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Hemlock Diseases: Cankers, Needle Blights, and Rusts

Disease Reference Table

Disease	Symptoms	Pathogen/Cause	Management
Cytospora Canker	Slightly sunken cankers girdle and kill branches.	Valsa (Cytospora)	Prune infected branches.
Fabrella Needle Blight	Needles in lower tree turn brown and fall in late summer, leaving bare twigs. Fruiting structures: small dots on needle underside, white then dark, lining each side of main vein.	Fabrella tsugae	No control recommended. Little damage unless tree under other stresses (drought, insect attack).
Cone and Twig Rust	Cones covered with dusty yellowish spores. Twigs twist, die, have yellowish spores.	Melampsora farlowii	No control recommended. Fungus only requires hemlock to complete life cycle.
Needle Rust	Current-season growth slightly swollen and curled. Orange-yellow spores coat infected tissue; infected parts die in summer. Spores develop on poplar leaves where fungus overwinters.	Melampsora abietis-canadensis (hemlock ↔ poplar) Pucciniastrum hydrangeae (hemlock ↔ hydrangea) Pucciniastrum vaccinii (hemlock ↔ rhododendron and others)	No control recommended. Fungi overwinter on broadleaf hosts, then spread to hemlock.

Fabrella needle blight (Penn State Dept. of Plant Pathology collection) from PA Dept. of Natural Resources. Prepared by Gary W. Moorman, Professor of Plant Pathology.

Plant Disease: Sunflower Diseases: 9 Common Ones; Pruning Hemlock Trees for Hedge Shape and Size; Topped Hemlock Recovery: What to Expect After Improper Pruning; Plant Diseases 101: What to Do When Your Plant Looks Sick; Plant Virus Diseases: Symptoms, Transmission, and Control Strategies; Palm Disease Guide: Nutritional, Environmental, and Fungal Disorders; Pansy Disease Management: Anthracnose, Leaf Spots, and Root Rot Control; Cotoneaster Disease Management: Botryosphaeria Canker and Fire Blight Control; Elm Tree Diseases: Symptoms, Causes, and Management Strategies; Hemlock Diseases: Cankers, Needle Blights, and Rusts

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