Almond mite

The almond mite (Phyllocoptes amygdali) is a microscopic pest belonging to the Eriophyidae family. These mites are characterized by a minute, worm-like body that is not visible to the naked eye, requiring microscopic examination for accurate identification.

Adult mites are typically creamy-white or pale yellow. Their elongated bodies are divided into a small cephalothorax and a long, segmented abdomen, which is ringed with tiny protrusions, aiding their movement across plant surfaces.

As members of the Eriophyid family, they possess only two pairs of legs, located at the front of the body. They lack respiratory and circulatory systems, relying on diffusion through their integument, which makes them highly sensitive to humidity levels.

The species is highly host-specific, primarily infesting almond trees. Their lifecycle consists of eggs, two nymphal stages, and adults, with development being heavily influenced by ambient temperature and host plant vigor.

They overwinter as fertilized females, usually seeking refuge in the bark crevices of branches or near the base of dormant buds, surviving cold winters in protected micro-habitats on the tree.

The almond tree is the primary host for Phyllocoptes amygdali. The mites feed on the young, developing tissues, injecting toxic saliva during the feeding process, which disrupts normal plant cell metabolism.

Severe infestations often result in the stunted growth of new shoots and leaves. The damage is particularly critical in young orchards where the formation of the structural canopy is essential for future development.

In addition to vegetative damage, the mite attacks floral buds and developing nuts. This direct impact on the reproductive parts of the tree can lead to significant fruit set reduction and lower harvest yields.

The mites create feeding sites that are prone to colonization by secondary pathogens, including bacteria and fungi, which can exacerbate the decline of the plant’s health during periods of stress.

Prolonged feeding stress leads to early senescence of leaves. Trees lose their photosynthetic capacity earlier than normal, which limits their ability to store carbohydrates required for healthy growth in the following season.

The first signs of infestation are usually subtle changes in leaf morphology. Leaves may appear crinkled, twisted, or exhibit a distorted shape as the mites feed on the meristematic tissues.

Chlorosis or mottled yellowing is a common indicator. This happens because the mites interfere with chloroplast development and function, leading to patches of discolored tissue on the leaf blades.

Dormant buds that are heavily infested may fail to open during the spring or produce very weak, deformed leaf clusters. This symptom is frequently mistaken for nutritional deficiencies or viral infections.

• Leaf curling and deformation (leaf roll).
• Shortened internodes on new shoots.
• Chlorotic or bronzed spots on leaves.
• Premature leaf drop in late summer.

In cases of high population pressure, the overall vigor of the tree drops, making it look sparse and unhealthy, with noticeably shorter annual growth compared to non-infested specimens.

Effective management begins with strict sanitation practices. Pruning out and destroying heavily infested branches during the dormant season is a primary method for reducing the overwintering population.

The application of miticides should be timed carefully with the life cycle of the pest. Early season sprays, just as the buds begin to swell, are generally the most effective way to target mites as they emerge from their wintering sites.

Integrated Pest Management (IPM) encourages the use of predatory mites, such as those from the Phytoseiidae family. Maintaining populations of these natural enemies can provide substantial biological control without chemical inputs.

Cultural practices, such as maintaining optimal irrigation and avoiding excessive nitrogen fertilization, help keep trees robust. Stressed trees, especially those suffering from drought, are much more susceptible to mite explosions.

Regular field scouting using hand lenses is necessary to determine the infestation levels. Economic thresholds should guide spray decisions to avoid unnecessary chemical applications that could harm beneficial predatory populations.