The cherry fly (Rhagoletis cerasi Linnaeus, 1758), is one of the main pests of this delicious fruit.
Until relatively recently it hardly affected in the areas of cherries of early maturation . However, thanks to its good adaptability it has already managed to install itself in areas at 500 meters altitude and below.
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Morphological states of the cherry fly
Egg: it is whitish, with elongated-ellipsoid shape and a size of just 0.7×0.2 mm.
Larvae: misnamed cherry worms are whitish and reach between 4 and 6 mm in length.
Pupa: from 4mm of cylindrical size and shape is the way hibernates and the cherry fly spends more time.
Adult: With between 4 and 5 mm in size or their dimensions are similar to those of the olive fly . The wings have tagged spots that alternate dark and transparent colors. On the back you can see a orange semicircular spot.
Biological cycle of Rhagoletis cerasi
At end of April the pupae complete the metamorphosis and the adult fly comes out of the ground. During this period they feed mainly on sugary secretions provided by aphids (aphid).
For about 10-15 days the adult flies mate. The females begin to deposit their eggs when the temperatures are adequate (more than 18ºC). Using the oviscapto (organ used by the fly to perform the chop or put), place an egg under the skin of the cherry. Each female cherry fly has the capacity to put between 50 and 80 eggs.
The fly only puts one egg per cherry, however, if the fly population is high, several flies can chop the same cherry.
Since the beginning of the laying and begin to observe the first worms can take between 2 and 4 weeks.
A few weeks later, after feeding, the worms are buried in the ground forming a pupa and completing a single annual cycle.
Damage caused by the fly
Cherry fly attacks depreciate the value of the fruit. The cherry softens and worsens its flavor, and if the state of the pest is advanced, holes will be visible. In sensitive areas it is necessary to apply treatments against the cherry fly. Otherwise, production losses can be large.
The damage takes between 2 and 4 weeks to be visible so it is necessary to start the control treatments before we can appreciate the activity of the fly.
Control techniques and treatments against the cherry fly
The cultural measures and to a greater extent the treatments with phytosanitary products with insecticides allow to keep under control the cherry fly. Currently, products are being investigated for the biological fight against the plague. focusing on fungi and other pathogens that attack the pupa.
Cultural measures
Do not leave cherries on the tree. Avoid cherries remaining on the ground after harvesting. Use of traps for the fly. To till the land during March-April (before the adults leave).
Chemical treatments with insecticides
The chemical control of the cherry fly should be preventive. Special care must be taken with the plots where it was not possible to harvest cherries during the previous season (damages due to cracking, hail, insufficient price…) Under these conditions a first general treatment is recommended followed by patching applications.
Patch treatments with insecticides to which hydrolysable proteins are added have shown good effectiveness. The bait is applied with a periodicity of less than 7 days on the trunk and opposite branches of the tree. The bait zones must be less than 8 meters apart.
NOTICE: Before applying these products it is important to take into account the security deadlines. One wrong application may mean that we can not harvest the cherries at the optimum time.
The following cherry fly treatments are on the list of products authorized by the ministry as of October 29 2017:
Acetamiprid 0.5%
Trade name Polysect Ultra SL and security term 14 days
Deltametrin 2.5%
We can buy the following commercial products against the cherry fly: Super Delta (3 days), Deltaplan (7 days), Audace (7 days), Decis (7 days), Deltagri (7 days), Scatto (7 days) and Decis Evo (7 days).
Fosmet 50%
Active material marketed under the name Imidan 50WG (14 days)
Lambda Cihalotrin 2.5%
The following products are on sale for the control of the cherry fly: Karate King (7 days), Karate King 2.5 Wg (7 days), Akira (7 days) and Patrol (7 days).
Thiamethoxam 25%
The products authorized for sale are: Actara Y Actara 25 WG, both 14 days of safety term.
Hydrolyzed proteins
The hydrolysed proteins used in the fly patching treatments do not have a safety deadline. NOTICE: We must avoid a direct application on the fruit since they can stain the cherries.
We can find them for sale with the following names: Life Hydrolysed Proteins, Biocebo, Attrack, Nutrel and Flyral.