Pest and Diseases and Main Control Strategies of Greek Olive Groves

Olive crop in Greece is attacked by diverse pest species. The olive fruit fly (OFF), Bactrocera oleae (Gmelin) (Diptera; Tephritidae) is the major insect pest affecting olive plantations of Greece, resulting in a decrease of the olive yield and lower quality of the extracted olive oil, which might lead to a reduction of the economic profitability. The degree of infestation is high; about more than 90% of orchards can be infested by the OFF in absence of treatment and under optimum climate conditions for the development of the insect. Bactrocera oleae control in Greece is mainly based on insecticides particularly organophosphates, pyrethroids and spinosyns as bait applications (3–5) as well as cover sprays (1–3) and rarely mass trapping. However, pyrethroid resistance has been developed in populations of B. oleae from Greece. Other olive pests that could cause damage of major economic importance from time to time include olive moth Prays oleae (Bernard) or the black scale, Saissetia oleae (Olivier), which their control is based only on cover sprays with registered insecticides. Moreover, olive trees are commonly affected by a wide range of diseases that may occasionally cause severe yield losses and tree death in major olive-growing regions in Greece. Among them, fungal diseases such as Verticillium wilt, olive leaf spot, Cercospora leaf spot, olive anthracnose, olive fruit rot and the bacterial olive knot disease are the most predominant, whereas others like esca or other wood decay-associated diseases are considered to be emerging diseases for the Greek as well as for the Mediterranean olive industry. In most cases, complete eradication of such diseases is practically unfeasible. However, when olive diseases are early identified and recommended treatments properly applied, they can be controlled efficiently. Herein, we provide a brief description of dominant pests and diseases in terms of their impact, incidence (mainly for pathogens) and distribution across the major olive-producing areas in Greece. Moreover, we present the basic management practices that are commonly suggested and applied by the Greek olive growers.