We are searching data for your request:
Upon completion, a link will appear to access the found materials.
Psylla is one of the most frequent pests of the pear tree, and its presence on the plant causes so much honeydew as to favor the establishment of smokiness, with the result that many plant organs are soiled.
The danger of the pear psylla was greater in the 70s and 80s, when there was a massive use of non-selective chemicals, causing the loss of antagonistic insects in cultivated environments.
Populations of this parasite had differentiated resistant to insecticide molecules which could proliferate freely. Subsequently, agriculture has increasingly taken the path of integrated pest management or in any case the limitation or banning of many plant protection products, also due to the constraints imposed by the European Union.
Controlling the pear psilla is now possible with less impacting methods, even in organic fruit growing. The important is understand immediately when the pear trees are affected by the insect and intervene in time, possibly having already thought about prevention upstream through many precautions. So let's learn about the insect and understand how to curb its attacks.
Characteristics of the insect
The psylla (Psylla or Cacopsylla pyri) is one of the key phytophages of the pear tree, it is an insect of the order of rincoti.
The adult it is small, just 2.5-3 mm long, of an ocher, hazelnut or brown color depending on the age (the wintering forms are darker). The wings are transparent and positioned on the sloping roof body.
The nymphs they are flattened, have a yellow-orange color that tends to become progressively darker, until becoming blackish and have two typical lateral expansions. These juvenile stages are covered with thick honeydew which has a protective purpose.
The eggs they are yellow-orange, elongated and with a sort of tip, while at the other end there is a sort of tail.
The psylla overwinters as an adult finding several shelters in the orchard, then as early as February, when temperatures exceed 10 ° C, the insects come out and lay their eggs at the base of the buds. Up to 5 generations of pear psylla occur in one year.
Damage to the psylla of the pear tree
The psylla, especially in its youthful forms, it easily attacks the pear shoots, the tender leaves, the still young branches, rarely even the small fruits.
On all these organs we can see the abundant honeydew which covers individuals with psylla and in severe cases there is also an abundant loss of leaves.
The damage is both direct and indirect.
- Direct damage: is due to nutrition bites which cause deformation and vegetative stops, with small necrosis points on leaves and shoots.
- Indirect damage: is caused by the honeydew which, covering the plant tissues, causes asphyxiation and sunburn due to the fact that this substance sometimes has a slow effect on the leaves and thus concentrates the sun's rays. The honeydew also causes a loss of quality on the fruits, which if they are intended for sale, are depreciated; it also favors the establishment of saprophytic fungi such as fumaggini, which hinder chlorophyll photosynthesis. Finally, the psylla is a potential vector of the phytoplasma responsible for the death of the pear tree, a plant disease that can be fatal to plants.
To prevent the attacks of pear psylla from compromising the health of the plant and also the harvest, some important measures must be implemented to contain the attacks. Among these we mention:
- Careful fertilizations, not excessive, as the psylla is attracted to the nitrogen-rich sap.
- Light pruning, which do not stimulate the vegetative vigor too much.
- Adoption of all the techniques aimed at promoting biodiversity: total or partial grassing, presence of hedges, bushes and spontaneous blooms, in short, everything that favors the presence of predatory insects and parasites of the psylla.
Defense against the psylla of the pear tree
In organic farming we can fight the pear psylla both with insecticides and by using antagonistic insects in the fight.
Biological insecticide treatments
Marseille soap, or soft potassium soap for agricultural use, are effective as insecticides with low environmental impact, used in doses of 10-20 grams / liter of water. But it is very important to remember to carry out the treatment in the cool hours of the day so as not to cause burns to plant tissues.
Another product to use against psylla is the quassio wood (Quassia amara), which is obtained from a tropical plant whose wood and bark contain quassin, coumarins and other alkaloids. These substances are used for the preparation of an odorless natural insecticide, but with a strongly bitter taste. To filli a decoction it is necessary to macerate 20-30 grams of quassio in a liter of water for a few days, then when the maceration is finished, it is put to boil for 40-60 minutes. After cooling and filtration, the decoction is diluted with water until it reaches 10 liters and the treatment can be carried out, also in this case in the cool hours of the day.
The real biological fight consists in the launch of antagonists, in this case L'Anthocoris nemoralis, insect of the order of rincoti, which is launched between March and April in the number of 1000-2000 individuals per hectare.
The strong limit of this method for private agriculture is that it does not work on small surfaces, because there is too much dispersion of insects in the external environment. So that the results can be appreciated an orchard of at least one hectare is needed, therefore in the cultivation of professional organic pear trees it is certainly a recommended route.