What technical principles should be followed when thinning flowers and fruit on pear trees?

Thinning flowers and fruit is, on the basis of winter pruning, the regulation of flowers and fruit on trees that still have too many flowers or have set too much fruit; this is a means of achieving a reasonable crop load; its main functions: first, to overcome biennial bearing and stabilize both yield and tree vigor; second, to ensure that the current year's fruit is large and uniform, so that every fruit left on the tree develops into a qualified, high-quality marketable fruit and few culls are produced; third, to form a sufficient number of flower buds for the following year's crop and maintain strong vigor. Trees that are not thinned or that carry an excessive fruit load very easily develop biennial bearing.

The essence of biennial bearing is the problem of fruit and flower buds competing for nutrients. The peak period of fruit enlargement is also the peak period of flower bud differentiation, and fruit has a stronger ability to compete for nutrients than buds; in addition, when there is a lot of fruit, more seeds are formed, and almost all the nutrients are competed away by the fruit, so the buds do not get enough nutrients and cannot form flower buds, which inevitably leads to a light year the following year. Moreover, when too much fruit is left, nutrients are dispersed and in short supply among the fruits, the fruit cannot grow larger, and the proportion of small fruit is bound to be high. Therefore, thinning flowers and fruit and maintaining a reasonable crop load are important measures that affect both the yield and the quality of two years.