Recently, newspaper articles flooded the news about the appearance of a dangerous disease that destroys olive trees in the Apulian province of Lecce (south-eastern Italy). The bacteria Xylella fastidiosa, which hails from the Americas, has infected trees across 74,000 acres of the region of Puglia and is spreading rapidly. Deadly, insect-borne bacteria destroying olive groves could devastate Italy’s olive oil industry.
In Italy the bacteria appeared suddenly in 2010 and a devastating disease denoted Olive Quick Decline Syndrome (OQDS). Symptoms consist of withering and desiccation of scattered terminal shoots, which rapidly expands to the rest of the canopy, and results in the collapse and death of the tree. Xylella fastidiosa is a xylem-limited Gram-negative bacterium and the causal agent of a number of severe diseases, among which Pierce’s disease of grapevine, leaf scorch of almond, oleander and coffee, citrus variegated chlorosis, and other disorders of perennial crops and landscape plants.
The bacterium is transmitted persistently by xylem-sap sucking insect vectors, mainly sharpshooters and spittlebugs (Cicadellidae). Once infected with X. fastidiosa, insects remain infective with the pathogen, which multiplies in the foregut and the bacterium becomes persistent in adult insects.
Diseases incited by X. fastidiosa occur mainly in tropical/subtropical areas, although leaf scorch diseases also occur in much colder climate, e.g. oak leaf scorch up to Canada. In 1994, it was first noticed in Asia, in Taiwan causing leaf scorch on Asian pear (Pyrus pyrifolia). In the 2000s, it was also reported causing Pierce’s disease in Taiwanese vineyards. In the EPPO region, the recent finding in Puglia (Southern Italy) represents the first confirmed detection in Europe.
EPPO region: Italy (introduced in Puglia, under eradication).
Asia: Taiwan (introduced, first found in Asian pears and then in grapevine).
North America: Canada (Ontario), Mexico, USA (Alabama, Arizona, Arkansas, California, Delaware, District of Columbia, Florida, Georgia, Indiana, Kentucky, Louisiana, Maryland, Mississippi, Missouri, Montana, Nebraska, New Jersey, New Mexico, New York, North Carolina, Oklahoma, Oregon, Pennsylvania, South Carolina, Tennessee, Texas, Virginia, Washington, West Virginia).
South America: Argentina, Brazil (Bahia, Espirito Santo, Goias, Minas Gerais, Parana, Rio de Janeiro, Rio Grande do Sul, Santa Catarina, Sao Paulo, Sergipe), Costa Rica, Paraguay, Venezuela.
For situation in Italy the European Union has approved reinforced measures to prevent the spread of Xylella fastidiosa. The Commission says at least 10% of the 11 million olive trees in Lecce are infected. It wants Italy to destroy infected trees and restrict any trade in species vulnerable to the disease.
As chemical curative control of the bacterium is not possible, management of diseases caused by X. fastidiosa in the countries of origin concentrate on prevention, by use of resistant varieties, cultural and hygienic measures and chemical and biological vector control.
The measures for suppression of the bacterium are:
Principles on how to suppress the bacterium in other cultures that it attacks and what measures to take to prevent a complete loss of yield and the whole farm, you can find in the Agrivi farm management system.
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