Main symptoms caused by pests and diseases in fruit trees

Fig. 1 - Aphids
Trees, whose fruits are the most appreciated such as apple, pear, cherry, plum, apricot, nectarine, peach, quince and almond trees, are subject to some common pests and diseases in pome and stone fruits:

Aphids (from several species) - leaves and young shoots, when infested by pink, green, black or brown aphids, show shriveling or small deformations and its development may be reduced or even stunted (Fig. 1);

Red mite (Panonychus ulmi) - the trees that suffer most from this pest are apple, pear, plum and apricot. The most typical symptom can be seen on leaves that are mottled, tan and dry, falling ahead of time. With the help of a magnifying glass, tiny mites can be seen on the leaves;

Codling moth (Cydia pomonella) - the codling moth caterpillars affect mainly apple and pear trees; they dig tunnels to the center of the fruit that can become inedible. It is almost impossible for us to perceive the damage; once the caterpillar leaves the fruit, there are no outward signs of its presence (Fig. 2);
Fig. 2 - Codling moth 
Canker (Nectria galligena) - this disease affects mainly apple and pear trees that, once attacked, show cracks around the base and crimped, deep and discolored spots;

Canker (Pseudomonas morsprunorum) - this bacterial canker affects mainly plum, cherry and peach trees, where we can see small shallow cavities in the branches (often on one side of the branch). The leaves show small round holes (Fig. 3);
Fig. 3 - Canker 

Peach leaf curl (Taphrina deformans) -  it's a disease that affects peach, almond and nectarine trees. One of the typical symptoms are red pustules on the leaves in early summer. Infected leaves turn brown and fall prematurely. Regular leprosy attacks will reduce the vigor of the tree; 

Powdery mildew of apple (Podosphaera leucotricha) - this disease also affects pear trees. Both species show a white powdery dust on the leaves, flowers and branches (Fig. 4);
Fig. 4 - Powdery mildew of apple

Armillaria root rot (Armillaria mellea) -  it affects virtually all fruit trees and the typical symptom is the sudden death of the specimen. By observing the base of the stem bark, it turns out that this comes off easily, revealing a white coating of fungus.

If you were able to identify these symptoms and you don't know how to treat the cause, you can use the OpenPD app, create a post and in the Forum, there will always be somebody willing to share their knowledge with you.
All you have to do is download the free app at

A Horta e o Jardim Biológicos, Pauline Pears e Sue Stickland, Publicações Europa-América, Fevereiro 2006

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