The defense against Olive moth of second generation - that carpofoga, which goes on olives – is not always justified by levels of harmfulness such as to have to resort to interventions with crop protection products. Taking action against the Moth can prove uneconomical: on the other hand, an economic intervention threshold has never been defined, because it varies according to the load of olives and the variety.
Generally, it is considered necessary a phytosanitary treatment against the carpophagous generation when it exceeds 10% of the infested or at the end of the peak of the flight, before the hardening of the core.
The evaluation must be very timely, because, when the larva has reached the seed, the active substance of a crop protection product is unlikely to be lethal. Because of this, interventions with insecticides executed belatedly prove ineffective.
The eggs of the carpofoga generation are mainly laid on the calyx of small olives, less frequently on the epicarp (skin) of the drupe. After about 6-9 days the larva comes out: usually this penetrates the olive directly from the part of the egg membrane, which is adherent to the epidermis, thus passing from the ovule to the drupe. The larva travels its way towards the inside of the olive along the fibrovascular bundles, which are those channels formed by specialized cells which conduct the lymphatic fluids inside the olive. In this way the larva reaches the stone, which is still tender, and settles there, eroding it from the seed side.
When the larva enters the olive, it is possible that it causes it to fall, causing the green drop. The larvae enter the olives until the stone has become lignified: this occurs approximately after the second ten days of July, a period in which, however, the temperatures easily exceed 30°C and the relative humidity is not high, conditions leading to both the eggs and the larvae perish.
It should also be noted that, in nature, there is a large number of parasitoids of the olive moth.
At this point, if the actions against the Moth could have little economic significance, as far as the intervention thresholds are concerned, they assume, instead, importance in plant protection if we consider it appropriate that the use of an insecticide not only limits the damage from the Moth, but also contains the populations of other seasonal parasites, well present in the olive tree, such as Olive fly, Mealybugs, The Margaronia, Weevils and Cerambycids.
In this case, the phytosanitary treatment, in addition to having the olive moth as a target organism, is important because it reduces the number of adults in Moscow, whose first summer generation generally occurs between the second and third ten days of July. In this case the possible damages of the diptera could be limited and, presumably, having decreased its population, it is possible to control the ovipositions with repellents or antideponents.
The insecticides available to combat the olive moth are:
• Acetamiprid (Epik example with systemic action);
• Spinetoram (example Delegate ™ WDG with trans laminar activity);
• Deltamethrin (example Decis Evo which acts by contact and ingestion before the parasite penetrates the vegetable).
These three insecticides have a broad spectrum of action, they are effective against parasitic insects belonging to various orders, especially with biting and sucking mouthparts.
For the defense with biological techniques you can use the Bacillus Thuringensis, natural pyrethrins o azadirachtin.
Particular attention should be paid to the use of products based on Bacillus thuringiensis, which, acting only by ingestion, does not have the possibility of being ingested by those larvae which penetrate the fruit directly from the part where the egg adheres to the olive . In case of its use, it is recommended to repeat the application; if the water used for the mixture has a pH higher than 8 it is necessary to acidify it before preparing the mixture, for example by adding citric acid about 100g/hl to lower the pH by 1 point; perform the treatment in the evening, because the product is photosensitive; then carry out a uniform and diligent wetting of the foliage.
AIPO Director
Interregional Association
Olive producers
