Pests of Specific Crops

Pest Description
Leaf Spot (Cercospora sp. and other fungi): Discrete
leaf spots, generally smaller than anthracnose
lesions and not on margins of leaves. Severe
infections may cause premature leaf fall.
Rust (Puccinia sparganoides): This fungus forms aecia
on leaves of ash in Central and Eastern North
America only. Not known to occur in BC.
Insects:
Ash and Lilac Borer (Podosesia syringae): It was first
reported in BC in 2006, but is well established
in the US. The adult is a clearwing moth that is
similar in appearance to a paper wasp. It
usually has a single generation per year. The
female moth deposits her eggs in bark crevices
within 10 to 14 days of emergence. Upon
hatching, the larvae tunnel into the trunk and
feed beneath the bark. The larvae do excavate
galleries in the wood. The mature, 3 cm larvae
overwinter inside the tree. Adult moths emerge
the following spring. Infestations lead to
unsightly scars and swollen areas on the trunk
and, can weaken branches. Severe infestations
can kill a tree. Hosts include European ash,
privet, lilac and mountain ash.
Fall Webworm (Hyphantria cunea): Branches may be
defoliated by hairy caterpillars with black
heads and pale yellow bodies with dark stripes
along back. Webs are usually on tips of
branches in late summer and fall. Moths are
pale and 1.2 cm long.
GLEDITSIA - HONEY LOCUST
Insects:
Honey Locust Plant Bug (Blepharidopterus chlorionis):
The pest was detected in Oregon in 2008. It has
one generation per year. Eggs hatch in early
spring and the nymphs feed on new growth,
causing stippling and leaf distortion. Adults
also feed on leaves that can lead to defoliation.
Honey Locust Pod Gall Midge (Dasineura gleditchiae):
Pupae overwinter in the soil and adults emerge
in the spring when new growth begins. The
adult is a small fly (3 mm long). Eggs are laid
in expanding leaflets and hatch in a few days.
Larval feeding cause leaves to become globular
or pod-like. The pods contain one or more
whitish larvae. After 3-4 weeks of feeding, the
larva pupates and an adult fly emerges. Galled
leaflets may drop prematurely. Continued
galling and defoliation may cause the death of
small branches, but new growth often develops
at the base of dead twigs. There may be three
or more generations per year.
Chemical Control
(rate per 100 L water; or per
unit area if indicated)
DACONIL 2787F: 250 mL
DACONIL Ultrex: 150 g
Apply at spring bud break and
repeat every 7-14 days as necessary.
NOVA 40W: 25-34 g
Apply every 10-14 days.
See General Insect and Mite
Management: Bark Beetles and
Woods Borers, Chapter 11.
Pesticide sprays should be
applied before eggs hatch. Use
pheromone traps (isomate-P) to
monitor for moth emergence.
Spray 10 to 14 days following
emergence.
AMBUSH 500EC: 7 mL
DIPEL WP: 62.5 g
DIPEL 2X DF: 31 g
ORTHENE 75% SP: Mist blower
= 1,312 g/1,000 L; Hydraulic
sprayer = 637 g/1,000 L
POUNCE 384 EC: 9 mL
SEVIN T&O: 230-350 mL
HORTICULTURAL OIL (97%): 1 L
Use to control the eggs. Since the
eggs hatch within a couple of
days, application timing is
critical. Monitor expanding
leaflets for red eggs in the spring
(late March to early April) and
spray when eggs are found.
Cultural Management
Rake up and burn, bury or
compost fallen leaves.
Fungicide treatment is rarely
necessary.
Water and mulch trees to
reduce stress. Do not wound
the trunk or main branches.
Remove webs as soon as seen
in mid-summer.
See General Insect and Mite
Management: Caterpillars and
Moths, Chapter 11.
Nursery Production Guide Pests of Specific Crops • 15