Friday, 16th December, 2016
Olive Quick Decline Syndrome
Alfred E Baldacchino
Mid-October 2013, saw Xylella fastidiosa, the olive quick decline syndrome (OQDS) recorded in Italy: its first record for Europe. By April 2015 it had infected up to a million olive trees, many of them century-old, in the southern region of Apulia. This invasive disease is believed to have been introduced by ornamental plants from Costa Rica, where it is also causing havoc.
By July 2015 it quickly spread to Corsica, in municipalities of Nice, and Mandelieu-la-Napoule and by late October in Alpes-Maritimes in France. August 2016 saw it in Germany infecting oleander plants.
November 2016 found OQDS in the Spanish island of Mallorca, in a garden centre on three cherry trees and an oleander.
OQDS is regarded as the most harmful plant pathogenic bacteria in the world. It infects grapevines, peaches, citrus, oak, sycamore, and many other trees and ornamental plants, such as spurge, lavender and rosemary. No cure has yet been found for such disease, as the European Food Safety Organisation has warned.
European and Mediterranean Plant Protection Organisation (EPPO) had since 1981 listed it on its A1 list of pests recommended for regulation as quarantine pests, regarding it as representing a very serious threat for the EPPO region
Across Europe, 359 plant species have been identified as susceptible to Xylella. Many of these species show no symptoms of the disease, and provide a reservoir for reinfection of other plants, thus making Xylella difficult to control and making phytosanitary certificates useless
This bacterium thrives in the water-conducting vessels (xylem) of plants. It invades these vessels and blocks the transport of water and other soluble mineral nutrients. This leads to the drying, scorching, wilting of the foliage, and eventually the collapse and death of the tree.
It spreads with the help of insects such as leafhoppers and spittlebugs, which feed on the plant xylem. These insects do not fly long distances, but can be helped by the wind, by other animals, and by vehicular transport.
Spain and France were deeply concerned when Xylella was recorded for the first time in 2013. Their production of olive oil and wine is under a great threat. The matter was also raised at European Union level.
Italy is heavily affected, considering that the only method to date to control such disease is by eradication of the infected million olive trees. These contribute to 40 per cent of the olive oil produced in Italy. Besides the economic loss, the social and ecological impacts are beyond any estimate.
Malta is blessed that it is an island surrounded by an expanse of sea that makes it impossible for these xylem-feeding insects to arrive naturally. But… it seems that we never learn.
Palm trees were imported for landscaping purposes from areas known to be infected by the Asian red palm weevil. More than 5,000 palm trees have been lost to date. Timber introduced the African long-horned mulberry beetle, which besides killing most of the mulberry trees in the islands, now has turned its attention to the white mulberry, carob and fig tree.
Imported geraniums by garden centres have also helped to introduce the geranium bronze butterfly from South Africa. All of these have been introduced by trees and plants carrying a phytosanitary certificate from the country of origin, to confirm that they were all disease free. How many imported tomato seedlings accompanied by a phytosanitary certificate, introduced the South American tomato moth (Tuta absoluta)?
Trees and other plants mainly, for landscaping and ornamental purposes, are still being imported from countries which are infected with this OQDS.
The Ministry for the Environment is responsible to ensure that such invasive species and other pathogens are not introduced in Malta, both through the Environment and Resource Authority, and also through its Parliamentary Secretary responsible for the Department of Agriculture. Once there was a renowned experimental farm at Għammieri, which today is more concerned with domestic dogs, cats, and birds.
A very good animation video has been produced by the Plant Health Department. Very good. What is needed now is urgent action.
Environmental responsibilities are far from being helped by the Ministry of Landscaping. Doors are flung wide open for exotic species to be planted in ‘landscaping’ projects, paid out of public funds, administered through an €8 million yearly budget, according to a secret agreement which, despite the Commissioner for Data Protection’s ruling, is still being withheld.
If Xylella were to make a foothold on this island, the price that society and the environment will have to pay is beyond any imagination
Those handful of pro-business politicians and their acolytes might ask if they are expected to stop the importation of exotic species. The question is whether such politicians are worried, not only for the young developing olive oil industry in Malta which is trying hard to acquire an EU/EC Declaration of Conformity (DOC) for CE Marking, but also for the wine and citrus industry. And naturally the islands ecosystem which if, God forbid, Xylella were to make a foothold on this island, the price that society and the environment will have to pay is beyond any imagination.
Prevention is better than cure, especially when there is no cure at all. That would be the day when one can honestly boast of a sound environmental policy. From experience, political action in this regard will only be considered when the social, economic and environmental fabric have bit the dust, or as it is said, when all the horses have bolted.
Alfred Baldacchino is a former assistant director of the Malta Environment and Planning Authority’s environment directorate.