Delphinella Shoot Blight - Field Guide to Diseases and Insect Pests of Idaho and Montana Forests

Delphinella Shoot Blight

Delphinella abietis (Rostr.) E.Muller

From: Field Guide to Diseases and Insect Pests of Idaho and Montana Forests, USDA Forest Service Northern Region, Publication Number R1-89-54

Hosts. – Subalpine fir and grand fir.

Distribution. – Range of hosts; particularly common at high elevations and in frost pockets.

Damage. – shoots and leaves are killed in spring or early summer. Shoots and needles wilt and shrivel. Severe infection halts branch and terminal growth for season; chronic infections result in bushy trees because terminal buds are killed. Appearance of Delphinella damage is very similar to frost damage.

Identification. – Earliest signs of infection are slightly chlorotic needles on new shoots in spring. Needles may be girdled by cankers at their bases. As the fungus moves into shoots, shoots begin to wilt and shrivel. Infections occurring early in the season tend to kill all needles on a shoot and all or most of the shoot. Later-season infections may kill selected needles, only the tips of some needles, and only the tips of new shoots (fig. 115). Tiny, round, black fruiting bodies develop on the upper surfaces of needles and on dead shoots in midsummer. Dead needles and shoots are red or brown the first year after infection and gray or black the second year. Blighted shoots and needles remain attached for one to several years.

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Figure 115 - Needles and shoots are killed
by Delphinella Shoot Blight in early summer.

Similar damages. – Frost damage closely resembles Delphinella blight. Absence of frost damage on nearby trees of other species, and presence of fruiting bodies in midsummer are the best indicators of Delphinella shoot blight.

References.

Funk, A. 1985. Foliar fungi of western trees. Canadian Forestry Service, Pacific Forest Research Centre BC-X-265, 159 p.

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