Pests of Specific Crops

Pest Description
VIBURNUM
Diseases:
Powdery Mildew (Microsphaera spp.): Leaves become
covered with white, powdery growth in late
summer. The same fungus infects a wide range
of woody, deciduous hosts.
Insects:
Viburnum Leaf Beetle (Pyrrhalta viburni): The larvae
and adults both cause severe leaf
skeletonization and defoliation of ornamental
viburnums. Viburnum opulus is a preferred
host, but it also causes moderate to slight injury
on V. dentatum, V. lantana, V. tinus and V.
trilobum. The viburnum leaf beetle has one
generation per year. It overwinters as eggs,
which are usually deposited in a straight row
on the lower surface of 1- or 2-year-old twigs.
The eggs hatch in the spring and the larvae
begin to feed. In early summer, the larvae drop
to the ground to pupate. Adult beetles emerge
one month later. Female beetles will lay up to
500 eggs from late summer to the first frost.
Chemical Control
(rate per 100 L water; or per
unit area if indicated)
DACONIL 2787F: 250 mL
DACONIL Ultrex: 150 g
ACTARA 25 WG: 280 g/ha
CONSERVE 480 SC: 25
mL/ha
Cultural Management
Fungicide applications are
not usually warranted on
landscape plants. Sulphur
should not be used on
Viburnum. See General Disease
Management: Powdery Mildew,
Chapter 9.
To manage this pest prune
out and destroy infested
twigs after egg laying has
stopped in the fall.
See Appendix K for
information on the
susceptibility of Viburnum
species to the viburnum leaf
beetle.
44 • Pests of Specific Crops Nursery Production Guide