The number of recorded insects and allied pests of deciduous fruit (mainly apples, pears, plums, cherries and peaches) in different parts of the world is legion. Many of the most important pests are common to all the main fruit-growing countries of the world, as are some of the important diseases. For the predominant deciduous fruit, apple, average annual world wide crop losses due to pests and diseases are 30% of potential production.
Apples suffer more from pests than other kinds of fruit. The main apple pest is the codling moth which occurs wherever apples are grown. Certain species of mites, including the fruit tree red spider mite, have become serious apple pests over the last 30 years. In the warmer parts of Europe, the San Jose scale ranks as a pest of first importance. Pears, peaches, plums and cherries have pest problems similar to, but usually milder than apples. The mediterranean fruit fly is the most important pest of pears and peaches. Many fungi can also attack deciduous fruit. On apple, two diseases are of outstanding importance, apple scab and powdery mildew, of which the latter is the most serious. On pears, pear scab is a major disease, while powdery mildew is rare. A bacterial disease, fire blight, is a serious problem for apple and pear growers particularly in the USA. The most important disease of peaches is leaf curl, a fungal disease which occurs wherever the crop is grown. The fruit is also susceptible to attack by the brown rot fungi which invade the fruit as it begins to ripen and are sometimes responsible for serious losses.