Phytoplasma diseases of ornamental plants: An Indian overview

Abstract

The economic importance of ornamentals has been progressing significantly in many countries with international demand expanding continuously. Cut flowers represent the largest segment of the industry followed by flowering potted plants, trees, shrubs, annuals, flower bulbs and other propagation materials. Like other crops, ornamental plants are also affected by a number of pathogens such as fungi, bacteria, viruses, phytoplasmas etc. Among them, the phytoplasmas are equally important group of pathogens which drastically damage growth and marketing parameters of ornamental plants and thereby affecting their commercial value. Phytoplasmas cause diseases in several commercial cut flowers and ornamental plants causing serious economic losses all over the world. Phytoplasma diseases are a major constraint in commercial production of ornamental plants by lowering the quantum and quality gaining international importance. So far more than 26 ornamental plant species have been reported to be associated with phytoplasma infection from all over India belonging to six different phytoplasma groups, viz. aster yellows (16SrI), peanut witches ’broom (16SrII), clover proliferation(16SrVI), pigeon pea witches ’broom(16SrIX), rice yellow dwarf(16SrXI) and bermuda grass white leaf (16SrXIV) phytoplasma. Limited studies are made towards epidemiological aspects of these diseases in India. Major management practices adapted for phytoplasma disease management are using tetracycline treatment, insecticides for vector control and micropropagation for emission and elimination of phytoplasmas. In this review, an update status of progress on research work done on phytoplasma diseases of ornamentals in India is discussed.