PREVENTION OF HARMFUL CITRUS MINER 27/06/2022

Tangerine oranges, passionfruit oranges, pink tangerines, etc. are citrus trees with a very large planting area, bringing high economic value to farmers. This group of plants has many types of pests and diseases that attack, causing a lot of loss to farmers in terms of product quality and productivity, in which the charm worm is one of the harmful insects that are being concerned.

Charming worm with scientific name: Phyllocnistis citrella Stainton

Belongs to the family: Gracillariidae.

Lepidoptera: Lepidoptera.

The charm worm causes damage almost all year round, especially when the tree has young buds, often causing much harm in July, August, and September.

ECOLOGY CHARACTERISTICS

- This is a small butterfly, about 2mm long, with a wingspan of 4-5mm. Body is pale yellow, slightly silvery. The forewings are willow-shaped, the base of the wings is light gray, the rest of the wings are white, slightly silvery to yellow, with two black longitudinal veins from the base of the wing to the middle of the wing, about 1/3 towards the tip of the wing. Y-shaped oblique veins, wing tips with rather long black feathers. The hindwings are very narrow, often dark gray, with very long, light gray outer feathers.

- Eggs are oval in shape, very small, about 0.2 - 0.3 mm. Newly-laid eggs are transparent, about to hatch are more opaque white than yellow. The incubation period for eggs is 2-7 days.

- Newly-hatched worm about 0.5mm long, light green body, almost transparent, brown head. The worm is large enough to be about 4mm long, greenish yellow in color, the body is no longer transparent. The body is flat, has 13 segments, the two ends are slim, the thoracic and abdominal legs are degenerated, the last vertebrae have a long tubular shape. In the stage of pupal preparation, the worm body is no longer flattened, but turns into a yellow-white tubular shape. Worms are 4 years old, develop in 5-20 days depending on external conditions.

- The pupa is 2 - 3 mm long, the two ends are slender, light yellow at first, then turn yellow brown with a very small spine on the head. Pupae develop in 7-15 days.

LIVING HABITS AND HARMFUL WAYS

- Butterflies are less attracted to light. During the day, butterflies hide in the foliage, at night they fly out and lay eggs, the strongest from 19 to 21 hours. From 12 to 15 hours after pairing, the female butterfly begins to lay eggs.

About 85% of eggs are laid within the first 2 days. Eggs are usually laid on the underside of leaves, averaging 2-3 eggs per leaf or young shoot. Most eggs are concentrated on either side of the main tendon. Butterflies like to lay eggs in orange and mandarin orchards under 4 years old.

- Newly hatched caterpillars bore right under the cuticle and continue to eat into zigzag lines like the lines drawn on talismans, so the worm is called "charm drawing worm". The caterpillar lives inside the turbidity and feeds on the chlorophyll parenchymal cell layer. The cuticle, when newly separated from the parenchyma, is usually shiny, so it is easy to mistake it for the mucus streaks of snails left on the leaf surface when moving.

- Leaves attacked by pests will curl, greatly limiting photosynthesis, young shoots stop growing. In addition to the above effect,  wounds caused by borer on the surface of leaves or shoots will create conditions for Xanthomonas campestris pv. Citri to thrive, causing canker disease in orange trees, eventually the young shoots will be destroyed. The curled, shriveled orange, tangerine or lemon leaves created by the miners are also shelters for many other pests.

PREVENTION MEASURES

- In order to effectively prevent pests, it is necessary to prune branches, pruning at the same time to help produce young buds at the same time, which will control well the miners.

- Clean the garden, collect and destroy, when the plant has buds, it is the right time for the worms to reproduce and need to spray product immediately.

- When young buds are born, they should spray biological pesticides such as Comda Gold 5WG or Comda 250EC, in addition, they must regularly monitor and visit the garden to protect young buds, detect timely detect, and limit insect attacks.

- Gardens that are often under great pressure from miners and diseases can use the Roninda 100SL insecticide, which is an insect growth regulator, with fast contact, systemic and translocation action, and rapid penetration through plant tissues and leaves. affects the nervous system of the larval stage (worm), prevents the exchange of chitin, making the insect unable to complete its life cycle.

- Can mix Roninda 100SL with SK EnSpray 99EC mineral oil and other pesticides and diseases.

- Time of spray:

+ From the time the plant has a young bud until the last leaf in the fully-opened bud , stop spraying, spray 2-3 times 7-10 days apart.

+ Spray when there are abundant butterflies in the garden.