Plant diseases

Sore white

The plants of the garden

Just as the garden is one of the places in the house we are most fond of for various reasons, the plants inside it also have their fundamental importance; in fact, since one of the most important tasks / qualities of the garden is to offer us a place of our own where we can relax one step away from home and being immersed in a simple and silent nature, it is clear that all this would be impossible without plants that fill and make our garden alive. Plants, and every other vegetable being, are living beings, which indeed have a certain autonomy due to millions of years of evolution, but it is also true that they need some care without which they would be subject to the natural laws of nature that sometimes they could lead to an early death. Well, among the various treatments there is certainly watering, decanting for growth, but also defending them from disease; yes, it seems absurd but even plants get sick: many diseases affect only the aesthetics of the plant, but others can destroy it and even cause the death of other nearby plants by contagion. Of course, to understand the disease of a plant there are no cough, fever or blood tests, but other signs that we must learn to know.

Sore white


One of the most widespread, powerful and ill-tolerated diseases by man who sees his plants die is the so-called “white sickness”; this disease is so named because it appears externally as a white patina on the leaves, flowers and trunk of the plants that it strikes, almost like a spray of paint on the plant itself. In reality, the scientific name of all this is “powdery mildew”, while in popular cultures there are also other names, such as “fog” or “albugine”. All this is caused by a family of very resistant fungi, which were once classified in the group of “imperfect” Oidium fungi (imperfect because they do not correspond to the classical canons of fungus), and hence the scientific name of the disease. Once the Oidium fungus attacks the plant, it imposes an obligatory parasitism, that is, it almost takes control of the plant which does not know how to get rid of it; in fact the elements of the fungus rest on the surface (classically of the leaves) and penetrate their roots right under the epidermis of the plant, penetrating the internal cells, governing them and taking on all the nutrients, thus slowly bringing them to deterioration.

Effects and solutions

During the phase of the definitive penetration of the disease into the plant, the external effect that occurs is the formation of the white patina previously described on the surface of the attached leaf, a stain that extends slowly. This stain is none other than the mycelium, that is the external body that is common to all fungi, being a fundamental part of them; not only that, the attack described above makes us understand that we are dealing with an ectoparasitism, which however in some species can also be endoparasitism, or attack from within. The effects due to white sicknessthey are not only those that see the appearance of the white mycelium layer on the plant, but they are an initial discoloration of the affected organs, a subsequent necrosis which in the most serious cases can lead to the infection of the whole plant and its death. A classic case is that of grapes: mal bianco attacks the grapes, the surface of which becomes less elastic and therefore tends to break when the grape grows; this causes rifts that are a highway for other diseases, even more serious and specific to the single plant. Solutions to powdery mildew can consist of some species of chemicals but also some natural ones, discovered in the next paragraph.

Sulfur and antioids

Sulfur is a very common natural element which has been found to be very effective in the fight against white sickness; in particular the sulfur has a preventive action, because on the surfaces on which it is sprinkled the mal bianco cannot take root. This is extremely positive because sulfur is practically non-toxic for all mammals (therefore also for humans), but the negative aspect is that it must be sprinkled on every corner of the plant, because if a part of it is left uncovered, that it can be attacked without problems. Another problem is that both powdered and liquid (diluted) sulfur have no effect either below ten degrees centigrade or above thirty degrees centigrade, on the contrary they are toxic for the plant due to the hottest temperatures. It was therefore decided to resort to antioid drugs, or chemical products synthesized in the laboratory that are also able to eradicate the disease when it has already taken root (which sulfur cannot do, having only a preventive action). However, common sense must lead to reducing the use of these synthetic products as much as possible, which are potentially dangerous even for humans if ingested in large quantities and in any case not natural, therefore never one hundred percent safe and always to be avoided as much as possible.

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