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From the Pests of Ornamental Series
Diseases In some areas and during especially wet seasons, disease of English ivy (Hedera helix) may be quite destructive, causing early leaf fall and death of tender stems. Leaf Spot and Stem Spot Description: Oval or circular brown spots are present on both surfaces of the leaves. Small black bodies may be seen scattered over the surface of the spots. Infected stems are girdled, causing them to collapse and die.
Leaf Spot and Twig Blight Description: Light brown spots occur on the leaves. These spots may have a target- board effect. Infected plants appear ragged due to leaf fall and blight of the twigs.
Bacterial Leaf Spot Description: The disease is most prevalent in greenhouses. Pale green, water-soaked spots appear on the leaves. As the spots enlarge, they become brown or black with red margins. The leaf petioles become black and shrivel. The black decay may extend from the tips of young twigs into the old wood. Cankers may form on the stems, girdling them. A bacterial ooze may be seen on these cankers, when environmental conditions are warm and moist.
Scab Description: Raised, circular or "scabby," brown spots occur scattered over the leaf (occasionally on the veins). When these spots are numerous, they often ran together. Spots on the lower surface of the leaf may be slightly sunken in the center; on the upper leaf surface, the spots may have a purple border.
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