NC Cooperative Extension   Service

Master Gardener Decision Support Guide

Woody Ornamentals

Rhododendron


Short cuts for Rhododendron Answers

The following problems are listed for this plant and considered when developing the diagnostic key. If the caller provides accurate answers to the questions, the ones that are linked should key out to that specific problem. The unlinked problems are expected to key to the point where the caller is asked to submit a sample. These samples will often require diagnostic procedures such as soil testing, pathogen culture, Elisa or other test beyond the resources of the average Master Gardener Volunteer or County Extension Agent.

Insects:
Otiorhynchus sulcatus (black vine weevil)
Rhadopterus picipes (cranberry rootworm)
Choristoneura rosaceana (obliquebanded leafroller)
Lithophane antennata (green fruitworm)
Oligonychus ilicis (southern red mite)
Oberea myops (azalea stem borer, rhododendron stem borer)
O.tripunctat (dogwood twig borer)
Vespa crabro germana (European hornet)
Dialeurodes chittendeni (rhododendron whitefly)
Dysmicoccus wistariae (taxus mealybug)
Graphocephala coccinea (redbanded leafhopper)
G.fennahi (rhododendron leafhopper)
? (lacebugs)
Pseudococcus longispinus (longtailed mealybug)
? (rhododendron gall midge)

Scales:
Eriococcus azaleae (azalea bark scale)
Pulvinaria ericicola (cottony azalea scale)
P.floccifera (cottony camellia scale)

Disease:
Agrobacterium tumefaciens (Crown Gall)
Alternaria (leafspot)
Botryosphaeria dothidea (dieback)
B.obtusa (dieback)
Botrytis blight (dieback, gray mold)
Cercospora handelii (leafspot)
Exobasidium (Leaf Gall)
Meloidogyne (Nematode)
Ovulinia azaleae (petal blight)
Phomopsis (dieback)
P.rhododendri (dieback)
Phytophthora (dieback)
P.cinnamomi (dieback)
Pucciniastrum vaccinii (rust)
Sclerotium rolfsii (dieback)
? (powdery mildew)
lichens

Enviromental:
Cold Temperature Leaf roll

Other Pests:
flying squirrels suspected

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Designed by David Goforth on December 30, 1997.
Contents modified on February 18, 1998.
Contents checked on February 18, 1998.