The Red Palm Weevil

You may already have read the article, Where Have All the Palms Gone, elsewhere in this newspaper, and some of you will have read my comments in the online edition of my December column about this nasty pest. No apology from me if I am getting repetitive, as this is an extremely harmful pest. Here is some advice for those of you who have palms in your own garden.

Chemicals

Since this is such a difficult pest, any control measures will have to include the use of pesticides. Even these, however, do not guarantee success. It is very difficult to spot an infected tree before it is too infested to save it.

It is far better to use insecticide application as part of a preventative regime. In Italy and Spain they have been successful in getting on top of the pest by using pesticides.

Because the larvae of the beetle are burrowing away inside the palm it is very difficult, even with a translocated insecticide*, to kill them all with one application. As very few applications will stay effective for more than four weeks, it is better to carry out repeat applications at one-month intervals. It is also a good idea to use different chemicals to ensure resistance does not build up in the weevil population.

I’m sorry, but if you want to grow palms, and fight the spread of this pest, organic/cultural methods are not enough.

Cultural Methods

The female weevil prefers to lay her eggs wherever the palm is damaged and/or where there is a lot of debris to help hide her eggs. Cultural methods should then aim at reducing these niches.

Palm tree heads soon collect a lot of debris so it is imperative that they are kept as clear as possible. (Whilst doing this job keep your eyes open for evidence of chewed fibres at the leaf bases or weeping, smelly sap – both indicators of the presence of the larvae).

Dead leaves should also be removed regularly. Do not, however, cut them too close to the stem. It is better to cut about 15cm away from the trunk. Spraying the open cuts with a translocated insecticide should kill any females that try to take advantage of this potential entryway into the trunk.

When pruning, check that the leaves do not have the tell-tale bore holes running through them.

Disposal

Do not dump your prunings or dead trees in the garbage. You will only be aiding the spread of the pest. Why not call your local Demos and see if they have organised a safe disposal method? Failing this, the recommended way to dispose of infected trees is to bury them covered with lime. Burning is another option but, because palm trunks are so damp, it is very difficult to thoroughly burn and, therefore, kill all the bugs. This picture does not show a palm being wrapped as a gift, but a badly infested tree being wrapped to reduce the risk of weevils escaping before it is removed.

So you still want to grow palms?

Next month I will give advice on what you can do if you still want to grow palm trees.

Reader’s Query

Sheila Hollins has contacted me and asked if I know of any English language books that deal with vegetable growing in this climate. In a word my answer is, unfortunately, no. Can anybody else out there help out? I am sure we all would appreciate such a book. Any queries or tips can be sent to: www.quality-gardens-crete.blogspot.com.

*Translocated insecticide – an insecticide that is absorbed by the plant and is transported throughout its system, therefore being effective against pests that are not in contact with the originally sprayed area.