Are you an olive-growing enthusiast with a small olive grove? Or are you a large company carrying on family tradition by caring for a vast and centuries-old olive grove so that it can always produce excellent EVO oil?
Regardless of how many olive trees you have, it remains a fact that one of the most feared dangers for these hardy and long-lived trees is the olive fruit fly, which can compromise the qualitative and quantitative results of oil production.
Let’s see together what it is and how to get rid of it!
The olive fruit fly (Bactrocera oleae) represents the main phytosanitary problem in olive growing; pest control must be particularly careful, as any errors can compromise quantitative and qualitative production results. Indeed, oil quality is heavily compromised following significant fly attacks due to the tunnels dug by larvae in the pulp, which cause oil to leak from the vacuoles, resulting in increased free acidity, peroxide value, K232, and the onset of fermentation that induces the occurrence of organoleptic defects in the oil. Furthermore, Bactrocera oleae is one of the few olive pathogens that requires, at least in some areas, constant defense interventions and can therefore represent a limit to the application of organic cultivation methods.
The insect reproduces at the expense of the olive drupes, completing its entire biological cycle (egg-larva-pupa-adult) right inside the olive.
The first generations of this insect are present starting from late spring, coinciding with the phenological phase of the olive fruit set. However, proper attention should be paid starting from the phenological phase of drupe enlargement, which normally occurs from late June to mid-July, depending on the different regions and climatic conditions—a phase in which the olive pulp tends to be receptive to fly stings.
The first thing to do is to monitor this highly dreaded insect.
The monitoring of the pest must take place using the following methods:
Replacement, every four weeks, of the sticky panel and the pheromone dispenser of the traps.
Here you can find a short guide on how to build DIY traps for the olive fruit fly and how to position them in the field!
The collected olive sample must be examined using a stereomicroscope, identifying the drupes that show signs of oviposition. The oviposition sting causes the formation of a triangular-shaped slit 1.0-1.5 mm long, brown in color on the olives (Figures 1 and 2).
Olives showing oviposition stings must be sectioned in search of the different pre-imaginal stages. Determining the infestation involves identifying and counting the pre-imaginal stages and the exit holes of the adults (Figures 3, 4, and 5).
The percentage of active infestation is the only parameter to establish whether the intervention threshold for curative or larvicidal treatments has been exceeded, as provided for by the Regional Integrated Phytopathological Control Plans.
Control involves the application of the following interventions:
Copper-based phytosanitary products are not registered for the control of Bactrocera oleae; the other products are corroborants and enhancers of plant defenses. They are permitted under organic farming regimes.
Now we know what the olive fruit fly is and how to get rid of it. We can take to the field and fight it to protect our olive trees and produce quality oil.
*A maximum of 2 interventions per year is allowed, regardless of the adversity
**Use is permitted from July 1 to October 28, 2020, following a derogation for the use of the active ingredient by the Ministry of Health on July 26, 2020, and a maximum of 2 interventions
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Technician and expert in extra virgin olive oils, registered in the National Register, Campania section. Master oil miller with diploma, obtained from International Extravirgin Agency.
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