Fruit Drop and Pre-harvest Fruit Drop
Fruit trees usually bear a large number of flowers and only small percentage of which are enough to give a normal yield. For instance a single inflorescence of mango contains as many as 2000 – 5000 flowers and an average of 2 to 3 fruits per inflorescence would provide a good and heavy crop, however the actual percentage of fruit set will be much lesser. When the fruit set is much more than the tree can normally carry to maturity, there will be drop of fruits at various stages of fruit development as an adjustment of tree to its resources. Such drop is natural and beneficial to the trees and it will prevent exhaustion of the resources and breaking of branches by over bearing.
The flower or fruit drop are preceded by the formation of layer or several layers of ceils at the base of petiole pedicle or punend and at the right angles to this axis. These ceils are more or less rectangular in shape and are not cemented together tenaciously and not crossed by fibrous or vascular tissues Consequently breakage or abscission is at that point. The formation of this abscission layer of cells is a natural phenomenon ordinarily taking place as natural maturity is reached. It may be hastened by certain environmental conditions.
The fruit drop usually takes place in definite, waves or at .definite stage and those are
1) Pre setting
2) Post setting
3) Jar drop
4) Pre-harvest drop.
The first drop i.e.,, pre setting occurs shortly after flower opening. Usually flowers with aborted pistil drop off at’ this stage.
Second drop i.e.,post setting occurs a fortnight later than the first, drop. This drops includes unfertilized flowers and some fertilized flowers also drop off at this stage as a result of adjustment in the trees between nutritional factors arid fruit set.
Third drop i.e., June drop occurs when the fruits are marble size due to the formation of abscission layers in the young fruit stalks. This drop usually occurs in most deciduous fruits in the month of June.
These three drops are suppose to be natural one and thinning of fruits hopes the trees to produce remaining fruits with good size.
In addition to the fruit drop like pre setting post setting and June drop rare is a another drop i.e. pre – harvest drop which causes financial loss to grower as it takes place just before the harvest of fruits. At this stage 1/2 developed and 3/4 developed fruits are shed drops to many causes.