Olive anthracnose. Typical symptoms of soft nose on olive fruits attacked
by Colletotrichum gloesporioides with clear fungal acervuli.
Abstract
The economic, social, cultural and eco-environmental importance of olive growing in Italy and the other Mediterranean countries, coupled with the maintenance of existing olive orchards and the spread of olive cultivation to new areas or its introduction in areas outside Europe, makes it necessary to pay close attention to crop phytopathological problems and to update the cultural and epidemiological aspects of plant pests and diseases on a continuing basis.
This paper describes the current phytopathological problems in olive, including in the light of climate change. It shows how these problems can affect the re-emergence of diseases that are already known and focuses attention on newly emerging threats, besides informing on the latest eco-sustainable integrated protection strategies.
Introduction
The very differing scenarios found in olive growing across Italy may be the key to its loss of competitiveness. In Italy, unlike in Spain, olives are still grown on marginal land although in some parts of the South this may be the only option open. Some weak points such as the
small average size of olive farms – 70% are just under 2 ha – are offset by strong points such as the extensive range of varieties even although only 10 or so are found nationwide, accounting for 475,000 ha or approximately 42% of total olive area (Madau, 2009).
The most notable of these varieties are ‘Coratina’, ‘Ogliarola Salentina’ and ‘Cellina di Nardò’, which are grown widely in Apulia, and others such as ‘Carolea’, ‘Frantoio’ and ‘Leccino’, which
are cultivated in a large part of Italy. However, although grown on a very limited scale (between 1,000 and 10,000m2), at least another 100 varieties are a valuable resource because of the characteristics of their fruit for table consumption or the quality of their oil. They are particularly valuable in the search for new sources of resistance to the main biotic threats to olive production as well as in the drive to orient olive cultivation towards more suitable areas more readily adaptable to the different soil and climatic conditions found in Italy.
This paper follows on from an earlier paper published a decade ago (Tosi and Zazzerini, 2005). It intends to provide an update on the phytosanitary status of the olive with the focus on two known plant diseases – verticillium wilt, a vascular disease that is still difficult to combat, and anthracnose, considered to be a minor disease but attacks of which have recently become more intense in some olive growing environments – and two emerging pests/diseases. The review then aims to show that the development and adoption of control measures must be accompanied by up-to-date knowledge of agricultural crop practices which, when they change, affect the olive agrosystem and have repercussions on the incidence and severity of pests and diseases like those mentioned above.
Modern pest and disease control such as that required under Directive 128/2009/EC, which has been worked into Italian legislation in Decree Law 150/2012, takes a broad and systematic approach to the aspects of the impact of agricultural chemicals on the environment and food healthiness. The National Action Plan (known by the Italian acronym PAN) introduced on 1 January 2014 maps out the general principles of integrated plant protection, which is now compulsory, and makes provision for two levels of application (integrated protection
and organic agriculture). In short, in the new regulation, plant protection is prevention-based. It entails synergically harnessing the potential and distinctive features of the various forms of control in order to ensure comprehensive crop protection instead of limiting protection to
containing a single plant disease and to take immediate action when new pests emerge (for instance, olive quick decline syndrome). Hence, rational crop protection calls for continuing, constant updating of knowledge, technologies and techniques and ever increasing integration
of different fields of expertise.
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Olive bark beetle. Frass indicates the presence of the beetle in the area under
the bark (A) and feeding galleries (B).