Palm Weevil
Class: Insects
Common Name
Palm Weevil
Scientific name
Rhynchophorus Ferrugineus
Potential Hosts
Palms
Who am I?
Palm weevil is an invasive species of beetle that poses a serious threat to palms trees; it is considered to be the world's most threatening pest to palms. Adult females are capable of flying long distances non-stop. A female can lay 250-300 eggs in her lifetime on cut or wounded palm-tree tissue. Palm weevil has the ability to knock down large palm trees that were completely healthy 6 months prior.
Symptoms
Damage to invaded trees remain invisible long after infestation. By the time the first symptoms appear, the larvae population inside the trunk had months to develop. Many times, the damage is so severe the tree will die, making any actions irrelevant.
Sometimes, early warning signs appear in the form of yellowing and wilting on the crown and upper leaves. In cities and populated areas, there are risks of collateral damage from collapsing trees.
The adult beetle is large and red colored. The spread of palm weevil is due to the lack of early-detection methods in large parts of the world, the importation of infested palms, and the movement of palms and offshoots from contaminated to non-infested areas.
Control measures
Cultural
Monitoring: Scout the trees in your field and look for the above mentioned symptoms.
Minimum Pruning: Avoid pruning as much as possible.
Monitoring traps: You can use specially designed monitoring traps for keeping track of palm weevils; check them regularly to aid with treatment decisions.
Consult your local distributor for the the type, timing, number, and positioning of the traps you have or wish to acquire.
Conventional (chemical)
Borers are by far the most difficult group to manage. Weevil larvae can excavate tunnels through the trunk up to 1 meter long.
The use of insecticides varies between countries and crops; one country may allow the use of a certain chemical, while another country may prohibit it.
Palm weevils behave differently with respect to different palm varieties. Control techniques change accordingly:
Ornamental Palm Trees Suggestions:
The weevil attacks upper parts by entering pre-opened leaves (spear leaves).
Some growers use a solution of 10 to 20 litres of water per tree and add 25 cc imidacloprid (350 gr\L), 30 cc cypermethrin (100 gr \L), and 0.2% tebuconzole (250 gr\L) sprayed or poured directly into the center of the crown once every 3 months (good for prevention and eradication).
In irrigated trees, it is recommended to apply the same recipe via an irrigation system.
Other Options (all applied by pouring or spraying directly into the center of the crown):
*Dinotefuran (20%) 25 grams or 0.2% concentration in solution and 25 liters per tree in spraying application
*A 15 liter solution 0.2% concentrate combined of imidacloprid (430 gr\L) and gamma cyhalothrin (30 gr\L) - apply every 3 months
*A 20 liters solution with 0.3% Lambda-Cyhalothrin (50 gr\L) and 0.2% imidacloprid (350 gr\L)
Date Palm Suggestions:
In date palms, the weevil attacks the lower parts of stems where offshoots emerge and the connection between them and the mother occurs.
Spray the lower stem parts, especially offshoots, with the above mentioned recipes, but take into account pre-harvest interval restrictions.
Quick Tips
Palm weevils are attracted to the scent of fresh cuts or bruises along the stem. As long as there are offshoot-bearing trees in your close surroundings, if infestation suddenly occurs, it probably started in those trees.
As a consequence of the previous info, after any act of pruning, make sure to apply a special sealing paste dedicated to diminish the spread of the scents and fragrances palm trees naturally emit due to tissue damage.
In some cases, the larvae population becomes so high that you can hear weevil activity by putting your ear on the stem.
Phoenix canariensis is known as a favorite host.
Note that reinfestation can occur in places where eradication was successful due to a single untreated tree.
Caution and careful notice should be taken when using any plant protection products (insecticides, fungicides, and herbicides). It is the grower’s sole responsibility to keep track of the legal uses and permissions with respect to the laws in their country and destination markets. Always read the instructions written on labels, and in a case of contradiction, work in accordance to the product label. Keep in mind that information written on the label usually applies to local markets. Pest control products intended for organic farming are generally considered to be less effective in comparison to conventional products. When dealing with organic, biologic, and to some extent a small number of conventional chemical products, a complete eradication of a pest or disease will often require several iterations of a specific treatment or combination of treatments.