What are the signs of an infested palm?

Symptoms include holes in leaves, leaves that appear to be cut in a straight line with scissors, drooping leaf or leaves, dry leaf or leaves, vinegar smell, cocoons in trunk or wedged between leaves, old cocoons on the floor or you may just see lots of weevils flying around - they are attracted by other weevils.

Marbella Palm with Two Crowns

Last week I came across this wonderful palm. Usually a palm only has ONE region of growth (apical meristematic tissue) resulting in just one crown of leaves but this one must have suffered some damage, possibly by the red palm weevil larvae, resulting in a division of the region actively carrying out cell division.

Trapping Red Palm Weevil (Rhynchophorus ferrugineus) can help reduce and monitor populations

These traps are most effective burried in the ground, soil level with holes in the side.

Spring is here – well almost!  The temperature this morning, just before 9, is already 14^oC and the bees can be heard buzzing happily on some of the flowering shrubs.  They aren’t the only insects that get moving with the warmer weather.  The weevils are out there too.  I am, of course, talking about the Red Palm Weevil – the evil weevil destroying so many palms, young and old. We have caught 11 in my small trap over the past couple of days.  Not such a big catch compared to the 82 we found when the sun shone for a few days in January, but with all the rain and generally lower temperatures, the 11 is a sure sign that THEY ARE OUT THERE – and in their millions.  I have been trapping for over a year now, and this year am catching many more.  This could be because of the dreadful rain we had last year – or simply because there are more weevils about.

If You Don't Care Cut It Down Now !

It is alarming that some people still think that the red palm weevil can be dealt with by pouring washing up liquid over the crown. I suppose that this method was discovered by putting some liquid in a jar and adding a palm weevil Not surprisingly it drowned in the viscose liquid. The same would have occurred using a jar of water. In fact others treated their trees by putting a hose up into the crown and turning on the tap for several hours. Of course they may have been lucky and caught an adult weevil off guard and drowned it but it would not and could not affect the larvae inside the palm, which are the creatures that cause the damage.  Another myth that is still prevalent is that the weevils will not attack baby palms or that once a palm is infected it is to late to do anything about it.

The truth is that there are currently only three methods that could eradicate this plague from gardens and countryside. They are the use of insecticides applied either as trunk injections or crown drench. The ecological method of crown drench with microscopic parasites called nematodes. This is the preferred method in the writers view. Thirdly, the sad fact is that the weevils have no natural predators, therefore the use of traps is the only way to prevent the weevils from laying their eggs in a palm in the first place. These traps are not expensive and use two attractants to the weevil called kairomones and pheromones. These are placed in the container and in conjunction with either a poison tablet or 20mm of water will quickly see the demise of all who enter.

A palm can survive after infestation if spotted and treated in time. Regardless of this an infested palm should be treated whether or not it has any chance of survival. The reason being that each female weevil is capable of laying three hundred eggs and if the three hundred eggs develop into 300 adults of which, lets say 150 will be female. In three generations and each generation occurs every 4 months  more than a million  new weevils will have entered the environment.

One now associates palms with our Mediterranean climate and this has been so for several hundred years. To devoid our environment of the beautiful palms would be a shame on us all. Judging from the experience of the Canary Islands it is possible to get this plague under control but it will take the will of all concerned to achieve this goal. You don’t have to have a palm to have a trap and you could add to the fight against the weevil. If you have one of the palms most at risk, such as a Canary palm, but have no intention of treating it (it is not a question IF it will be infested but WHEN will it be infested) be considerate to your neighbours and have it cut down now!