A. It sounds like euonymus scale. Euonymus fortunei and its cultivars, such as 'Emerald 'n Gold,' are very susceptible to this insect pest. Euonymous scale frequently goes unnoticed until the damage is severe and dieback is apparent. Adult euonymous scale insects appear as tiny white (male) or brown (female) immobile bumps on stems and the undersides of leaves. If left unchecked, the plants can die after several years of infestation.
Adult euonymous scale insects have a waxy covering that makes them impervious to insecticide applications. They overwinter as fertilized females that begin laying eggs under the protection of their waxy covers in early spring. The eggs hatch from late May through June.
Immature scale insects are known as crawlers because it is the only point in their life cycle when they are mobile. Crawlers are also the most susceptible to insecticide applications. Once they settle in a spot and insert their mouthparts into the stem or leaf, they secrete their protective covering and spend the rest of their lives there. A second generation is produced from late July through August.
To control euonymus scale, start by pruning and destroying heavily infested stems. Monitor the plants for crawler activity from mid-May through June and again from mid-July through August. Crawlers are small, but visible to the naked eye. You may want to use a magnifying glass or hand lens to see them more clearly. They are yellowish-orange in color, and move about on the foliage and stems. Once you notice their activity, begin making insecticide applications. Orthene (acephate), Sevin (carbaryl), Bayer PowerForce Multi-Insect Killer (cyfluthrin), horticultural oil, BioNeem (neem), insecticidal soap, and malathion are labeled to control euonymous scale. Repeat applications may be necessary.
Q. I am growing several types of tomatoes in my garden. I have noticed that the leaves are tightly curled on some of them, while other plants look normal. Is this a problem?
A. Leaf roll on tomatoes is a physiological symptom specific to certain cultivars of tomatoes. Those that contain a specific gene -- the wilty gene -- will develop the characteristic lengthwise curling of the leaves in response to high temperatures, drought and prolonged periods of wet soil. The symptoms often appear when the plants are carrying a heavy load of fruit. It is common for the lowest, oldest leaves on susceptible plants to show rolling more than newer leaves.
First Published: August 28, 2004, 4:00 a.m.
