Sycamore Problems

Sycamores head the menu for several pests and fungus…

Frequent rains and cool temperatures form favorable conditions for blight.

The most serious disease of sycamore trees is leaf blight, also known as anthracnose and scorch. The destructiveness of this disease, which can be severe in some parts of the state every year, is often under-estimated. Although a single attack is seldom harmful, repeated attacks can weaken trees and make them susceptible to winter injury and damage by borers.

Leaf blight symptoms…

The first symptom of leaf blight is the sudden browning and death of single leaves or clusters of leaves as they're expanding in the spring. This is often confused with frost injury. Later, brown, dead areas appear along and between the veins of other leaves. Trees may be defoliated and remain bare until late summer when new leaves are formed. Leaf blight may attack and kill small twigs, too. Cankers appear on the leaf spurs and on twigs, they look like sunken areas with slightly raised margins. Trees moderately infected with leaf blight will have scattered clusters of dead leaves which contrast sharply with unaffected foliage.

Fungus blight…

A fungus with several distinctly different types of spores causes blight. The fungus may live through the winter in the vegetative stage in fallen infected leaves and in twig cankers. In the South, it spends the winter in the spore stage on dormant buds. The first infections of the young leaves in spring may originate from spores that lived through the winter on leaves on the ground or from spores developed on infected twigs, from spores on the dormant buds. The prevalence and severity of attacks are determined by weather conditions. Frequent rains and cool temperatures favor rapid spread. The severity of the shoot blight stage depend largely on the average temperature during the two weeks after leaves first emerge.

To control diseases of sycamores…

Gather and burn all the fallen leaves in the autumn. This destroys the organism that lives through the winter and produces spores for the next spring's infections. Whenever it's feasible, prune infected spurs and dead twigs and burn them. Some control can be provided by spraying zineb or cooper fungicides. Apply the first spray just before the leaves unfurl. The second when leaves are half-grown and the third when the leave are fully grown. If trees suffer from repeated attacks, fertilize them heavily in the fall or the next spring to increase their vigor.

Insect problems…

The giant bark aphid, the sycamore plant bug, sycamore tussock moth and scales rely on sycamores for sustenance.

• The giant bark aphid often attacks the twigs of sycamore trees and may gather in clusters on the undersides of the limbs. They exude great quantities of honeydew, a sweet fluid which often turns blackish. To control aphids, spray them with Malathion .
• Sycamore plant bugs suck out the plant juices on the upper sides of sycamore leaves, leaving a poisonous material which results in yellow or red spots. As the leaves grow, the injured areas drop out, leaving holes. To control the sycamore plant bug, spray trees with Malathion in early April and again two weeks later.
• Several species of scale insects occasionally infest sycamores. To control them, spray your trees with Malathion or Orthene in late spring when the young scales are crawling. A dormant oil spray should be applied in early spring if infestations are usually heavy.

For more information on sycamore problems; contact your local County Extension Office.