What are oomycetes?
Image - Wikimedia / Olivier Ruiz
The oomycetes they are pseudo-fungi (false fungi) that belong to the group of protists Oomycota (or Oomycetes). The species are classified depending on the way they eat. Thus, on the one hand we have saprophytes, which are those that feed on decomposing organic matter, and parasites.
The latter are of particular interest in agriculture and gardening, as they can destroy plants if measures are not taken in time. To detect and prevent these organisms, it is essential to be aware of the Symptoms and treatment of oomycetes in plants.
What are their characteristics?
It is a series of organisms that have a cell wall composed of cellulose. What's more, throughout their alternate life diploid phases, in which cells present two sets of homologous chromosomes in their cell nuclei, with haploid phases in which cells have a single set of chromosomes.
The haploid phase, in these organisms, is the reproduction phase. This is sexual when it produces gametangia; that is, antheridia and oogonia. In them, meiotic division occurs, which will give rise to a diploid oospore that will have thick cell walls. This will be released, and will end up producing hyphae from which the sporangium will develop.
On the other hand, the asexual phase is the one that occurs when motile asexual spores, called zoospores, have a flagellum that is directed forwards, and another towards the rear. These are found in environments where humidity remains high, like the substrate of a plant.
Why are oomycetes not fungi?
For a long time they were believed to be. In fact, they were classified within the Fungi kingdom. But today oomycetes and fungi are known to have few but important differences:
- The cell wall of oomycetes is cellulose. Fungi have it from chitin.
- They are not usually septate organisms. The cells of the fungi, on the other hand, do divide through their internal walls.
- As they grow up, our protagonists have diploid nuclei, and not haploid like mushrooms.
For all these reasons, they are now classified in the class Heterokonta or stramenopiles, which they share with diatoms, for example. For more information on how to detect possible infections, you may find it helpful to consult .
Types of oomycetes
It is estimated that there are about 700 types of oomycetes, among which we distinguish the following:
Mildew
Image - Wikimedia / Rob Hille
El mildew is a very, very common disease in plants, which causes the leaves to be covered with a kind of white dust. Depending on the variety, we find some that seem to have a predilection for a specific type of plant species.
For example, the plasmopara viticola It particularly affects grapevines, which is why it is known as grapevine mildew. To learn about the specific symptoms and how to treat it, visit the section on mildew on roses.
Phythium
Image - Flickr / John Kaminski
The Phythium are a group of oomycetes that affect an even greater number of plants. TO Young plants, such as seedlings, can cause irreversible damage and even death. But when they are adults, and if they are healthy, it is unlikely that they will cause serious problems, beyond some mild symptoms such as a few brown spots on the leaves. To avoid complications, you may want to consult a doctor. tomato diseases caused by excess moisture.
Phytophthora
Image - Wikimedia / Rasbak
It is a genus of oomycetes that attack many, many species of plants. They are quite specific to the species they attack; I mean, that species of Phytophthora They have a preference for a particular type of plant. Knowing the symptoms and treatment of these organisms is key to their effective control.
What are the symptoms and damage they cause?
It will depend a lot on the species of oomycete that attacks the plants. But in general, the symptoms and damages that we will see are the following:
- On the sheets: yellowish or brown spots, whitish powder, premature fall.
- In the trunk: chancres, cracks. Early death of branches.
- In the fruits: brown or blackish spots, rotting of the fruits. Often the stem that connects them to the branches turns blackish, as in the tomato.
How are they treated?
Although they are not fungi, they can be treated with the same products; that is, with fungicides. But for the outcome to be as expected, it is important to identify the disease first and seek a treatment that is designed to treat that specific disease. To achieve this, a proper check-up may also include a review of the health of the casuarina in some specific cases.
El Fosetyl-Al It is a systemic fungicide. The leaves absorb it, and from there it spreads throughout the plant. It is widely used to combat mildew and Phytophthora. The best-known product with this composition is Aliette, from Bayer, especially recommended for browning of conifers. You can buy it .
