Plant diseases | What they are, types that exist and how to fight them

Plant diseases are a type of response that plant cells and tissues have to certain environmental factors, or pathogenic microorganisms. They produce a certain change in function, in the form or structure of the plant. If they are not treated in time, these diseases could lead to their partial disability, even death.

Depending on the type of tissue and cell that is affected, the biological function of the plant could be canceled. For example, in the event that the infection occurs in the roots, it could happen that they rot and the plant would not be able to absorb water or nutrients from the soil. In the end he would die.

Some infections attack the leaves, which causes it to interfere with photosynthesis.

It could also affect fruits and flowers, interfering with reproduction.

Most infected plant cells end up dying. However, there are certain exceptions, such as in the case of crown gills , where the cells will divide faster, or even enlarge, which will result in amorphous and abnormal tissues.

Plant diseases are caused by 3 agents: fungi, bacteria and viruses.

It is estimated that 95% of these diseases are caused by fungi, although it is advisable not to neglect this remaining 5% that refers to bacterial or viral infections.

The diseases caused by fungi are usually easy to fight, and it is only necessary to use an appropriate fungicide. However, things change if we have a bacterial or virus infection. In this case there is no product that is considered 100% effective, so it is very important to establish prevention strategies.

Types of plant diseases

To classify the different types of plant diseases with greater success , we have classified them according to these two large groups:

Indoor plant diseases

  • Brotitis:The fungus brotitis (also known as gray mold ), is an agent that will cause brown lesions, also generating a gray mold in the area of ​​buds, leaves and even flowers. It is more lethal in young and tender plants.

The infestation will occur through pruning cuts, wounds or cracks. For example, if the garden has recently had to face hailstorm, it will be crucial to start applying an antibiotic treatment to prevent infection caused by hail injuries.

  • Root rot: Thereare many fungi that cause this problem, but the most common are Fusarium oxysporium, Rhizoctonia solani, Phythium spp and Phytophthora spp.

The first symptom of this plant disease will manifest itself in the leaves; these will turn yellow, reaching a point where they will wilt to end up turning brown. The disease will progress until the roots and stem base rot.

There are chemical treatments against root rot that are applied around the neck of the plant, but are not usually very effective.

  • Powdery Mildew:The powdery mildew is caused by fungi of various genera, how Uncinula spp, Sphaerotheca spp, Erysiphe spp, among many others.. It can occur both in outdoor plants, and in indoor plants. Its identification is not always too simple, since it is presented as a white powder that seems to be just that, dust. However, when we try to shake it we cannot.

In the event that the disease continues, we will discover that the spots will join, becoming larger. All this will cause the attacked parts to dry and fall off.

Some of the alternatives proposed against Oidium are systemic fungicides and sulfur dust.

  • Bold :Bold is one of the most dangerous plant diseases . It is produced from insects such as mealybugs, aphids and whiteflies. When these organisms reach the leaves, they use their beak to nail them in the mimes and extract a liquid from which they will feed. Then they will excrete a substance with a good sugar base, which is what the Negrilla fungus will use to proliferate.

This disease can be identified as a dry black powder. Although it is true that the damage is practically aesthetic, it can also affect the functions of the plant.

The best way to avoid Blackness in plants is to use a system to prevent previous insects from reaching them.

  • Foliar spots: Fungalspecies such as Cercospora spp., Coniothyrium spp or Corynospora spp. Are the ones that produce these characteristic spots. The very affected leaves can not be treated, so we have no choice but to remove them manually. Once they have been removed, it will be a matter of using a systemic fungicide and repeating the treatment approximately every two weeks.
  • AnthracnoseThe Anthracnose is a disease in plants that is identified by the presence of dark lesions and bounded on the leaves and young stems. These areas will dry up, how about a burn.

The leaves affected by this type of diseases of indoor plants must be removed. The application of fungicides only makes sense if the spots have not yet appeared; If so, unfortunately there would not be much we could do to save her.

  • Alternariosis:The first symptom that identifies the presence of this disease in plants is the presence of brown or black spots that, in certain cases, may be surrounded by cylindrical auras. The spots will grow progressively, and at the same time they have the ability to dry the leaves.

It is usually a very common disorder in those plants that do not feed properly. The most logical way to avoid Alternaria is to use preventive treatments.

  • Sclerotinia:This disease directly affects the stem of the plant, causing it to collapse and ending with death. It will not take long to present a characteristic white rot, with an aqueous texture. It is quite common to confuse these plant diseases with a bacterial attack; the difference is that in this case it will not smell bad, unlike what would happen if there were bacteria.

It usually occurs in those leaves, stems and fruits with a size of up to 1.5m above the ground height.

  • Bacteria: Anthurium, Xanthomonas, Pseudomonas… just some of the bacteria that can attack plants. The symptoms that can cause the disease transmitted by these agents are very varied; The most normal is that there is a rot that gives off a bad smell in certain areas.

The most effective way to avoid these attacks is with prevention techniques. The truth is that there are no bactericides that can be considered 100% effective. It also prevents wounds from occurring, as it will be the form of access that bacteria will use to penetrate the organism of the plant.

  • Virus:Virtually any type of plant is capable of suffering the virus attack. The problem with these attacks is that the symptoms are so varied that they are difficult to diagnose. They are easy to confuse with other disorders or pathologies.

The most common symptoms are: presence of malformations and rolled leaves, yellowish pits ( mosaics ), abnormal growth.

It is important that you keep in mind that plant viruses can rarely be cured, so we can only prevent them from occurring, and proliferate by infecting other species.

Outdoor plant diseases

The truth is that many of the diseases of indoor plants also occur in outdoor plants. However, there are exclusive diseases or those that are more common in outdoor diseases, such as the following:

  • Root rot, drowning and stem rot:They are considered as the most harmful diseases for any plant. They usually occur in those soils that have a limited porosity, or that are irrigated in excess. The fungi that cause this problem are usually the Pythium, Phytophthora and Rhizoctonia species , although there are also other fungi that can cause the same problem.

Plants that are attacked by them will have a very varied symptomatology: the most common is that they have lesions at ground level, that they collapse or wilt. In the case of longer plants, these can become infected with pathogens that will cause rot in the highest part of them.

The affected areas usually have a brown color, and the tissue is rotten.

  • Dusty ashtrays:These plant diseases are characterized by a growth of white fungi on the leaves, flowers and stems. The vast majority of fungi can only attack a particular plant, but there are a certain number of fungi that can infect various types of plants.

Fungi survive thanks to the nutrients they obtain through plants, but prevents the latter from being able to absorb them. The development of the disease will be favored by a high relative humidity.

The first thing that should be done in this case is to reduce the humidity in the environment, and then remove those affected leaves and stems before the disease can proliferate.

  • Leaf spots: Leafspots are common in the landscape of any garden. In most cases, the presence of these spots does not represent a serious problem … but it is not always the case. In the event that it was caused by the Entomosporium fungus , the problem will be much more serious than it seems.

The spots produced by this symptom are very varied, and can be from very small, to cover large areas. They usually have a red, purple or even brown tones.

The pathogens are able to survive on remains of leaves or stems; at the time when there is rain or wind, they will disperse throughout the garden, infecting other organisms.

In the same way as in most diseases of garden plants produced by fungi , the situation will be much worse if the humidity is high.

  • Leaf rusts:The rusts leaf is a rare plant disease that occurs only in certain species (eg lilacs, roses, apples or wild). The most common symptom of this disease is the presence of pustules that will appear on the leaves, capable of expanding characteristic yellow-orange spores. You can also find yellow or orange spots on the underside of the leaves.

It is considered as one of the diseases caused by excess water ; the leaves must be kept too wet. With the use of preventive fungicides we can end this disease.

  • Leaf / flower gills :This disease is caused by the fungus Exobasidium spp . It is much more common when spring comes, in cool and wet periods.

Its symptoms are as follows: the tissues of the flowers and leaves will begin to swell, until they become discolored and become fleshy. The guts will end up turning light green-pink. By the time they mature, the gills will turn light white.

The spores, with which the fungus will infect the rest of the plants, will be ready to disperse for the next season.

In addition to an unpleasant color, this plant disease will not cause more serious damage.

  • Blight for Botrytis:If you are looking for pictures of plant diseases , you will realize that this results from the most chaotic. The deep will affect the stems and crowns, can cause gangrene or wilting. In addition, it will cause the discoloration of the leaves and even the death of the plant.

The fungus will travel through water currents and by simply splashing water. They can also be displaced by the help of insects.

The easiest way to detect these diseases of garden or garden plants is by the presence of gray-even spore masses in the walls of plant tissues.

  • Fireblight:The Fire blight is another disease considered the most destructive to plants. The disease – causing microorganisms how this is the bacterium Erwinia amylovora . It usually affects plants that belong to the Rosaceae family, such as apples, pears, fotinia, piracanta, quince, etc.

The twigs that emerge from the central stem will die, giving the appearance of how if they had burned. Fruits and leaves that are attached to the branch will also die. The most normal is that the fungus infects in the months between April-June, which is when the conditions are more humid and warm.

  • Cancrosis:And we end up with this disease that is usually more common in cypress plants that have experienced problems of lack of water for a long time. The fungus that produces Cancrosis or Gangrena is Seiridium unicorne .

The old foliage will start to die (both branches, twigs). Elongated gangrene with a marked reddish color will begin to appear, the bark will turn dark and produce excess resin. Infection can occur anywhere in the tree or plant, at any stage of growth.

How to prevent plant diseases?

Preventive methods

To avoid diseases in indoor or outdoor plants , the best we can do is follow preventive guidelines. If, even so, the infection occurs, we can go to the next section, although we do not ensure the healing of the plant.

  • Quality plants:The first thing you should do is buy quality plants. The roots must be good and not congested. The stems must be vigorous, lozanos … It is important to analyze the plants to determine if they have any type of disease, injury or infection. If so, do not buy them.
  • Climatology:Choose plants based on the climate in which you are going to plant them. Choosing a plant in an inappropriate climate will leave you at the mercy of many diseases that could quickly end your life. For example, imagine that you want to plant the Kentia palm in cold weather. The moment a frost occurs, it will be very weak, and it will be easier for it to succumb to the performance of a pest. You should know that native species are more resistant to pests and diseases than exotic plants.
  • Soil characteristics:You should also know the type of soil you have in the garden. If it is too wet, fungi may appear more easily. If you have too much lime, the dreaded iron chlorosis may appear due to not having adequate iron.
  • Resistant varieties:New varieties of flowers and vegetables that have been modified to be resistant to fungi, viruses, bacteria continuously appear on the market. Although they will not be 100% protected, it is worth opting for them.
  • Plantation:To avoid plant diseases it is important to select a good planting place. Protect them from the extreme conditions of the environment (such as extreme wind, direct sunlight, frost, etc.).
  • Maintenance:If you are not going to have much time to maintain them, then choose a plant that practically stays alone. For example, those that do not need much water to survive.
  • Eradication:If a fungus has killed a plant, infecting its roots and substrate, you cannot plant again in the same place. If you have no other left, make sure you dispose of any remaining infected plant, in addition to changing the substrate.
  • Water only what is necessary:It is just as bad to water too much, as to water too little. An excessive risk encourages the proliferation of fungi ( diseases caused by excess water are the most common), leading to root rot. At the same time, they can get used badly to excess watering. If they have too much water, and they don’t rot for it, they could have a really bad time if there was a dry season.
  • Study water quality:Water quality can be the difference between achieving vigorous plant growth, or dying prematurely. For example, as we have already said, if the water has a lot of lime it is possible that there is a lack of iron. A water with a high pH may be too citrus for certain species.
  • Be carefulof wetting the leaves and flowers with the watering on, as this could encourage the development of diseases. At the same time, as we have seen, there are many fungi that are able to travel from one plant to another simply by splashing (usually diseases of the leaves of the plants ). If a plant is in poor condition, but we will try to save it, we must take every precaution to prevent others from becoming infected.

How to cure plants and diseases?

To cure diseases of garden plants, you will first have to identify the pest or disease that is affected. Next, it will be necessary to assess whether it is worth treating or not.

We have two large group of products to act against these infections:

  • Chemical products:Here we have from insecticides, acaricides, nematicides, fungicides, soil disinfectants, topicidas, rodenticides, etc.
  • Ecological products:Products that respect the environment and the plant. In this group we have, for example, potash soap , mineral oils, rotenone, azadirachtin, pyrethrins, prepared with a base of plants and plant essences, biological insecticides, etc.

We also have pheromones , which are chemicals that keep insects away from plants.

Remember that if the plant has no cure we cannot doubt; it will be crucial to eliminate the affected areas, or directly with it, before the infection can spread to the surrounding plants,

 

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