Durian trees are perennials and they use all the food reserves of the trunk, branches and twigs for fruit production. After each fruit bearing season, all these food reserves are used up and need to be replaced. Durian trees take up nutrients year after year from the soil around them. Fertilizers are needed to maintain the health and productivity of the trees. More nutrients are needed as the trees grow older and bigger. Weaker/older trees require more nutrients to help them recover. 

Calcium and magnesium deficiency in durian makes yellowing of older leaf tips followed by necrosis and leaf drop resulting in drop of flowers and smaller size of Durians.

By correcting soil pH , the fertilizer requirement for durian will go down and efficiency of fertilizer usage improves. The supply of adequate quantity of Calcium and Magnesium nutrients will help in producing better quality durians in good numbers.