Paysandisia (Paysandisia archon)

Paysandisia is one of the most dangerous pests of palm trees

In recent times, palm trees have become the main victims of very dangerous insects: one is the Rhinchophorus ferrugineus, better known as the red weevil, and the other is the paysandisia archon, which is what we are going to talk about in this article. And, although both must be kept away from our plants, the latter also attacks young specimens that have not even formed a trunk yet; hence its prevention is even more important if possible.

Knowing its characteristics and its biological cycle will be very useful to us so that the treatment (be it preventive or curative) is really effective. So let's go.

Origin and biological cycle

Paysandisia goes through different phases before reaching adulthood

La paysandisia archon, known simply as paysandisia, is a moth native to Paysandú, which is a town in Uruguay. It goes through different stages, from an egg to a moth that looks like a butterfly:

  • Eggs: they are pale pink in color and measure about 5mm. They are similar to grains of rice.
  • Larvae: As soon as they come out of the egg they are orangey, but as they grow they turn creamy-white in color, about 6cm long.
  • Pupae: they are reddish brown in color and are protected by a silky cocoon made with fibers from the plant itself and excrement.
  • Adults: they measure up to 10cm. They have two pairs of wings: the previous ones are brown-olive with lighter transverse stripes, and the later ones orange with two black bands. The female lays her eggs -sometimes up to 300- in the axils of the leaves as soon as the temperature is warm (20ºC or higher).

What do the larvae feed on?

The larvae, as soon as they are born, dig galleries in the trunk, feeding on it. In doing so, what happens is that it destroys the vascular system of the plant; hence it is so difficult to recover it once it has been infected. But as we will see below, there are many things we can do to not lose it.

What are the symptoms and damage it causes?

Leaf holes are common symptoms of paysandisia

Image - iwcpgardeninggroup.blogspot.com

Identifying this pest is not difficult, because causes characteristic damages, which are:

  • Leaves with holes that, when opened, form a fan
  • Fibers protruding from the stipe (trunk of the palm tree)
  • Holes in the stipe
  • Loss of vigor
  • Rapid yellowing of the leaves
  • Growth arrest
  • Secondary infections
  • Premature aging
  • The central blade, which acts as a guide, deviates
  • Production of flowers and fruits (this may sound a bit strange, but it must be borne in mind that plants, when they are about to die, produce flowers with the intention that they are pollinated. Thus, they ensure that a new generation can take his place)
  • And finally, death of the palm tree

Keep in mind that all these symptoms can appear in a short period of time. I can tell you myself that I saw a palm tree die in a private garden in about 4-5 months.

What are the most affected palm trees?

All palm trees, of all species, can end up being victims of paysandisia. It is true that it affects the Phoenix (so much P. canariensis as P. dactylifera) already chamaerops, but that is because they are one of the most abundant species in our cities and towns. As soon as they start to run low, we will see that they will go for the washingtonia, Dypsis, Roystonea, ... and ultimately, for all the others.

How is it treated and / or prevented?

Once the symptoms have been detected, or if what you want is to prevent, what you have to do is treat the palm tree for one month with chlorpyrifos and the following month with imidacloprid, from early spring to autumn, following the recommendations indicated on the product packaging.

Preventive remedies

Nematodes can prevent a palm tree from dying from paysandisia

Image - Elnortedecastilla.es

Paysandisia is a potentially dangerous pest. If we want to prevent our palm trees from having problems, it is very important to take into account the following:

  • Do not prune in summer: There is a bad habit of pruning these plants in summer, which is when they are growing the most and when the pests are most active. By doing so during that season, all you do is put them more at risk. Therefore, it is necessary to prune in early spring or autumn.
  • Prune too much and / or poorly: as bad as pruning when it should not be done badly. And it is that you only have to cut the dry leaves, never the green ones. In addition, the cuts must be clean, without tears.
  • Direct the water to the eye of the palm tree: this can only be done in summer. By directing the irrigation water to the eye, the aim is to drown the larvae. It is not 100% effective, since some larvae may remain, but it is controlled.
  • Apply nematodes: of the species Steinernema carpocapsae. They have to be mixed in 10 liters of water, and apply every month and a half approximately (it will be indicated on the container).

And with this we are done. Hopefully it has been useful to you. 🙂


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