Worldwide important phytoplasmal diseases of woody plants.

摘要

Phytoplasma 'Candidatus Phytoplasma' is the trivial name for fastidious biotrophic bacteria of the class Mollicutes. These pathogens cause devastating diseases in crops worldwide. Infected herbaceous plants tend to show specific symptoms of virescence and phyllody. Diseased woody plants suffer mostly from abnormal growth, and leaf and fruit deformations. Infected plants can die back. Phytoplasmas colonize the phloem sieve tubes in their host plant. They are transmitted by vectors, grafting, parasitic plants and root grafts. Similar to viral diseases, control measures against phytoplasmas aim to prevent infection (through the use of healthy planting materials and robust cultivars, for example) or inhibit the spread of the pathogen (such as through quarantine, eradication of infected plants and vector control). This paper focuses mainly on the worldwide importance of the following diseases caused by phytoplasmas: apple proliferation, pear decline, Bois noir, apricot chlorotic leaf roll, elm yellows, Flavescence doree, Hydrangea phyllody and lethal yellowing. Information on causal agents, distribution, transmission and control is provided for each disease.