Rosemary: Most Important Pests and Diseases

Hello gardeners! If I tell you to think of an aromatic plant , surely rosemary comes to mind quickly . In today’s article, we will focus on identifying what are the most common pests and diseases of this plant  and how to control them.

Rosemary: What is it for?

Its scientific name is Rosmarinus officinalis  and its natural habitat is the Mediterranean region. It develops in any type of soil, preferably dry and somewhat sandy soils. As you know, it is shrubby, woody and its leaves are evergreen (they last on the plant all seasons of the year). Its flowers are purple, pink or white.

This aromatic plant is used in many situations. Among them stands out: rosemary tea , oils, alcohol, soaps, etc. In addition, like many other aromatics and flowers in the garden , it is very useful because it attracts beneficial insects : pollinators (such as bees). The bees are posing in the different flowers depositing the pollen of some in the pistils of others, and making the fertilization that produces the growth of the fruits easier.  

The truth is that it is a plant quite resistant to pests and diseases . The most common are fungal diseases. It is not convenient to water it a lot and excessively fertilized soils can also be harmful.

Rosemary diseases

Rotten roots:  Rhizoctonia spp.

The roots of the rosemary plant can be affected if they receive a lot of irrigation water. Therefore, the soils where we grow them must be permeable. Otherwise, the roots will rot.

It is a fungus that affects the roots and the neck of the plant. The attacked areas show discoloration and later rot. Normally, young plants are those that present this type of disease. This is because they do not yet have well-formed tissues.

Black spots on rosemary leaves : Alternaria spp.

Again we are faced with another fungus. In this case, the symptoms appear on the leaves . If you observe in your rosemary , some black spots like those seen in the photo … the Alternaria is in your garden.

I leave you an article where we talk about how to prevent the appearance of fungi in the garden.

Rosemary pests

This plant is not saved from the main outdoor pests , among which are:

White bugs in rosemary: Cochineal

Although it is not fully appreciated in the image, mealybugs can also appear. I remember that males do not feed on plants and they have wings. On the contrary, the females (which are what we see in our crops) are larvae, they are devoid of wings and are permanently attached to the plants they parasitize.

There are many species of mealybugs , but the most dangerous is the grooved mealybug . It can kill our plants in a short time because it reproduces very fast and they feed by sucking the sap.

We can control them by natural predators and parasitoids of mealybugs such as Criptolaemus montouzieri, Anagyrus pseudococci or Leptomastix algirica. In addition, we can apply chromatic traps or ecological products such as potassium soap or neem oil .

Red spider on rosemary leaves

Although it is known as a spider mite, it is a species of mite. They are usually generalists and mainly affect the vine, horticultural or ornamental crops. They are located on the underside of the leaves and are identified by presenting dark spots on the sides and a large amount of silks.

I leave you a link where we explain how to control the red spider .

Does rosemary repel garden insects?

The smell of rosemary is also not pleasant for some insect pests. We can take that into account for crop associations in the garden. The association of crops is one of the most used techniques in organic farming. It consists of strategically placing nearby plants for their compatibility or benefits one over another. An example is rosemary, which, thanks to its smell, repels some garden pests, such as thrips.

Therefore, a good association of rosemary is with plants attacked by pests that it can repel, for example:

  • With CARROTS. Useful association because it scares away the carrot fly and thrips , typical pests of this crop.
  • With JEWS. The smell of rosemary does not like the plague of the Chrysomela of the bean.

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