<P> Biennial bearing (or alternate) bearing is a term used in pomology to refer to trees that have an irregular crop load from year to year . In the "on" year too much fruit is set, leading to small fruit size . Excess weight in the main branches can be too much for their mechanical resistance, causing them to break . Another major consequence is that flower induction will be lower, and the subsequent year will be "off" year (too little fruit). </P> <P> The behavior could be due to plant hormones, particularly gibberellins produced in excess in the "on" years in the embryos of the young fruit . It could also be caused by depletion of carbohydrate reserves in the tree . </P> <P> Biennial bearing is more common in certain fruit crops like mango, apple, pear, apricot and avocado, and is almost nonexistent in grapes . </P> <P> This disorder can be reduced by thinning of flowers and young fruit . </P>

Describe biennial bearing and its causes in mangoes