Woolly aphid of the apple tree

Woolly aphid of the apple tree

Woolly aphid of the apple tree

The woolly apple aphid is a pest that is very difficult to eradicate. Erisoma lanigerum is an insect with a variable length between 1.5 and 2.5 millimeters, with a red-purple color. This insect is able to secrete a fluid with a waxy consistency that could completely cover the branches, roots and every woody part of the plant. The aphid is able to overwinter (only the female specimens) on the plant, resuming its activity in spring with the generation of new individuals. The infestation would spread through individuals with wings that appear in the summer. The adult specimen is particularly sensitive to cold, while in the larval stage they can resist even temperatures close to -25. Activation usually takes place between the months of April and May.

Wool aphid of the apple tree">Damage

The damage that is caused by the woolly aphid of the apple tree consists mainly in the appearance on the branches and on the woody parts of the plant of tumors or knots that are caused by a hypertrophy or hyperplasia affecting the cells. In fact, the salivary juices of the aphids are able to stimulate the deformation of the structure of entire parts of the plant. Plants infested with woolly mites could also become much more receptive to other diseases, causing in some cases the entry of fungi or other parasitic insects. Woolly mites are able to settle in pre-existing wounds on the plant, caused by other parasites such as, for example, from woodworms or on pruning scars. A prolonged attack could lead to significant damage to plants and loss of fruit production.

Fight against infestation

The fight against woolly apple aphid could include both biological and chemical control. The aphid could be controlled by the Hymenoptera Aphelius mali which is able to effectively counteract the infestation. The parasite is able to overwinter inside the aphid larvae, feeding on them and leaving them completely emptied at the moment of flickering. To safeguard parasitic insects, it would be advisable to adequately control winter interventions with polysulphides and yellow oils which are particularly toxic for the aphelius. In case of extensive infestation it would be advisable to treat the plants with specific aficidi trying to safeguard the Chrysopids, the Coccinellidae and the Hoverflies. This intervention should be carried out both before and after the flowering of the plants.

Care of infested plants

The use of oils has proved to be the best method to combat infestations by this type of insect that can experience serious damage to apple plants. The oils should be spread on plants during the summer, but in the presence of heavy infestations and with the risk of losing crops. To avoid that the plants suffer infestations it would be advisable to avoid extensive and invasive pruning interventions. In the case of infested branches it would be advisable to eliminate them before the aphids attack the entire plant. Proper fertilization of the soil would be able to provide adequate nutrients to the plants in order to make them more vigorous and more resistant to attacks by aphids. In case of grafts it would be advisable to use rootstocks that are resistant to attack by the wool aphid.

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