Plant Health Problems
Growth and flowering of lavender is favored by planting in a bright, sunny location with well-drained, moderately fertile soil. Lavender does not thrive in shady, damp locations, with excessively wet soil. High levels of organic matter in soil, which increases water-holding capacity, also are not favorable to the growth and establishment of lavender. Careful selection of a planting site will increase the chances of successfully growing lavender. Once established, however, lavender is generally disease-free.
Orange tortrix caterpillar, Argyrotaenia citrana.
This and other caterpillars of moths chew the foliage of lavender. The orange tortrix feeds on new foliage, webbing it together. At maturity, the caterpillar is about 1/2" long. Pupation occurs in this nest. Adult moths lay eggs in clusters on leaf surfaces or the smooth stems of new growth. There may be two generations a year. When needed, young caterpillars can be controlled using Bacillus thuringiensis var. kurstaki or acephate, which are among the compounds registered for use against this pest in Connecticut. Consult the labels for dosage rates and safety precautions.
Fourlined plant bug, Poecilocapsus lineatus.
This bug lays eggs in the soft stems. They hatch about the middle of May and the young bugs suck the sap from the tender leaves. They molt five times and when mature, about the middle of June, they have wings and are nearly 1/3" long. The insect body is yellow, marked lengthwise on the wings with four black stripes alternating with three green stripes. The injury to the leaves consists of sunken areas around the punctures. These areas later appear as circular transparent spots and finally as circular holes. This insect injures the new leaves of many different kinds of annual and perennial plants and shrubs. There is one generation each year. The nymphs can be managed by spraying with azadirachtin, ultrafine horticultural oil, insecticidal soap or malathion, which are among the compounds registered for control of this pest in Connecticut. Consult the labels for dosage rates and safety precautions.