First, premature shedding will result from lack of nutritional support of the embryo. On the other hand, if the egg cell is not fertilized, premature shedding will also occur. Research workers do not agree on how soon fertilization occurs after pollination. There is general agreement, however, that pistillate flowers that are not fertilized fall off within 5-6 weeks after they were receptive. June drop may be more conspicuous than the previous drop because nutlets will be larger.
Environmental stresses can increase the nut drop.
Good pollination is a must in pecan orchards. Actual nut development starts with pollination and it can be divided into two distinct phases throughout the growing season. It is difficult to put an exact date on the beginning and ending of these two phases. Because of variation in weather conditions, growing degree hours may give a better estimate. The pecan completes the sizing of the nut during this phase.