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Dry Mal is a fairly common fungal disease of citrus groves, which may also occur in other plants; It is caused by a tiny fungus, which survives in the ground, and can therefore penetrate a plant through the roots, or it produces spores that are carried by the wind, and which can then enter a host plant through micro-cracks due to external agents, or to the cuts left by pruning. The tiny mushroom propagates inside the wood, and the development is very different depending on whether the plant is struck through the roots or through the wood. In the first case, there is a rapid deterioration of the plant, which dries up and dies within a few months; in the second case, the disease can have a development that lasts for whole years, during which there is the progressive deterioration of individual branches, which later propagates to the entire plant. This different development of the fungus is due to the fact that inside the wood its propagation is slow, and therefore it can hardly reach all branches quickly; instead in the roots it spreads with great rapidity, reaching the whole root system in a few months, and thus causing the death of the plant. Plants affected by badly dry therefore they present sudden losses of foliage, or even entire branches with leaves affected by strong chlorosis, with the rest of the foliage completely healthy. In a short time entire branches tend to dry up completely, starting from the apex; the wood inside has orange or dark zoning, where the fungus has penetrated into the pulp of the wood.
The badly dry It is caused by a fungus, belonging to the genus Phoma; the citrus fruit dry it is usually caused by Phoma tracheiphylla. This fungus of microscopic dimensions, not visible to the naked eye, survives and develops in the soil, or even in the crevices of the bark of plants; as soon as the climatic conditions are favorable, the mushrooms release their spores, called pycnidia, in particular, these tiny fruits (or seeds if we want) tend to spread in the air in the autumn months, when the climate is fresh and humid. Through the ground or carried by the wind these pycnidia tend to be deposited on the branches of plants; where they find a point of entry through the bark they penetrate into the wood, therefore they tend to prefer areas of the trunk exposed due to breaks due to bad weather, or even signs of pruning not covered with mastic. In other cases the spores reach the plants through the moisture of the soil, and are absorbed by the roots, from where they reach the whole plant in a short time. The development of the fungus in the host plant can last for months or years, and an adult tree, struck by the dry sore through a small wound in the wood, can remain alive for many years. On trees affected by dry sore, mold-like formations are often seen on the outer part of the bark; these areas of fungus proliferation are further pycnidia production basins, from which, through the wind, the fungal disease can reach other specimens of the orchard.
The fight against dry illness
The dry sore is quite common in the Mediterranean area, and causes a great deal of damage, especially to the production of citrus fruits; in the areas dedicated to the intensive cultivation of lemons and mandarins the fight against dry sickness is mandatory, as a single sick specimen can act as an incubator for thousands of pycnidia, which over time will be transported by the wind and will attack all the trees in the area .
There is no cure for dryness, and once a branch is hit, all you can do is destroy it; whenever the dry disease attacks a plant, it is fundamental and very important to act quickly, removing all the affected branches, cutting up to 30 cm below the area that shows the symptoms of the disease, until finding healthy wood, and completely free of spots. At each cut it is essential to clean the shears or the saw with alcohol or water and ammonia, to kill any mushrooms present on the blades; the resulting wood of these intervened must be rapidly removed from the orchard and destroyed with fire, or else the fungus will continue to proliferate in it, and the cut branches will act as incubators for new generations of mushrooms. For plants strongly affected by this disease, which may have contracted it through the roots, rapid eradication from the soil is required, with consequent destruction of all the wood by burning.
Prevention of dry illness
As with most fungal diseases, before having to worry about the pathogen inside the plains, it is essential to implement good prevention so that the problem does not occur. The first and most effective prevention consists in planting healthy plants, with healthy rootstocks, belonging to varieties particularly resistant to dryness; in this way we will have a sort of greater protection against the fungus, which will hardly attack our plants.
Other types of caution should be considered at the time of implantation: these mushrooms tend to survive better in a moist and fresh soil: preparing a very well drained soil that does not retain moisture for a long time tends to decrease the cases of infection; in addition to this, the preparation of a turf below the plants also helps to absorb excess moisture, which is used by small grass plants.
In addition to this, if in the area where our plants are found specimens affected by the disease, or we know of cases that have occurred in the vicinity, it is important a good prevention, to be implemented first of all during pruning: all the ramifications cut, they are then protected with pruning putty, in order not to leave large cutting surfaces uncovered; the plants should also be protected from possible atmospheric events that can cause broken branches, such as hail or strong wind; for this purpose windbreak or anti-hail nets are positioned on the plants, in order to avoid micro-fractures of the bark and wood.
In addition to this, following spring or autumn weather events, which may have ruined the wood of our plants, it is advisable to carry out treatments based on cupric products, in order to try to kill the pathogen before it penetrates deeply into the wood.
The lemons in pots
This type of disease can also affect the small lemon plants that we grow in pots, and that we bring to sheltered places in winter; in these cases the disease can be more destructive, because they are small specimens, which can therefore be completely dried up in a short period of time. To prevent our small citrus from being attacked by the important dry disease we learn to cultivate it to the fullest, avoiding the most common errors in cultivation.
First of all let us remember that our lemon will live in pot for a long time, so let's provide it with an excellent soil, very well drained and quite rich; we water only when the ground is dry, and we avoid excessive fertilizations, which can be harmful. In periods characterized by cold climate, we move the plant in allotment, or cover it with straw, or with non-woven fabric, so that it does not undergo sudden changes in temperature. In case of hail or strong wind, we keep the plant sheltered, for example below a canopy, so as to avoid any micro-cracks in the bark.
A good farmer, who owns a large orchard in general, is well aware of how to choose and maintain pruning tools. We mere mortals, on the other hand, often have only a small tree, and our shears we have found for free in a gardening magazine, or we have bought them in a DIY store, in the baskets of the products on offertissima. This is not because we don't care about our plants, but simply because we only have a small specimen of potted kumquats, and we do it once every five years.
Unfortunately many problems related to the cultivation of trees and shrubs in the garden are linked to bad pruning, or performed with unsuitable tools; even if we are not professionals of the green, it would be advisable to get the most suitable tools for practicing pruning; and if we can't afford them, that time of year when we need them, we can try to borrow them from the neighbor.
Shears of all kinds must first of all be very well sharpened; this is because the cut that we are going to practice must be as smooth and clean as possible, without crushing the wood or fraying the bark. With time the crushed or frayed wood dies, and therefore produces on the plant a sort of receptacle for mushrooms of all kinds, which from there can then reach the entire plant. Instead a precise and smooth cut is devoid of parts that will go to rot.
Every time we make a cut, we clean the tool we are using well, before cutting again; in this way we avoid propagating any fungi or bacteria or viruses between the branches. If not we know how to do it, it is enough to take a big clean rag, and wet it with water and ammonia, or with denatured alcohol: after each cut we pass the cloth over the blades to clean them.
When we practice a wood incision, you want to prune it, you want to graft it, let's always remember to cover the cutting surface with pruning mastic; it is generally made of vinyl glue, mixed with dark dye (which acts as a barrier for sunlight), with the addition of a fungicide, so as to prevent anything from entering the wood, just where we cut it. The mastic for pruning is easily available in any nursery or DIY store; it is generally sold in large jars, but it costs very little and has no expiration date, so even if we have to cut a single tiny branch, we can afford to buy it.
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