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.