Ivy, English (Hedera)
Plant Health Problems
Diseases caused by Fungi:
Powdery mildew, Erysiphe.
White powdery spots or patches develop on leaves and occasionally on stems.
Symptoms often first appear on the upper surfaces of the leaves and are usually
most pronounced during hot weather. Heavily infected leaves turn brown and
shrivel.
Disease can be minimized by avoiding overcrowded spacing of plants and by
carefully picking off affected leaves as soon as symptoms are evident.
Symptomatic leaves can be placed into a plastic bag in order to avoid spreading
the spores of the fungus to other plants. Use of fungicides is usually not
necessary. However, applications can be made as soon as symptoms are visible.
Among the compounds registered for use in Connecticut are horticultural oil,
sulfur, potassium bicarbonate, and thiophanate-methyl. Consult the label for
dosage rates and safety precautions.
Leaf spots, Phyllosticta, Glomerella.
Large circular to irregular tan spots develop on leaves, often showing
concentric rings of fruiting bodies of the fungus. Affected twigs may also be
killed back.
Efforts to maximize plant vigor by fertilizing and watering are helpful.
However, watering should be done early in the day to give the foliage a chance
to dry before nighttime. It is also helpful to pick and remove symptomatic
leaves as soon as they develop. Although not usually necessary, applications of
fungicides can be made when new growth emerges in the spring. Among the
compounds registered for use in Connecticut are ferbam, mancozeb, and copper
compounds. Consult the label for dosage rates and safety precautions.
Diseases caused by Bacteria:
Bacterial leaf spot, Xanthomonas.
Symptoms first appear as pale green, irregular water-soaked spots with yellow
or sometimes translucent borders. Spots eventually turn brown to black and are
often first evident on lower or inside leaves of densely crowded plantings.
Infections on the petioles produce black lesions which crack longitudinally and
cause entire leaves to wilt and die. Stem infections may result in yellowing,
reduced growth, and dead patches.
This disease can be minimized by improving air circulation by thinning the
plants and by avoiding overhead irrigation. Picking and destroying infected
leaves is also helpful. Chemical control can supplement other methods for
disease management. Among the compounds registered for use in Connecticut are
elemental copper, copper hydroxide, and copper sulphate pentahydrate. Consult
the label for dosage rates and safety precautions.
Diseases caused by Physiological/Environmental Factors:
Winter injury.
Symptoms of injury appear as tan to brown papery blotches on the leaves.
These are usually found at the leaf margins but they can appear anywhere on the
leaf. In extreme cases, entire plants may be affected and dead patches
subsequently develop in a planting bed. Injury is associated with many factors
including extremely cold temperatures, temperature fluctuations and freeze-thaw
cycles, and drying winds. English ivy often shows injury from low temperature.
Baltic variety is less susceptible and is suggested for use in exposed locations.
This type of injury can be minimized by maintaining plant vigor by proper
fertilizing and watering during periods of drought.
Insect Problems:
Black vine weevil, Otiorhynchus sulcatus.
The larvae of this weevil often injure English ivy in nurseries and ornamental
plantings by feeding on the roots. The tops of injured plants first turn
yellow, then brown, and the severely injured plants die. Leaf notching by
adults can be unsightly. The 1/2" long adult weevil is black, with a
beaded appearance to the thorax and scattered spots of yellow hairs on the wing
covers. Only females are known. Adults are flightless and feed nocturnally. The
legless grub is white with a brown head and is curved like grubs of other
weevils. Adults and large larvae overwinter, emerging from May - July. The
adults have to feed for 3-4 weeks before being able to lay eggs. Treating the
soil with insect pathogenic nematodes may control the larvae and should be the
first line of defense for landscape plantings. Acephate and fluvalinate are
among the compounds registered for control of this pest in Connecticut, and may
be applied when there is adult feeding and before egg laying starts. The usual
timing for these foliar sprays is during May, June and July at three week
intervals. Insecticide resistance is very common; be aware that adults may
appear to be dead following contact with fluvalinate, but may recover from
poisoning within a few days. Consult the labels for dosage rates and safety
precautions.
Ivy aphid, Aphis hederae.
These are soft bodied, pear-shaped insects, from 1/12" to 1/4" (2-6
mm) long, whose identifying characteristic is the presence of cornicles, that
look like tailpipes, on the top rear of the body. Antennae are usually shorter
than or equal to the body in length. They have piercing-sucking mouthparts and
excrete honeydew, which supports black sooty mold. Aphids may be managed by
spraying with insecticidal soap or ultrafine horticultural oil, which are among
the compounds registered for control of this pest in Connecticut. Aphids on ivy
outdoors can be controlled using malathion sprays or imidacloprid can be
applied as a soil drench for season-long, systemic control. Consult the labels
for dosage rates and safety precautions.
Imported longhorned weevil, Calomycterus setarius.
The grayish adults are about 1/8" long. They emerge from late June through
July and early August. Eggs are laid in the soil, and larvae are present from
midsummer until June of the following year. They feed on the small roots of
host plants but more often on those of legumes or on organic matter. Both wild
and cultivated plants are attacked. Usually, the adults feed on the upper
surface at the edge of the leaves and on flowers in sunlight or shade. Host
plants include annuals, perennials, shrubs, deciduous trees, and evergreens.
Larvae may be controlled by drenching insect pathogenic nematodes around the
roots.
Mealybugs, Planococcus citri.
Mealybugs often infest English ivy in houses and greenhouses. White cottony
masses appear on leaf surfaces, in leaf axils and sheaths. These insects damage
plants by sucking plant sap. Among the compounds registered for control of this
pest in Connecticut are insecticidal soap, ultrafine horticultural oil or
resmethrin. These products are most effective against crawlers. Because of
overlapping life stages in a home environment, multiple applications will be
needed to control this pest. Spray needs to contact the insect. Imidacloprid,
applied as a soil drench, will provide season-long systemic control. Consult
the labels for dosage rates and safety precautions.
Mites.
Houseplants such as gardenia, English ivy and the rubber plant are sometimes
attacked by mites such as the twospotted spider mite. Mites are microscopic,
have eight legs and spin webs. Most of them like hot, dry conditions and will
multiply rapidly when these conditions are present. They feed on the undersides
of leaves with their piercing-sucking mouthparts. Symptoms of mite feeding are
a yellow stippling of leaves and, when the infestation is severe, webbing may
encase the plant. At this point, it's very difficult to penetrate through the
webbing with miticides to obtain direct contact.
Control should begin with keeping the air in the home or greenhouse somewhat humid. Insecticidal soap and ultrafine horticultural oil, which are among the compounds registered for use against this pest in Connecticut, will control mites. Multiple applications may be needed. Hexythiazox or abamectin (a restricted use product) are also effective against this pest. Consult the labels for dosage rates and safety precautions.
Soft brown scale.
This scale insect infests English ivy and many other kinds of plants. The
soft scale, Coccus hesperidum, is very thin, oval, and semi-transparent.
One remedy is to spray with insecticidal soap or malathion, which are among the
compounds registered for control of this pest in Connecticut. These control
sprays may need to be repeated if only the crawler stage is controlled.
Imidacloprid, applied as a soil drench, will provide season-long systemic
control. Consult the label for dosage rates and safety precautions.
White or oleander scale, Aspidotus nerii.
This circular scale infests the leaves and stems of various greenhouse plants
including English ivy. This scale is pale yellow, about 1/10" in diameter
and circular in form. Insecticidal soap or disulfoton systemic granules, which
are among the compounds registered for control of this pest in Connecticut, can
be used, if infestation is severe. In a home or greenhouse situation, all life
stages may be present at one time. Insecticidal soap may only kill crawlers,
and since there is no residual activity, repeated applications may be required
to break the life cycle. Consult the labels for dosage rates and safety
precautions.