How does the yellow spider affect plants and how is it combated?

The yellow spider is a major grapevine pestThe yellow spider is an important pest of the vine

Image – sercopag.com

There are many pests that can affect plants, so everyone who grows them must keep in mind that, at least once a year, an unwanted insect will be found on the leaves, flowers and/or fruits. Focusing on the species typical of orchards and gardens, one of the most harmful is the yellow spidera mite that feeds on leaf cells.

It is very small, so It is not always easy to see with the naked eye. Moreover, it is interesting to always have a magnifying glass at hand, since it is a very useful tool to see if the plants have any pests.

What is the yellow spider?

Two mites are known by that name: the Tetranychus urticae and Eotetranychus carpini. We are going to talk about both, since although they are very similar, the second is a much more recent plague that also has a preference for the vine. and hornbeams.

Tetranychus urticae

The spider mite is yellow when young.The red spider mite is yellow when young.

Image – Wikimedia / Gilles San Martin

It is a pest that receives several names: two-spot mite (referring to the black spots it has on each of its sides before it completes its development), small yellow spider and, the most used: Red spider, because when it ripens it is that color.

Its biological cycle is as follows:

  • Eggs: the female deposits them on the underside of the leaves. They are tiny, rounded, and translucent, so that it is almost impossible to see them without a magnifying glass.
  • Larval and juvenile phase: they have a yellow body, with a dark spot on their sides, and a whitish head.
  • Adults: turn red and measure about 0,5 mm.

These mites benefit from heat and low environmental humidity, so it is during the summer when they are most active.

Another important fact that you should know is that they have the ability to spin webs. These are very useful for them to go from one leaf to another, even from one plant to another if it is close. Therefore, when you have one with this plague, you also have to treat those around you because it is possible that they are also affected, or that they will be soon if nothing is done.

What are the symptoms or damage it causes?

these mites they feed on the cells of the leaves, and in doing so they leave pale spots that contrast with the green from the same. As a consequence, the plant has problems carrying out photosynthesis normally by losing chlorophyll, which is an essential pigment for this process to be carried out.

If the plague spreads, it invades the entire surface of the leaves, thereby weakening the plant even more. Consequently, other pests may appear, such as aphids, whiteflies, and/or mealybugs.

What plants does it attack?

to almost all. In fact, the difficult thing is to find out which ones it does NOT attack, since only a few (those with toxic sap, such as oleanders for example) are saved. For all these reasons, it does not hurt to inspect the plant well even before buying it, since this way we avoid taking risks.

Eotetranychus carpini

This mite is called the yellow spider or yellow vine spider. Unlike the previous one, it has a much smaller body, with several black dots on its sidesinstead of one on each side. It also has eight legs.

Its biological cycle is as follows:

  • Eggs: the females deposit them on the underside of the leaves. They are sphere-shaped and translucent.
  • Larval and juvenile phase: the yellow spider begins its life having a very light yellowish body.
  • Adults: they measure less than 0,5mm, and are yellow in color.

This is a pest that goes unnoticed in autumn and winter, since the cold slows them down. What’s more, the fertilized females spend these months hidden among the holes in the barkand when the weather improves, the first leaves to be affected are the basal ones, that is, the lower ones.

What are the symptoms or damage it causes?

Plants damaged by the yellow spider have the same symptoms as those that have been attacked by the Tetranychus urticaein other words, will present these problems:

  • Appearance of discolored spots on the leaves
  • These leaves will lose chlorophyll, so they will end up drying out.
  • Your growth will slow down
  • In severe cases, other pests will appear

But there is an important difference with respect to the red spider: the first leaves to be affected will be the lower ones.

What plants does it attack?

It mainly attacks the vines, hornbeams and fruit trees like the peach tree. Still, that doesn’t mean it can’t affect other plants. As I say, always, always, we must review the plants, both those that we already have and those that we want to buy.

How to fight them? Let’s talk about chemical and ecological control

Treat plants with yellow spider

Treat plants with yellow spider

The first thing to keep in mind is that the yellow spider, regardless of whether it is one species or another, is a mite. Mites are insects that multiply very quickly during the warm monthsbut not so much during the rest of the year. Therefore, the best we can do is prevent its appearance, but how?

Well, it’s very simple:

  • If ambient humidity is low, spray plants with rainwater, bottled or lime-free water once a day. But I insist: it is only low. To find out, you must search the Internet for »humidity of X», changing the X for the name of the town where you live, or acquiring a home weather station. And it is that if you spray a plant with water when it is already in a place with high humidity, it will rot.
  • Keep the plant well watered and fertilized. This will help reduce the risk of plague, and should it appear, you will have more strength to survive it.
  • Avoid buying delicate plants. This is difficult, because delicate plants are precious. But it is advisable to acquire resistant species, which can live without problems in our climate.
  • Carry out preventive treatments with natural productsas it is already ready for use, once a month. This minimizes the risk of pests.

But What do we do when we already have the yellow spider swarming freely on the leaves? The first step is to clean them with water and neutral soap. This will NOT eliminate the pest, but it will give the plants a break, and incidentally it will help the miticide that we apply to it to be better absorbed.

And it is that if we want to completely eliminate this plague, we must apply acaricide; not insecticide. Or, a double or triple action that is also acaricide, such as this for example, that it is a ready-to-use spray. You must apply it throughout the plant, and on both sides of the leaves. Follow the instructions for use so that the effectiveness is really good.

The yellow spider can be a pretty serious problem, but we trust that this article will be useful to you, at least, to have it under control.

How does the yellow spider affect plants and how is it combated?

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