Monday, February 6, 2017
WHY ARE MY PECANS NOT FILLED?
WHY ARE MY PECANS NOT FILLED? Why are my Pecan nuts not filled? Is a common question I receive at this time of the year? Pecan nut growth is has two phases. The first phase is nut growth; this determines the size of the nuts. The second phase is nut fill. We are going to discuss the later phase in this article. Around mid-August the nuts will quit growing and start filling. The embryo, (kernel tissue) will reach full size about the third part of September. The nut will continue to fill while conditions permit; the shuck is green and temperature is warm. The storage materials are translocated into the nuts from nearby leaves during the last 6 weeks of filling. A high quality kernel will contain 73% oil, 14% protein, 3-5% water and 1.5% other minerals. The degree to which nuts are filled or how well the kernels are developed at harvest is determined by a number a factors. (1) The size of the crop in relation to the foliage. If there are a lot of nuts but the leaves are small and sparse due to lack of nitrogen or zinc the nuts will not fill. (2)The size of the nuts, if the nuts are large (phase I) it will take more to fill them. (3) Condition of the leaves. In order for the leaves to produce the nutrients to fill the nuts they need to large and in good condition. High aphid or poor tree health will reduce the ability of the leaves to produce nutrients. (4) The size of the preceding crop will affect filling. If the prior crop was large this year crop may be smaller and not as well filled. Also if there are a lot of nuts and no August nut drop the nuts many not fill. (5) Weather condition greatly effect filling. If it is hot and dry it is difficult no matter how much water is put on the ground for the trees to translocate enough water to cool them and produce and transport nutrients. The late rain this year may cause nuts not to fill as well. Also we did not have a very large August nut drop so more nuts stayed on the tree. If the water has any salt in it, which ours does, it make this even more difficult. Rain during the growing season leaches salts and enables all plants to better move water and nutrients. (6) Last but not least is what the pollen source was. All pecans are a result of cross pollination, if the pollen source was from a small nut variety the nuts may not fill as well as if the pollen was from a large nut variety. Example is Burkett pollen on to the Western Schley ovum. The specific effect of unfavorable growing condition on nut development is determined by the time at which the unfavorable condition occurred. Poor growing condition in the early season will result in a smaller number of nuts as well as a smaller nut itself. If they occur in the late season nuts may not be poorly filled. Home owner and producers need to practice cultural management that will provide maximum leaf surface in the spring and early summer. Nitrogen fertilization and irrigation around mid-March before bud break, followed by applications of Zinc will help shoot growth and leaf development. Sufficient moisture, insect control and fertilization will help carbohydrates to be manufactured and stored in late summer increasing quality, and quantity of nuts. There have been a lot of questions about Pecan Weevil and what to treat with. This time of year there is no labeled product that is helpful. The time to control Pecan weevil will be in the mid-August time frame. At this time of the year the Pecan weevil has most likely burrowed into the soil near the tree from which it came. It will be 4 to 6 inches deep. If you have had Pecan Nuts with a small hole in the hard shell about the size of a bb or #2 pencil lead, please call the your Extension Office, in Eddy County that is 575-887-6595. For more information Contact your Local County Extension office. 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.