We are passionate about plants!
The Palm Beetle, rhynchophorus ferrugineos, or Sp. picudo rojo. Part 1
The palm tree is, to most of us, one of the most potent symbols of our Mediterranean lifestyle. We love it – in our gardens, by our swimming pools, in parks, grouped on our beaches and lining our promenades – our whole coastal landscape would be very different without it. Many have been around for two or three hundred years. So, I know that the invasion of the palm beetle is worrying lots of you and causing immense headaches to the local authorities.
This rather handsome looking beetle arrived on our shores in 1994 via a shipment of palms from Egypt to Almuñecar, on the Costa Tropical, from where it has spread rapidly. Through the last twelve years or so it has reached almost all parts of mainland Spain and her islands, chomping away at our palm trees as it advances. The devastation is enormous and preventative measures seem to have been somewhat ineffective to date.
The beetle originates in South East Asia and Polynesia, where natural predators keep it somewhat under control. It was originally thought that it only infected the phoenix canariensis, the phoenix or Canary Isle palm and phoenix dactilyfera, the date palm. However, research has shown that, whilst these are their preferred food source, they will also inhabit Washington palms, washingtonia robusta and filifera. These palms are the ones that are most commonly planted – the rib-leafed palm and the fan-leafed. There are others that are cold hardier, but these stand up to coastal winds best and are relatively quick growers. However, we should not get complacent about any of our palms as there are various species of these beetles which will invade almost all with equally devastating consequences. The only commonly grown palm that seems to be immune to their attentions is our native dwarf fan palm, the chamaerops humilis.
The date palm is one of the oldest fruiting trees known to man. There are about 100 million worldwide, of which 62 million are found in the Arab world. They generally live to a grand old age, around 300 years, and start cropping at 5 years of age.
Spain has an immense heritage of palm trees. The Canary Isles have their own endemic species – it is a symbol of the Islands and it would be an environmental disaster if it were lost. Elche, known as the City of Palms, in Valencia province, has the largest palmeral in Europe, an immense forest of palm trees. The Phoenicians first planted them there, finding the weather conditions perfect for the crop that they so valued for their long sea voyages. During Muslim occupation, the farming was intensified to around 1,300,000 trees. Elaborate irrigation systems were installed to maximise the crop – Elche reached its peak. In 1240, Ibn al-Yasa said: "There are no dates in Al-Andalus as good as those of Elche". But, after the re-conquest and by the end of the 19th century, the number of palms had been reduced by half, mainly through non-replacement. The 20th century saw more being cleared away for land clearance and development. Traditional houses in that area used palm trunks in their roof structures and as pillars on verandahs etc. In 2000 UNESCO declared the palm plantations of Elche a World Heritage Site – a unique opportunity to see Arab agricultural practices and irrigation systems in Europe. But, in 2004 the palm beetle reached Elche and in spite of extreme measures and all precautions, one thousand examples have been lost to date.
To give you some idea of the scale and spread of the thing, in the early days of the problem, in Chipiona, Cadiz province five infested trees were detected. Within three months, the authorities were looking at cutting down some six hundred blighted palms.
Initially thought to be only a coastal problem, there are now infected palms inland too. The colder temperatures in hillside towns and villages do seem to form some sort of control but, once a tree is infected, the larvae and beetles will live off it until there is no more suitable feeding material. Inside, the palm becomes a perfect breeding site for future generations - hot and humid. And then the females will fly on to new breeding grounds.
Next week, I’ll tell you how to recognise the palm beetle and their offspring, how to identify an infested tree and what measures we can take to control the spread.