Updates on phytoplasma diseases management

Phytoplasmas are cell wall-less, phloem-limited, and insect vectors transmitted prokaryotes responsible for economically significant diseases on many different crops in the world. Their unique nature requires focused management strategy based on polyphasic integrated approach. Legislative measures are important for preventing the entry, spread, and establishment of exotic phytoplasmas into new areas. Using certified pathogen-free nursery materials is essential for exclusion of the phytoplasmas from production areas. A temporary remission of symptoms by injecting tetracycline antibiotics into the plant was demonstrated, but their use for chemical control is limited due to impractical application and environmental risks. In the field, phytoplasma diseases management is based mainly on the eradication of infected plants and insects' vector control. Pesticides are commonly used for insect vector control, but they seem to be less efficient than more reliable insect-proof screening or another physical prevention method. The use of resistance plants is considered as an effective and environmentally safe approach for preventing phytoplasma diseases. Over last decades, some phytoplasma-resistant or tolerant genotypes and progenies were identified. The high resistance was determined in some apomictic Malus sieboldii progenies to apple proliferation phytoplasma, also in the genotype “Xingguang” to jujube witches' broom phytoplasma. However, for many economically important phytoplasma diseases such as palm lethal yellowing disease, no resistant genotypes were identified. Another strategy for the control of phytoplasma diseases is inducing resistance in plants by activating plant defense system with abiotic or biotic inducers. Resistance inducers gave promising results against phytoplasma diseases such as grapevine yellows, witches' broom diseases of lime however, for their practical implementation, better understanding of host–pathogen interactions is necessary.