Pecan nut development: Pollination and fertilization
The photos above show two important stages of pecan development. The photo on the left was taken May 19th and shows a cluster of recently pollenized pistillate flowers. The photo on the right was taken June 6th and shows the initial nut expansion that follows fertilization and embryo development. Besides the obvious difference in size, notice the position of the 4 leafy bracts just below the blackened stigma. The bracts on pistillate flowers extend outwards from the nutlet while the bracts on the fertilized nut point upwards.
The early stages of nut development are important to recognize because they can be used to time your scouting efforts for early-season pecan pests. Pecan nut casebearer and pecan scab do not attack the pecan crop until nuts become fertilized and begin expanding in size.