This stand of palm trees is in the front garden of the former residence of the Saudi Ambassador on Via Regina Margherita. They appear healthy but only today an infected tree was removed that stood beside them. It was first stripped of all its dead fronds, then the top cut off and the trunk cut into pieces. Hopefully it has not infected the other trees but by the time the trees show distress it is normally too late to save them.
Palms are not native to the area but were imported in the 19th century as an exotic plant for the gardens of the villas that surround Roma. And since 2004 more were being imported into the coastal towns by municipal governments eager to sell their areas as lush tropical tourist destinations. And those trees - most imported from Egypt - served as a Trojan Horse (if I may mix historical metaphor) for a small, well concealed but dangerous enemy. The culprit is a little insect known as Rhynchophorus ferrugineus or the red palm weevil. And it is proving deadly for those palms ( Phoenix canariensis) that line the streets and grace the villa gardens and parks throughout the city.
So far this tree in an apartment yard on the Aventino (top) has not shown any signs of infestation and appears to be healthy as does this tall palm near our house. It has become a host but to a wisteria that is climbing its way up - perhaps ultimately as destructive as the weevil but more easily controlled.
As with many insects it is not the adult weevil which is the destroying agent but the larvae which burrow their way into the heart of the palm. A female weevil lays as many as 300 eggs and the hatched larvae then tunnel through the plant feeding on the soft interior fiber. In a serious infestation if you put your ear against the trunk it is possible to hear the crunching sound of the feeding larvae.
As recently as last year this palm in our neighbour's yard (top) was gloriously healthy looking - it has now been in its present state for about 6 months. The law requires that people report infected trees on their property but infestations often go unreported because of the cost of removal etc. The palm in the second photo, at a house just down the street, is showing the first stages of the handiwork of the weevil larvae. It is probably too late to save it now.
By the time the top leaves show signs of drooping it is already too late to do anything. In a little as three months the palm will be dead. Because it is not indigenous the weevil has no natural enemies in the region and few of the eradication/control methods used have proved successful. It would appear that the best way is the most drastic: cut down and shred all the palms, including the healthy ones, in areas where infestations have been found. Though the law requires that people report sick trees on their property many people neglect to because of both the drastic measures necessary and the cost involved.
Though the situation is a serious one quite often plants have a way surviving. This palm has taken root on a long dead tree on a nearby street - another example of the remarkable tenacity of plants.
Italian scientists are attempting to find a solution but the fight is an unequal one. The Trojan Horse was willing dragged in from the outside world, it disgorged its troops and caught the inhabitants by surprise. The original story had a sad ending - it may well be the same for the beautiful Palms of Rome.
08 aprile - San Dionigi di Corinto