Clematis vines, flowers and plants - dealing with diseases, insects and pests
Dealing with diseases affecting Clematis vines, plants and flowers
Clematis is attacked by several fungal diseases like leaf spot and stem rot (Ascochyta clematidina) commonly called wilt, powdery mildew (Erysiphe polygoni), smut (Urocystis carcinodes), leaf blight (Phleospora adjusta) and crown gall by the bacterium (Agrobacterium tumefaciens).
In leaf spot and stem rot, fungus attacks the stems and leaf near the soil. Small water soaked spots which become yellow –coloured with reddish margins develops on the leaves. The fungus penetrates into the stems and causes the upperparts to die. Infection may occur from spores produced on the old stems. It can be controlled by picking and destroying disease infected leaves and stems. Regular spray with Bavistin (0.02%) or dithiocarbamate fungicide at fortnight intervals early in the growing season can be effective. Other leaf spot diseases are caused by Cylindrosporium clematidis, Cercospora rubigo, C.squalidula, Glomerella cingulata, Phyllosticta clematidis, Pamularia clematidis and Septoria clematidis.
Powdery mildew disease occurs during rainy season when humidity is high. It attacks on flowers and young stems. It can disfigure leaves and flower buds causing infected flower bud’s failure to open. Plant should be treated with fungicide like Karathan (0.03%) when first symptoms are noticed.
Insects and other pests affecting Clematis
Although insects are not a common problem, but aphids (found on new growth), Black blister beetle (Epicanta Pennsylvania), Clematis borer (Alcathoe caudata), Japanese weevil (Pseudocneorhinus bifasciatus) and several mites can also infest this host. In outdoors, slugs and snails may feed on newly planted vines.
Black blister beetle may devour flowers and foliage or bore into unopened flower buds. It can be controlled by spray of Sevin or Malathion. Clematis borer is 2/3 inch long, dull white larva feeding on fleshy roots and crown of vines. Infested vines become stunted and less vigorous. Dig out the larvae and spray the Methoxychlor several times at two weeks interval around the base of the plant and soil.