It would be good to be able to tell you that the rhynchophorus ferrugineos is totally controllable but, unfortunately for palm owners and palm admirers, the news isn’t that great!
Over the last decade or so, a great deal of research and experimental work has gone on with various chemicals to try and find something that can control this pest. Unfortunately, there doesn’t seem to be a definitive answer. Trees have been sprayed with some very dangerous mixes of chemicals and, whilst they may have offered some form of control, they certainly have not stopped the chomping larvae. Individual trees are often missed during spraying programmes and, because the larvae are inside the trunk, they can be impervious even when the chemicals are injected into the trunk. Environmentalists are up in arms because of the toxicity of some of these chemical cocktails; a solution, and one that is friendlier-to-the-environment, is badly needed.
It appears that the beetle is more likely to attack newly planted trees or those that have been badly or overpruned. By this I mean pruning which has left ragged edges and/or the pruning away of too many leaves. A palm tree should always have an elegant drooping silhouette; those that are pruned to a funnel shape are overpruned. Remember that trees need their leaves to produce their food so over zealous pruning means that the tree cannot properly sustain itself, becomes weak and is susceptible to attack. At one time advice given by the Junta de Andalucia was not to prune the palms butI’d tend to disagree on this one – an untidy tree with lots of debris invites and encourages pests and infection. But do your pruning during the cooler months when the beetle is not so active. Keep your tree clean and tidy and growing strongly by appropriate feeding and watering – this is the first and most important preventative measure.
Interesting research work in Israel has shown that an infected tree gives off a pheromone or chemical signal and it is this that draws in more adult beetles. Sniffer dogs, too, can detect this ‘perfume’ and, thus, infected trees can be identified and destroyed before the beetles can spread and invade other palms. This same pheromone can be artificially created and a palm can be doused in the smell to act as a lure – rather like beer traps are used to entice slugs to their death. I have heard recently that the same approach is being trialed in Spain. A natural lure like this is, of course, far more beneficial to all than the toxic chemical approach.
For us home gardeners the brightest hope seems to be neem oil. I’ve sung the praises of neem oil before as a wonderful preventative. The makers say that regular spraying with neem can prevent attack by the palm beetle – an application every two weeks at the rate of 1cc to 1 litre of water. It’s a small price to pay to protect our palm trees. If you believe your palm is already infected, the recommended course of treatment is 1 litre of neem to 20 litres of water and a thorough dousing of the foliage and trunk of the palm. Large palms will need a greater quantity of the solution.This should be repeated every two months until the tree seems to be clear. This is only useful in the early stages of infestation, once the larvae are well ensconced, they seem to be unstoppable. Neem is not a cheap operation, but a mature palm is virtually irreplaceable, both from an aesthetic and cost point of view. I have clients who are trying a lesser dosage and they have reported seeing dead beetles after treatment. It’s all new and experimental so there are no sureties but I’d rather go the organic neem route than using strong concentrates of chemicals which could be causing unknown harm. I have stocks of neem oil at the garden centre and I’d be happy to give any advise I can on diagnosis and treatment.
As I mentioned last month, the Town Hall should be notified of any infected palm. They should react quickly to try and break the chain of infestation. The only correct approach is to chop the palm into sections, bag it up and cart away for chipping. This is a free service. Never try to burn the tree as the beetles will fly to new food sources.
As I’m writing this article, I’ve received an email from a customer. Five weeks ago he came to me with photos showing a poorly palm tree. I told him it looked bad and probably couldn’t be saved. Five weeks later, on his return to Spain, this is his devastated palm tree. He has kindly given me permission to use his photo. It’s a very sad ending to a once magnificent palm tree.
You may or may not believe in the Christmas story, the birth, the presents from the three kings, the palm trees ever omnipresent. Certainly, palm trees are one of the oldest fruiting trees known to man and there are some 100 million worldwide. They are tough but elegant survivors. Let’s hope that they can.
A very wonderful festive season to you all.
Lorraine Cavanagh is the author of Mediterranean Garden Plants.
Her plant nursery, Viveros Florena, is on the Algarrobo/Cómpeta Road, 15km up from the coast. Look out for the flowerpot lady. Opening hours Tuesday to Saturday, 10am – 6pm. Also, catch her weekly show on OCI radio.
Tel: 689928201 florenaspain@hotmail.com
