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Plant disease

Plant disease


Description

Plants, like any living thing, can also get sick. Plant diseases are pathological conditions, caused by various factors, which can lead to the modification of the normal physiological conditions of the plant, to an evident suffering on its plant parts, to its withering and, therefore, to death. The disease, in plants, can be caused by pathogens, that is carriers of infections and damage to the plant components of the plant, and by climatic and environmental factors (pollution, incorrect cultivation methods). The main pathogens for plants are parasites (insects, molluscs, other plants and some worms), fungi, viruses and bacteria. All these agents can damage any plant species, from ornamental to agricultural ones.


Disease due to climatic and environmental factors

Climatic and environmental factors are also capable of making plants sick. The former can easily be avoided by growing plants that adapt to the temperatures of the area where the vegetable garden, field or garden is located. Of course, there are unpredictable factors, such as droughts and frosts, which cannot be easily avoided. From these critical factors we can defend ourselves with potted plants, to be moved to places that maintain their ideal temperature, or with greenhouse crops where artificial microclimates are created that do not take into account external conditions. For plants that grow outdoors, both those from organic farming and hedges, lawns, roses, trees and flower beds, climatic and environmental factors can be decisive in favoring the suffering of the plant and its vulnerability to attack. of parasites, bacteria or viruses. Pollution, for example, can change the color of the leaves causing dark spots which, in cultivated vegetables, are an indication of poor quality products.

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Pathogen disease

Plant diseases caused by pathogens are plentiful. Some are named after the infecting agent, others from the appearance that the plant assumes once it is infected. Among the parasites capable of causing plant diseases we remember mites, scale insects, aphids, whiteflies, rose cicada, eels (worms), leaf miner, thrips, bedbugs, the vine oziorinco. , the lily cryo, the winter moth and snails. Bacteria can also cause serious plant diseases. Among the most common bacterial plant diseases we remember the mange of the oleander and the olive tree, the dryness of the geranium and the bacteriosis of the magnolia. Many bacterial infections are caused by Pseudomonas, a typical pathogen of the plant kingdom. Viral plant diseases are often secondary to pest infections, such as aphids. Viruses are, in fact, inoculated through the mouthparts of the parasitic insect, creating a systemic infection that affects the plant parenchyma. Fungal diseases are also harmful to plants, including powdery mildew, smoky mildew, downy mildew, gray mold, rust, white sickness, helminthosporiosis and ascochyta. The disease of the plant can also be caused by other parasitic plants, that is species without roots and without leaves, which, in order to survive, threaten cultivated plants, such as clover, alfalfa and beetroot. Other parasitic species have both leaves and roots, but use them to penetrate the host plant. Victims of parasitic plants with leaves and roots are often legumes. We defend against these diseases with fungicides, pesticides, insecticides or biological systems, such as natural products and predators of infectious agents, but also with correct grafting, pruning, irrigation and fertilization systems.


Cultivation error disease

Plants can also get sick due to cultivation errors, such as too scarce or abundant irrigation and fertilization, incorrect exposure for the physiological needs of the plant (excessive light or shade); grafting and pruning errors. These errors are corrected by learning to know and interpret the signals sent by the plant (curling of the leaves, yellowing, fading or burning). The curling indicates radical damage, too dry soil and excessive heat and can be fought with repotting and changing exposure. Yellowing, on the other hand, indicates an excess of watering and a lack of nitrogen and light and is resolved by enhancing sun exposure, fertilizing more and watering less. The faded leaves are a sign of chlorosis, often caused by too calcareous soils and a fertilization lacking in iron and magnesium, which can be remedied by supplying the plant with the missing mineral substances. The sunburn shows up with red, gray or brown colored leaves. In this case, it is only necessary to reduce the plant's sun exposure.


Plant disease: Plant tumors

Plants can also develop tumors, but unlike humans, these are not primary diseases, but the consequence of bacterial and viral infections in turn caused by attacks of fungi and parasites. Furthermore, plant tumors do not give rise to metastases because the tumor cells of the same have an extracellular spread. Among the secondary tumors of plants we remember the bacterial tumor caused by Agrobacterium tumefaciens which damages the roots and other woody parts of the plant. The plant cancer it attacks both the ornamental ones and the fruit ones. The treatment of this disease is mainly of a preventive nature, ie by practicing cultural measures that help the plant resist the onset of the tumor. To this end, fertilizers rich in phosphorus and potassium can be used. The bacterium responsible for the tumor can also be fought with biological control by resorting to the use of an antagonist bacterium, Agrotacterium radiobacter K84.



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