One of the most insidious pests on our succulents is the spider mite from the family of Tetranychidea. Some species of cacti and succulents are particularly prone to infestation by spider mites, the damage is obvious and the infestation is rapid.
spider mite infestation©Cactus Mealy.de
Infestation on cacti.
Particularly affected among the cacti are Aporocactus, Chamaecereus, Echinocereus, Rebutia, Lobivia, Matucana and Echinopsis. The main culprit is called Brevipalpus rulus, the so-called cactus spider mite, which does not weave spider webs, as the name suggests. It causes its damage in the vertex region, i.e. in the tender new shoots.
Infestation on Chamaecereus, after treatment the top has sprouted green again©Kaktusmichel.de
The first signs of an infestation on the epidermis are tiny dull spots, which then change to a rusty color. The damage picture widens flatly into a scabbing, which appears almost like a sunburn. These spots are caused by the piercing of the epidermis. Injecting a harmful substance while sucking out the cell sap. The result is loss of chlorophyll. A consequently reduced vigor. Only after a successful treatment intact cells come out of the corking in the middle of the apex again. But the once affected epidermis does not turn green again.
This plant is so badly damaged by spider mites that it should rather be discarded.©CactusMichel.de
The cactus spider mite is spread by infested cacti newly added to the collection. In addition, a population of mites can be brought in through clothing or hands.
Spider mite see arrow©ThornProject.de
But also the other succulents can be infested by these pests.
Infestation of succulents
In other succulents they are found more often on caudex plants of the family Cucurbitaceae and Adenium. The most common pest there is the common spider mite (Tetranychus urticaea), easily recognizable by cobweb-like webs between the petioles and the leaves. It then affects the smooth, soft leaves on which the little animals on the underside of the leaf do their mischief. The damage pattern is usually visible on the leaf veins, also here appears a dot-like yellowing due to chlorophyll deprivation. Subsequently, the leaves wither and are thrown off.
In our latitudes, the common spider mite also occurs outdoors during the summer, often on willows, lime trees, fruit trees and beans, spreading an infestation further via the wind.
Spider mite on succulent caudex plant©Kaktusmichel.en
The spider mite is difficult to see with the naked eye. But with the magnifying glass, we recognize the about 0,2 – 0,6 mm small, yellowish, brown or also greenish animals which run around there busily.
Spider mites love the dryness, they avoid humidity.
On warm dry summer days an adult animal has grown from an egg within a week, which can lay 50-100 eggs and that with up to 9 generations in the year. Everyone can imagine how large a population would be under optimal conditions, a number with 17 zeros.
Natural remedies.
That's why plants that are prone to infestation are better off outdoors in the summer, where damage is apparently undetectable by morning dew alone. But also spraying with water has a healing effect, which can lead to success because of the moisture and the mechanical effect.
With single succulents it helps if the plant is strongly watered packed in a plastic bag and remains in it for 2 days. Due to the high humidity the pests die off. But usually, unfortunately, not only one plant is affected. Then we need other means.
Chemical control.
Who has a strong infestation, will not get around a purposeful treatment. Acaricides (Bi 58, Lizetan AF and others) are suitable for control. But here the used means should be changed more often, in order to prevent a resistance. In these cases I use Spruzit, because of the contained rape oil there is no resistance. Also sulfur preparations, actually against fungi, have proven to be very effective.
Fighting with beneficial insects
Who can create the microclimatic conditions, may also try it with beneficial insects. But he should inform himself before exactly about the living conditions. Otherwise it is a pity for the money. The success is poor.
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