Bacterial Plant Disease

Primary reference(s)

FAO, 2018. 2017: The Impact of Disasters and Crises on Agriculture and Food Security. Food and Agriculture Organization of the United Nations (FAO). Accessed 31 October 2020.

Additional scientific description

A bacterium is a single-celled, microscopic organism that lacks a nucleus. Some bacteria cause animal or plant diseases (University of California, 2019). Plant diseases caused by bacterial pathogens place major constraints on crop and forest production and cause significant annual losses on a global scale (Sundin et al., 2016).

The Food and Agriculture Organization of the United Nations (FAO) estimates that each year, plant diseases cost the global economy around USD 220 billion (FAO, 2019).

Numerous bacterial diseases affect crop production in many countries and regions. These include fire blight in fruit trees, bacterial wilt in banana, bacterial blight in rice and crown gall in many perennial plants. In some cases, the epidemics caused by bacteria can cause significant economic burden on crops (FAO, 2018).

For example, Xylella fastidiosa is a bacterial disease with many subspecies that in recent years has managed to establish itself in areas along the Mediterranean coast, where it is attacking economically important crops such as olive, citrus, stone fruits, grapevines and forest trees such as oak (FAO, 2020).

• In 2013, Italian researchers made a troubling discovery: one of the world’s most destructive plant diseases, normally found in the Americas, had made its way to Italy’s olive trees. With no known cure, the pathogen has already affected more than 10 million trees in the south-eastern tip of Italy. If not properly contained, it threatens to spread across the entire Mediterranean basin. The Italian government contracted national research institutes and the International Center for Advanced Mediterranean Agronomic Studies (CIHEAM) to survey and contain X. fastidiosa. Other Mediterranean countries are at great risk if the disease spreads further (FAO, 2020).
• The disease threatens to spread to the Near East and North Africa region. To help smallholders protect their crops and livelihoods, the FAO is supporting efforts in Near East and North African countries to raise awareness of the threat and implement technologies and techniques that can help prevent, detect and contain this deadly disease (FAO, 2020).
• Not only olive trees but also more than 500 other plant and forest tree species are hosts for the various strains of the bacterium. If not prevented, smallholders in the Near East and North African region could have their livelihoods devastated and national economies destabilised by the potential spread into the region. Because of these risks, the FAO has launched a project to support Near East and North African countries in their efforts to prevent the introduction and spread of this disease (FAO, 2020).

Metrics and numeric limits

Not available.

Examples of drivers, outcomes and risk management

Although most bacteria existing in the soils and natural environments are beneficial, some cause significant diseases in plants under favourable conditions. Disruption of ecosystems and negligence of crop hygiene contribute to the build-up and spread of the inoculum of bacteria, causing substantive economic damage to crops and natural habitats. Prevention of spread is always easier than responding to outbreaks and control. Control of the diseases caused by bacteria is achieved by following the principles of sustainable plant production and integrated pest management practices.

Disease management approaches include focusing on diversified productions, use of pathogen-free certified planting materials, use of resistant varieties, regular surveillance, crop and forest hygiene and rapid containment and response at initial stages. Some bacteria are transmitted by insect vectors; thus, control of these vectors is important for disease management. Bacteria in agricultural environments can mutate and produce new strains that might be more aggressive than before. Therefore, monitoring and development of resistant varieties to emerging strains is critical for integrated management of the diseases caused.