The March of the Palm Beetle

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In 1994 the palm beetle, rhynchophorus ferrugineos,or picudo rojo in Spanish, arrived in Spain. I last wrote about it in November 2007 so I think it’s time for an update.

Sadly, the news isn’t very good. Every day in the garden centre I give advice to, at least, one more gardener with an infected tree and I get many emails and phone calls from further afield. Close to home, if you’re living in the Archez/Canillas/Cómpeta/Sayalonga area, I’d say that the situation is grave. Hugely elegant palms are collapsing - a great loss to our gardens and our landscape.

Some facts: the beetle was originally introduced, and is still being introduced, from Egypt. In Spain almost every urbanisation, promenade and golf course has its share of waving palm trees. Demand has been so great during the building boom that, during 2004 and 2005, 100,000 Egyptian palms were planted. It is now suspected that many of those were already infected. Strange, given that the importation of palms from Egypt was prohibited in the year 2000. But importers protested and the administration wavered and gave in. Their reasoning was that the same palms were still arriving in Spain but via Italy or France. Here’s a fact that may surprise you. A large palm, in Egypt, will be sold for, say, €60; by the time it sells in Spain, that price tag will have gone up to €500. So now you begin to see a large part of the problem …..

In 2007, the Junta de Andalucia invested 1.8 million euro in the battle of the palm beetle but, given the numbers involved, it’s a drop in the palm beetle ocean. Some 20,000 palms have been destroyed, to date, in Andalucia alone and Málaga capital is now under attack from the red devil. As is often the case, internal squabbling stops action. Málaga Town Hall complains that they have already spent 700,000 euro in a two year battle in which time 100,000 palms have been destroyed in the Capital. They claim that the responsibility rests with the Junta; that the Andaluz people, as a whole, should be paying to look after their capital city.

Certainly, on a more local level too, you’ll get little help from local Town Halls judging by phone calls I have received from far and wide. Affected trees should be reported to your local Town Hall, as the Junta are trying to keep a record of the path and numbers of palms infected. But disposal of rotting trees will be largely left to individuals. These should, correctly, be cut down in sections, bagged up and shredded so that the beetles cannot fly to infest other palms.

So, as the beetle has been on our shores for 15 years, what has been done?

Previously, the plan of attack was almost entirely with chemicals. Some lethal cocktails have been applied over the years – to the detriment of public health and, probably, many other insects and animals – and to little effect. A biological and environmentally-friendly approach is now taking centre stage and there are several prongs to the attack.

Firstly, sensors have been developed that can detect the movement of the beetles and grubs at night when they are most active. Thus the degree of infestation can be gauged. This is important in deciding whether it may be possible to save a tree or if the attack is too advanced for remedial measures.

Feromine traps are now more sophisticated. These emit an odour which attracts the beetles, and traps them for killing by whatever means appeals to you most! (They’re said to be very good lightly roasted!)

But the latest methods, and those that I like best, are treatments with nematoides or fungi. Let me explain.

Nematodes are micro-organisms, like tiny worms, that parasite on living beings – specifically, in this case, steinernema carpocapsae which live on the grubs of the palm beetle. It is sold in a two-part pack, a powdered mix of the micro-organisms which is to be diluted with an application liquid and applied over the whole tree and soil area underneath. Special ring application tubes are available for installation on large palms.

The fungi, beauveria bassiana, naturally occurs in the ground and it is parasitic. The fine threads enter the body of the grubs and feed upon them until they die. It is harmless to other animals and humans. It is claimed that within 4 days 90% of the grubs are killed and within 24 days, the success rate is 100%. Furthermore, and perhaps more importantly, it protects the palm for a further 4 months.

I have to stress that there is still no definitive answer to the plague. These methods are still being field tested. The nematodes are expensive and not entirely proven. The fungi are still being field tested and, as far as I know, are not yet available to private gardeners.

The feeling is that all the answers will come too late. Numerous surveys have shown that the beetle largely prefers phoenix canariensis, by some 96%, with phoenix dactylifera, the date palm, coming second at 4%. When there is no other food source, the beetles have been seen to attack the Washington palm, Washingtonia filifera – a strong warning.

All the experts agree that prevention is, by far, the best course. Water and feed your palms to keep them growing strongly and healthily – beetles always go for weaker examples first. Do not prune green leaves – the smell exuded attracts the adult beetle. Old, dried out leaves can be pruned off, rather than leave lots of litter, but, even this, is best performed during the winter months when the beetle is far less active. Act responsibly if you have an infested tree to avoid dispersing the beetles. And, most importantly, treat your palms with a preventative. We sell Neem oil; used regularly it helps prevent attack.

If you want to learn more about the life cycle of the palm beetle, please check out Grapevine’s web page and my articles, Campo Cuttings.

 

Lorraine Cavanagh has lived in Spain for 23 years; a mother, grandmother and hispanista, her passions are plants, the environment, food and drink, and travelling within Spain. A landscape gardener and writer, she’s always happy to give advice. Call and see her at Viveros Florena, 2km from Cómpeta down the Sayalonga Road – have a free coffee and cake in their tea-rooms.
Hours:    October – May, 10 – 4, closed on Sundays and Mondays. 

Her book Lorraine Cavanagh’s Mediterranean Garden Plantshas been nicknamed ‘the bible’. The new edition at €24.90 is now generally available throughout Spain.
Tel: 689928201     E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

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