To insure pollination, it is important to plant more than one cultivar in an area.
Unfortunately, there is no easy answer.
Pecan trees generally have alternate pecan production (on and off years). When trees set a large nut crop, there are not enough nutrients for the nuts to mature and for the tree to store enough plant food.
The nut production will be low the following year. Early defoliation in the fall usually means no nut crop the next year.
Diseases and insects affecting the leaves also contribute to alternate bearing by causing early leaf drop in the fall. To help prevent alternate bearing, use sound cultural practices. These include disease and insect control, adequate use of fertilizer and zinc, and an extra application of fertilizer in late May or June in years when nutset is heavy.
Failure of nuts to fill is caused mainly by insect and disease damage to leaves and an inadequate number of leaves. Drought also causes failure to fill, if it occurs late in the growing season.
In many years lack of pollination causes the greatest loss of nuts. Since pecans are wind-pollinated only, excessive rain during bloom prevents pollination, and the unpollinated nuts fall. Weather conditions in some seasons cause the male and female flowers to mature at different periods, and pollination fails to occur.
Some cultivars shed their pollen before the female flowers are receptive. To insure pollination, it is important to plant more than one cultivar in an area. Insects, such as pecan weevil and hickory shuck- worm, and diseases, such as scab, also can cause premature loss of nuts.