Li et al. (pp. 137-143) show that carbohydrate accumulates in leaves and shoots above a stem girdle in citrus trees during their fruitless, �off� year but not during their fruiting �on� year. Girdling is also shown to decrease markedly carbohydrate concentrations in roots. Expression of starch biosynthesis-related genes is high in starch-accumulating organs and low in roots with declining starch concentrations.