Elytroderma Needle Cast - Field Guide to Diseases and Insect Pests of Idaho and Montana Forests

Elytroderma Needle Cast

Elytroderma deformans (Weir) Darker

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

Host. – Ponderosa pine.

Distribution. – Range of host in Idaho and Montana.

Damage. – Witches brooms form in branches, and small trees are often deformed by loose brooming of the leader. Needles are infected yearly within the broom and are cast after 1 year. Growth loss, deformation, and occasionally death of small trees result.

Identification. – New infections are started by spores in late summer. Needles are infected and the fungus grows into the twig and branch cambium. The witches broom, which forms after a few years' infection, combined with discoloration and shedding of needles within the broom, are good indications of this disease (fig. 81). Infection within the broom is chronic; the new needles are reinfected every year and are shed the following summer. Branch infections are detected by cutting away the bark to expose the cambium. Small pockets of dark resin are distributed throughout the phloem adjacent to the cambium. Fruiting bodies are black lines parallel to the needle axis at the lower end of needles (fig. 82). The fruiting bodies split the epidermis in mid to late summer to release spores.	Image Unavailable
	Figure 81 - Elytroderma Needle Cast causes witches brooms to form in systemically infected braches.
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	Figure 82 - Fruiting bodies of Elytroderma Derformans are black lines near the base of discolored needles.

Similar damages. – Ponderosa pine dwarf mistletoe causes witches brooms which retain the normal complement of needles. The needles are green in dwarf mistletoe-infected brooms. Dwarf mistletoe plants are generally present as well. Other needle casts of ponderosa pine will cause discoloration but not brooming.

Link to Table 5. – Comparison of Common Pine Needle Casts.

Link to Images in Forestry Images

References.

Anonymous. 1982. For. Insect & disease identification and management. USDA For. Serv.,Northern Region; Idaho Dept. of Lands, Insect and Disease Control; Montana Dept. of State Lands, Division of Forestry. 192 p.

Bega, R. V. 1978. Diseases of Pacific Coast conifers. USDA For. Serv. Ag. Hndbk. No. 521, 206 p.

Hepting, G. E. 1971. Diseases of forest and shade trees of the United States. USDA For. Serv. Ag. Hndbk. No. 386, 658 p.

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