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 is mancozeb. Consult the label for dosage rates and safety precautions. Foliar nematodes, Aphelenchoides spp. These plant-parasitic worms attack virtually all plant parts and may cause leaf lesions, yellowing, necrosis and leaf drop, and bud malformation.
Plants often appear dwarfed and leaves at the growing tip are distorted.
Stems of infected plants may appear swollen and the internodes are shortened. Since these nematodes live and move in water films, this disease can be minimized by reducing leaf moisture by avoiding overhead irrigation and by providing adequate spacing of the plants to maximize drying of the foliage. It is also helpful to remove infected tissues, debris, or plants. Insect Problems Aphids. The violet aphid, Micromyzus violae , and probably also the green peach aphid, Myzus persicae , occasionally infest violet.