Organic struggle with the Cotonello of the olive tree
The olive cotonello (Euphyllura olivina (Costa)) is an insect of the parasitic family of the olive tree, which in case of infestation can cause serious damage. The damage is due to both the direct activity of food bites, which weaken the plants, with negative effects on production yields, due to the indirect effect of waxy secretions that cause the abortion of many flowers.
Specifically, the damage occurs on sprouts, inflorescences, fruit and is determined by both trophic bites caused by adults and juvenile forms and by asphyxia caused by the infesting colonies, protected by waxy secretions and honeydew (to which is added later the formation of fumigations that further aggravate the damage). In particular, the attack on flowers causes flowered abortion and dripping, while on the fruit it causes cascola. In addition the infested shoots show a stunted development and sometimes they can completely dry out. Unfortunately, the major attacks occur at the time of flowering and setting (where the damage is more substantial).
In this sheet we will see the necessary interventions of biological control to the Cotonello of the olive tree and the most appropriate techniques.
The Cotonello of the olive tree overcomes the winter as an adult refugee on the lower part of the twigs, their armpit, buds and leaf petioles and at the end of winter, during sunny days, resumes the trophic activity and immediately after females lay about a hundred eggs, with a cadence of 4-14 per day, both on the lower page of the leaves in formation, and on the axillary buds, on the shoots and on the leaf petioles.
The infestations become greater especially on olive trees with very dense foliage where they are created, due to the insufficient penetration of light and air, favorable micro-environmental conditions to the insect.
For this reason the olive trees must be pruned, in a balanced way and possibly every year, so as to favor the aeration and penetration of light into the foliage (which also contributes to soil moisture conditions favorable to the insect).
Another fundamental and often neglected aspect is linked to the fertilization system adopted. The use of nitrogen fertilizers from nitrates (and to a lesser extent from ammonia salts) causes excessive vegetative growth of the plants and a greater nutritional approval of the insect. For this reason the fertilizations should be only organic in nature (well-mature manure) and integrated by grassing and green manure with legumes.
The nesting technique, combined with the possibility of rows of plants of other species (such as for example the nasturtium (Tropaeolum majus L., 1753) or the tansy (Tanacetum vulgare (L., 1753)), to name a few) becomes fundamental for the creation of the agroecological biodiversity necessary for the growth of some of its natural entomophagi.
In fact, in fact the Cotonello of the olive tree is effectively controlled by some entomophagi, among which we mention: Chrysopid Neuroptera, Ditteri Sirfidi larvae, Rincoti Antocoridi (including Anthocoris femorali) Encyrtus euphyllurae along with other parasitoid Hymenoptera.
In general, the specialization and monoculture of the olive grove, the too dense sixths, the net soil from herbaceous vegetation create conditions of difficult control of this insect.