Pests of Specific Crops

Pest Description
HEDERA - ENGLISH IVY
Chemical Control
(rate per 100 L water; or per
unit area if indicated)
Diseases:
Bacterial Leaf Spot (Xanthomonas hortorum pv.
hederae): Leaf spots are usually angular with
reddish margins and exhibit dark
discolouration running into the veins. Petioles
and stems may become black and shriveled.
Grey Mould (Botrytis cinerea): See General Disease Management: Powdery Mildew, Chapter 9.
Leaf and Stem Spots/Anthracnose (Phyllosticta /
Colletotrichum spp.): Circular leaf spots, often
with concentric rings and small, black fungal
fruiting bodies. Entire leaves can wilt if lesions
girdle stems.
HYDRANGEA
Diseases:
Grey Mould (Botrytis cinerea): This common fungus
causes browning of petals and a grey, fuzzy
mould on flower clusters during wet weather.
Leaf Spots (Cercospora and Septoria spp.): Small to
large leaf spots containing tiny, black fungal
bodies (pycnidia). Severe infections may cause
leaf drop.
DITHANE DG, M-45 or WSP
80WP: 125-250 g
PENNCOZEB 80WP: 125-250 g
Use low rate when treating soft,
new growth or when repeated
applications are planned.
BOTRAN 75W: 175 g
ROVRAL 50WP-WDG: 100 g
DACONIL 2787F: 250 mL
DACONIL Ultrex: 150 g
Apply before blooming, since
may discolour blooms.
Cultural Management
Avoid overhead watering.
Pick off affected leaves when
first spots appear.
Avoid overhead watering.
Remove infected plant parts if
practical. Fungicides are
rarely necessary in the
landscape.
Remove blooms after
flowering. Infected flowers
falling on leaves can lead to
leaf and stem infections.
Reduce humidity and improve
air circulation.
Pick off leaves as spots
appear. Collect and destroy
fallen leaves. Fungicides are
rarely needed for control.
Powdery Mildew (Erysiphe polygoni): Lower leaf surfaces become covered with a powdery, white growth; upper surfaces
may be purple-brown. Blooms may be stunted & malformed. See General Disease Management: Powdery Mildew,
Chapter 9.
Sunscald: When bright sunny weather follows a
prolonged dull period in late spring or early
summer, large areas of leaves and shoots may
wilt, develop a water-soaked appearance and
finally turn grey to brown.
ILEX - HOLLY
Diseases:
Green Algae: Green to black coloured algae coating
on leaves, twigs, branches and trunk.
Leaf and Twig Blight (Phytophthora ilicis): Black
blotches and rot of leaves and petioles,
followed by leaf drop, starts on lower branches
in late fall and progresses upward during cold,
rainy weather in winter. Symptoms are usually
observed in January. Twig cankers and berry
rot may also occur.
DITHANE DG, M-45 or WSP
80WP: 180-250 g
MANZATE DF & PRO-STICK:
180-250 g
PENNCOZEB 80WP: 180-250 g
Apply at any time during the
growing season. Do not apply
close to harvest as visible residue
may make holly unmarketable.
DITHANE DG, M-45 or WSP
80WP: 180-250 g
PENNCOZEB 80WP: 180-250 g
Apply in the fall before the onset
of fall rains. Avoid application
close to harvest to avoid visible
residue.
Provide temporary shade or
misting during sudden hot
spells that usually occur in
June.
Prune to increase air
circulation.
Prune out diseased
branches and remove
fallen leaves and plant
debris, where practical.
16 • Pests of Specific Crops Nursery Production Guide