Sexual pheromone diffuser of the species Prays citri to attract males, with a duration of 90 days in normal field conditions...
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|Target pest||Prays del limonero|
|OMDF register number||111/2016|
|ECOLOGICAL||PRODUCT AUTHORISED FOR USE IN ORGANIC FARMING|
Sexual pheromone diffuser of the species Prays citri to attract males, with a duration of 60 days in normal field conditions.
Diffuser of natural rubber in capsule-shape. It is packaged individually in an aluminium sachet with labelled instructions. Once taken out of the sachet, the diffuser does not need any activation operation. Simply place it directly in the trap.
This is an insect that has assumed more importance and is considered at present to be the most damaging pest to lemon trees, as it destroys their floral organs, although it can also damage buds and small fruits.
Since damage occurs during the flowering period, the plants that are most prone to attack are those that have a gradual flowering period such as the lemon tree, in particular the Verna variety which has several consecutive blooms a year. Damage has also been seen in oranges and occasionally in the Clemenules Mandarin which also has a long flowering period.
MORPHOLOGY AND BIOLOGY
The adult is 10 mm in size, grey in colour with several dark spots on the wings which are lined with long fringes. The larvae are whitish or greenish with a brown head.
The adults fly at dusk and at night and lay their eggs mainly on the petals of closed flowers. They may also lay eggs in sepals, buds and small fruits. The larva generally turns into a nymph inside the flower on which it has been feeding and to which it attaches itself with silk threads. It usually spends winter in chrysalis form and it is estimated that it can have up to 3 to 5 generations a year.
On pink petals isolated eggs look like a whitish speck. If many eggs have been laid on the flower buds the damage will be extensive in the flowering period. The caterpillars that hatch from this egg puncture the chorion and directly penetrate the flower in the area between egg and petal.
Source: Professors F. García Marí, J. Costa Comelles and F. Ferragut.
DETECTION AND MONITORING
Use 1 to 2 traps per hectare placed at crop height. Traps may be placed on a support for that purpose.
The traps should be set as soon as new growth begins and the first flower buds appear. Hang the traps from a branch in the sunny part of the tree at a height of 1.5 to 2 metres.
Mostly the males of this species are captured, in order to reduce the mating, so that non-copulated females will have unviable eggs. This reduces the pest population
To carry out mass trapping the number of traps per area should be increased depending on the location and homogeneity of the crops. One trap can control an area of between 500 and 1,000 m². This entails a trap density of 10 to 20 traps per hectare.
An ECONEX POLILLERO, EOSTRAP®, ECONEX TRIANGULAR without sheets, ECONEX DISPOSABLE WHITE TRIANGULAR or ECONEX DISPOSABLE WHITE TRIANGULAR MINI, and a pheromone diffuser ECONEX PRAYS CITRI 2 MG 60 DAYS.
The trap ECONEX WHITE TRIANGULAR without sheets is activated by placing an ECONEX SHEET FOR TRIANGULAR (Code: TA248) at the base of it. The sheet is impregnated with a pressure sensitive adhesive, solvent free, in which insects are trapped. The trap ECONEX DISPOSABLE WHITE TRIANGULAR is coated on its inner face with a layer of contact adhesive, solvent free, for the retention of the insects.
Both traps stand out above all for their simplicity of use, and will be operative until pheromone depletion or saturation of the sheet or adhesive surface. The pheromone diffuser is placed inside the trap on the sheet or adhesive surface.
PERIOD OF USE
To achieve good control of Prays citri, it is advisable to combine the two methods: detection and monitoring and mass trapping.
In spring you can place 1 or 2 traps per hectare to detect the pest and observe the level of their populations. Through established thresholds of tolerance in each area, the control measures are later defined, in this case mass trapping.
The threshold of tolerance for Prays citri is very low and varies according to the area. Generally it is around 7 and 21 captures per trap and per week. Moment in which we recommend to set traps all over the crop for mass trappings.
The most serious damage is caused to the Verna lemon tree during the two main flowering periods, the first in April-May and the second in late summer in September. The June flowering period is not as abundant and therefore the damage is also less.
When the larvae attack the flowers, they feed on the anthers and the pistil inside. They then move on to other flowers and link the entire damaged area together with silk threads. These form masses in the interior in which there are a lot of dry petals and dark-coloured excrement. The damage can be confused with that of Cacoecia but this pest mainly attacks early fruit and not flowers and it does not produce sawdust and excrement.
Once on the leaves the larvae can feed off the epidermis. They bore a gallery along the shoot in leaf buds making rubbery excretions. When they attack recently set fruit they usually bore a gallery in the style and end up eating the entire fruit.
Damage to developing fruit can be seen as blemishes on the surface caused by the larvae eating the peel. The chorion of the egg can be found in the centre of these blemishes.
Occasionally the larvae can also damage the grafts of all types of citrus fruit trees as they penetrate beneath the shield and feed on the cambium so the graft dries out. Once the damage is complete the larva moves down to the soil to pupate. The larvae may also pupate near the damaged area. Similar damage to the grafts can be produced by other pyralids such as Ephestia sp. or Cryptoblabes.
FACTORS THAT INFLUENCE THE NUMBER OF TRAPS REQUIRED
Pest population, adjoining crops, level of control required, etc.
An important factor is crop size. More traps are needed in small and irregular sized crops than in uniform plots with a larger surface area. Another important factor is the distance from other plots that have the same pest. In such cases plot boundaries should be consolidated, so a trap density of up to 20 traps per hectare may be needed. More traps may be needed in the case of mass trappings
If technicians or farmers use the traps and pheromones as described here and when the first generation of adults emerge, then the effectiveness of this control system is very good, as proved by data from many organic farms. Where large crop areas are covered more than 95% of the pest is often controlled.
A factor limiting this system is where there are small farms in many places with neighbouring plots that have a high level of pest infestation. Apart from some important basic rules in controlling Prays citri effectively each farmer/technician should find his/her own system of achieving this and he/she may experiment with the system even establishing his/her own tolerance thresholds.
STORAGE OF THE DIFFUSERS
The diffusers must be kept in their original container and in a refrigerator at 4oC, or in the freezer at -18oC, in which case they will remain valid for 2 and 4 years respectively.