ARI REVIEW FOR 2016-2017

PLANT PROTECTION Research activities in Plant Protection concern the disciplines of Plant Pathology and Entomology. Under each of these disciplines, specialised studies are conducted to address major crop protection problems associated with particular pests (insects, mites) or diseases (viral, prokaryotic and fungal). In addition, joint multi- disciplinary research projects targeting all important pests and diseases of particular crops are undertaken. All studies are governed by the considerations of sustainability in crop protection and production, food quality and safety, environmental protection and the utilisation of new technologies for the development of more effective crop protection practices. Plant Pathology research includes the implementation of modern nucleic acid diagnostic assays for plant pathogens. Research effort has been focused on the development of new effective detection tools in order to identify the phytosanitary status of plants, for certification and quarantine purposes. In line with the above principles, one of the main activities of the Section concerns the development of integrated pest management (IPM) strategies, based on various combinations of ecosystem-oriented methods, i.e. biological control, cultural practices, natural products, resistant varieties, resistant rootstocks and minimal use of selected, mild pesticides. This approach ensures sustainability and minimises pesticide risk to human health and the environment. It can be applied alone or in combination with other ecosystem-oriented production practices, in the context of an advanced system of sustainable agriculture, known as integrated crop management (ICM). Studies to develop IPM/ICM systems were carried out on citrus, grapevines and on vegetable and ornamental greenhouse crops, in cooperation with other Sections of the Institute. Plant Pathology and Entomology laboratories provided support for the scientific identification of plant diseases and insect pests, in various samples provided by the Department of Agriculture, the Medical and Public Health Services, the Department of Forestry, agriculturists from the private sector and farmers. PLANT PATHOLOGY Programme for the control and characterisation of Citrus tristeza virus The main objective of the programme for the control of CTV, which was initiated in 1992, has been the systematic survey of all citrus and the removal of infected trees and/or groves wherever that is feasible. The survey has been conducted by indexing 10-20% of the trees of each grove and samples were tested in the Plant Virology Laboratory by Enzyme-linked immunosorbent assay (ELISA). Several isolates collected from different areas of Cyprus causing a wide diversity of symptoms were tested and characterised. Symptoms on field trees ranged from inconspicuous to twig die back, decline and death of sweet orange or grapefruit trees on sour orange rootstock. Similarly, on Mexican lime, symptoms ranged from barely noticeable leaf vein clearing to vein corking, stem pitting and plant stunting. Coat protein gene (CPG) amplicons were digested by a selection of restriction enzymes and characterised with single strand conformational polymorphism. The nucleotide sequence of the CPG was determined and phylogenetic analysis was performed. Results showed that most symptomless isolates from Cyprus clustered among the mild strains reported from Spain, Portugal and Africa. In addition, isolates that were responsible for decline of sweet orange, grapefruit and mandarin trees showed high similarity with strains reported in Africa (B249) whereas four other isolates that caused stem pitting symptoms clustered with T36, an American severe strain from Florida. The SSCP technique and the subsequent nucleotide analysis of the Cypriot CTV isolates enabled their clear distinction in mild and severe, their comparison to universal 41 Plant Protection