Falling Pecans

PECANS ARE FALLING. Pecan nuts grow in two phases. The first phase includes pollination, nut enlargement, and water stages. This usually occurs between the dates of May 1 to August 15. Phase II is kernel filling and shell hardening. This usually occurs from August 15 to November 1. Close to the date when the first phase of nut development is complete, the third nut drop, called the August drop occurs. This usually occurs from August to mid September. It causes greater concern to pecan growers and homeowners because of the large size of the nuts at this time. Although the percentage shed is generally low, 8 to 10 percent. Some trees in the area this year have had very high percent shed however. Embryo abortion is considered to the reason for this late drop. By the time August drop takes place, the embryo has attained full size, the ovary has about completed its enlargement and the pecans will soon begin to harden. Premature shedding will occur when something affects the embryo. If the embryo aborts after the shell hardens, the nut usually matures, but will be hollow or what is commonly called a pop. Although the causal factors for embryo abortion are not known, some researchers consider the following situations, to be related to embryo abortion: • A severe drought or later stress. This is more likely to occur in poor soils and it frequently takes place during the water stage. • A prolonged period of excess moisture. Lack of air in the soil impairs the root system capacity to absorb water and nutrients required by the pecan tree. • Hot, dry winds can increase water loss by increasing the pecan tree moisture requirements due to high transpiration rates. • Insects (Shuck-worm, southern green stinkbug, pecan weevil). Puncturing of the ovary wall, the future nutshell will cause nuts to fall in 3 or 4 days. • Any physical damages that can disturb the ovary wall (shell) of pecans. In general this has been a stressful year due to the changes of temperature cool then hot, and water requirements of the trees. Rainwater not only helps supply water to the trees it also has a higher leaching capacity for leaching salts from around the roots. Salt can cause a physiological drought in the trees, which cause embryo abortion. With the rains some people did not keep up with the water requirement of the trees. Look at a sampling of the fallen nuts and check for insect damage to the shuck or the shell. Pecan Weevil has increased its territory in Texas so if you find a whole in the nut and a grub inside bring that to the Extension Office. If you are having a high August nut drop, all you can do is water correctly, not to much, and not to little and take care of the crop you have left. Subscribe to Eddy County Ag news at: http://nmsueddyag.blogspot.com/ Eddy County Extension Service, New Mexico State University is an equal opportunity/affirmative action employer and educator. All programs are available to everyone regardless of race, color, religion, sex, age, handicap, or national origin. New Mexico State University, U.S. Department of Agriculture, and the Eddy County Government Cooperating.