pinea infection for several days. Stems of Austrian, Scots, and ponderosa pines wounded in May and late June were vulnerable to infection for at least 12 days after wounding.

Control: Use native pines in plantings, such as eastern white pine and decrease drought stress by correct site placement and adequate water management. Diplodia tip blight may respond to fungicide treatments however precisely timing is required to coincide with swelling and opening of the buds. When candles begin expanding it is too late!

Tip blight on scotch pine

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