Member States shall carry out in 1987, and each fifth year thereafter, in the spring, surveys on plantations of fruit trees existing on their territory for the production of dessert apples and pears, except for purely non-dessert varieties of apples and pears, peaches, apricots, oranges, lemons and small-fruited citrus. The survey on plantations of purely non-dessert varieties of apples and pears shall be optional.