il cotonello dell’olivo (Euphyllura olivine) is a very common parasite in Italian regions where olive growing is practiced. We find it more frequently in coastal areas and in areas characterized by mild springs associated with high relative humidity. Heavy infestations of olive cotonello can cause damage especially during the flowering period, affecting the olive production of the year. Fortunately, this parasite is controlled by numerous antagonistic insects, which limit the incidence of damage. However, it is important to know how to recognize it and to know how to evaluate the effects of its presence, intervening when necessary with products allowed in organic olive growing.
In this article we see the description of this insect, its biological cycle, the damage it causes to olive trees and the appropriate bio defense strategies.
Description of the olive cotonello
The olive cotonello is an insect belonging to the order of Rincotifamilja ta ' Psylidsġeneru Euphylluraspeċi E. olivine. Here are the morphological characteristics to recognize it.
Cotonello of the adult olive tree
- Length of almost 3 mm;
- Stocky body, initially light green in color, which over time turns to brownish;
- Head of yellowish color;
- Obvious red eyes;
- Wings that in rest position enclose the “roof” body.
Olive cotonello eggs>
- Cylindrical shape;
- As soon as they are laid, they are yellow in color, turning to yellow-orange.
Olive cotonello nymphs
- Tul 1 mm;
- Light yellow color;
- Bright red eyes;
- In the posterior part of the abdomen there are the ceripar glands, capable of secreting cottony flakes in abundance, hence the vulgar name of the species.
Iċ-ċiklu tal-ħajja tal-insett
The olive cotonello overwinters as an adult in the vegetation of the tree. In particular, at the base of small twigs, under the leaves and in the axillary buds. It resumes its cycle in spring, when it begins to lay eggs (between 150 and 200). L’ovpożizzjoni it occurs in the flower buds and in the lower page of the leaves placed on the terminal ramifications. After about 2 weeks, the ninfi, which feed on the plant organs that they find when the eggs hatch. The peculiarity of this parasite is the abundant production of wax flakes, rather evident, used by the nymphs to protect themselves. After this first phase, the nymphs attach themselves under the leaves to move on to adult stage. The entire life cycle of the cotonello can have a variable duration from 25 to 50 days. It turns 3-4 generations a year, but it is the first spring generation that can cause the greatest damage to trees.
Damage of the cotonello to the olive tree
The cotonello of the olive tree, both at the nymph and adult stage, feeds on the sap of the tree, through trophic nutrition punctures. These are practiced on the floral buttons, causing flower abortion u / jew sterilitàtherefore failed sett tal-frott.
The second generation of cotonello can cause damage even to small olives just attached, causing them to falls early. The wax that the cotonello secretes, moreover, gives rise to abundant honeydew productionfrom which a later one can derive fumaggine. This is due, in the case of the olive tree, to the establishment of the ectoparasitic fungus Capnodium oleaginum. Smoke is that annoying blackish patina that smears the leaves, causing asphyxiation and a general deterioration of the vegetation. The damage can be high in case of heavy infestations and depends on the climatic trend of the spring season and on the vegetative state of the tree.
The proliferation of the olive cotonello
The proliferation of the olive cotonello is strongly conditioned by the climate of the spring season. A rainy spring hinders the development of the parasite, as the waxy protection is washed away by precipitation. As the layer of wax disappears, the insect is exposed to other atmospheric agents (sun, wind, drops in temperature), which actually limit the severity of the damage. High summer temperatures are also a negative factor for this insect. As a result of excessive heat, in fact, there will be weaker and fewer generations.
Antagonistic insects
Fortunately, there are many in nature insetti ta’ benefiċċju which naturally control the populations of olive cotonello. The antagonists in particular are:
- parasitoid hymenoptera: Psyllaephagus euphyllurae, Trecnies spp, Alloxysta eleaphila;
- diptera hoverflies: Syrphus auricollis u S. flavomarginatus;
- the hemipterous rincoti: Antochoris nemoralis u Deraecoris spp.
The grassing
In an environment characterized by a high degree of biodiversity, the presence of olive cotonello is kept under control by antagonistic insects. The management of the olive grove with theħaxix it certainly favors biodiversity and therefore the control of the presence of cotonello.
How to eliminate the cotonello of the olive tree
It is quite unusual that specific action must be taken against the infestations of olive cotonello. It is also true, however, that lately we are witnessing greater pressure from this parasite, especially in the southern regions.
It must be said that usually the interventions put in place for the fly taż-żebbuġ they are also effective against cotonello, for which control is indirect. The specific intervention is necessary if the infestation gives rise to an excessive production of fumaggine. In such a case, an abundant washing of the vegetation with sapun tal-potassju artab solves all problems. Recall that potassium soft soap is a product allowed in organic farming. Obviously it is a specific formulation for agriculture that must be of good quality. If you are looking for it, you can find a good product below.
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