Zakat should actually be paid after the winnowing of the grain and the sorting of the fruit.

Nonetheless, it is recommended to assess the amount of all (kinds of) fruit on which zakat is obligated as soon as they have ripened.

The assessor should stop by every tree, and assess the amount of fruit on each tree while the fruit is ripe and then estimate how much it will be after it is dried.

He should differentiate between the different varieties.

He then should say to the owner: "I entrust you to give the recipients of zakat such and such amount of dates (or raisins)".

The owner should guarantee (to give the recipients of zakat) the amount that is obligatory on him.

The owner can then do whatever he likes with all his fruit.

The assessor should he male, Muslim, just, and experienced.

It is valid for the owner himself to be the assessor if he meets the above entioned conditions.

The evidence that assessment is recommended is the hadith narrated by Attab ibn Usaid (G. p. H) that the Prophet (P. B. U. H) said about the zakat of vines: "Vines should be assessed, just as palm trees are assessed, and their zakat is given in raisins, just as zakat on palms is given in dates".

[Al-Tirmithi, Vol. 3, The Book of Zakat, Chapter 17/644]. (pa:326 )

The reason behind assessment is to let the owner know the amount on which zakat is obligated and to safeguard the rights of the poor in zakat.

Further, assessment allows the farmer to take whatever he wishes of his harvest after it has been assessed (without fear of infringing

on the rights of the poor).