Apple blossom weevil

The apple blossom weevil (Anthonomus pomorum) belongs to the Curculionidae family. The adult beetle is about 4-5 mm long, brownish-grey with a characteristic light V-shaped mark on its elytra.

The larvae are legless, C-shaped, creamy-white with a brown head capsule. They develop entirely inside the flower buds of apple trees, where they undergo their entire larval stage.

Adult weevils overwinter in crevices of tree bark, under fallen leaves, or in debris near the base of the trees. They become active when temperatures rise in early spring.

Their life cycle is closely synchronized with the phenology of the apple tree, ensuring that eggs are laid exactly when buds are becoming available for the offspring.

Recognizing the adult beetles is difficult due to their camouflage, but their presence is confirmed by specific damage patterns and the appearance of the "capped" buds.

The primary host for this pest is the domestic apple tree (Malus domestica). The weevil specifically targets the reproductive parts of the tree during the early spring growth.

It is important to note that crops such as forage beet, cabbage, industrial hemp, sweet pepper, winter barley, common hop, or alfalfa are not preferred hosts for this specific species.

The main damage is caused by the larvae feeding on the inner parts of the flower bud, specifically the stamens and pistils, preventing the flower from opening properly.

In cases of high infestation, the pest can cause significant yield losses by destroying the majority of potential apple blossoms before they can be pollinated.

Adult feeding also causes damage by piercing the buds with their rostrum, leading to sap leakage and physiological weakening of the fruit-bearing shoots.

The seasonal cycle begins in early spring when temperatures reach approximately 8-10°C, prompting adults to move from their overwintering sites into the tree canopy.

Mating and oviposition occur during the "green cluster" stage of the apple tree. The female lays a single egg inside each bud, sealing the puncture site with excrement.

Larval development takes about 2 to 3 weeks. The larvae consume the inner tissues of the bud, which then fails to develop into a blossom.

Pupation takes place inside the withered bud, which turns brown and remains attached to the twig, creating the familiar "capped blossom" appearance.

New adults emerge shortly after the flowering period ends and remain active for a short time before entering a period of summer inactivity and eventually hibernating.

The first sign of infestation is "weeping buds," where small droplets of sap appear on the buds due to the feeding punctures made by adult weevils.

The most distinctive symptom is the presence of "capped blossoms"—buds that turn brown and shrivel without opening, remaining on the branch like a cap.

If you split one of these brown, shriveled buds, you will likely find the white larva or the pupa of the weevil inside, which is a definitive indicator of the pest.

During the early morning, adults can be detected by shaking branches over a white sheet, causing the beetles to fall and exhibit thanatosis (playing dead).

A widespread occurrence of these capped blossoms after the blooming season indicates a high population density that necessitates intervention for the following season.

Cultural control practices include scraping off old, loose bark from the trunks to remove overwintering sites and clearing debris from the orchard floor during autumn.

Mechanical control involves shaking trees in the early morning while beetles are sluggish and collecting them on sheets to be disposed of away from the orchard.

Applying sticky glue bands to the trunks in early spring can trap ascending adults, effectively reducing the number of weevils reaching the flowering canopy.

Chemical control should be timed precisely to the "green cluster" stage of development, using approved insecticides before the larvae are protected inside the buds.

Integrated pest management (IPM) encourages the preservation of natural predators and the use of targeted applications to maintain a healthy balance in the orchard ecosystem.