Wednesday, November 16, 2016
PECAN NUT GROWTH A couple weeks ago we published an article on pecan not being filled and this goes with that information as well. In the past couple of week many homeowners have asked me “Why are my Pecans so small? The tree has never had them this small before.” As we have discussed with nut filling, Pecan nuts form in two stages. The first phase is growth in nut size. It takes about 90 days after pollination for the nut to grow to its full size. This usually occurs between the end of April and middle of August. Toward the end of August the nut has reached its maximum size, so factor which influence size only occur in the first half of the season. The endosperm (nut kernel) is entirely non-cellular until the end of phase I. That is it is mushy at that time of the year, which is why it is called the water phase. Although the ultimate size of the pecans is genetically predetermined, there are some factors that influence the ability of the nut to reach it genetic potential. These are environmental factors such as soil moisture, nutrition status, insects, wind, soil salinity and others. Any one or combination of these factors determines the actual size of the nuts produced in relation to the genetic potential. Tree vigor is very important, in general young trees are more vigorous and bear bigger nuts then do older trees. The position of nuts on the tree is also important. Nuts in the top of the tree are usually larger than those closer to the ground. The size of the crop or total number on nuts on the tree may influence the size. In general the more nuts the smaller they are, the fewer nuts the larger the nut. I have seen cases where tree with a light load of nuts actually produce more pounds of nuts then trees with lots of small nuts. Fertility of the soil and the ability of the tree to translocated water is the most influential factor concerning nut size. Nuts from trees growing on fertile soil and adequate supplied with moisture are usually larger than those from trees on infertile soil or poor moisture. Salt in the soil may make the amount of water available to the tree low even when plenty of water has been applied. When there have been a number of dry years in a row salt accumulates. Rain has a higher leaching ability of salt then most irrigation water. Anything, which reduces the amount of leaf surface, will reduce the size of the nuts. Lack of zinc and nitrogen is common. Aphids will also reduce the ability of the tree to translocated water. In mid-August, the third nut drop usually occurs at this time. The percentage of shed is usually low 5-10%, it concerns a great many people because the nuts are large. Embryo abortion is considered to be the reason for this drop. If the embryo aborts after the shell hardens it will be hollow or what many people call a “pop”. In order to produce large quality nuts the tree must be supplied with adequate amounts of water and nutrients. It must be protected from insects and other factors which reduce the ability of the tree to translocated water. Sometimes environmental factors which are out of our control will reduce the size of the nuts, such as nut load on the trees, hot dry winds, drought, and prolonged excess moisture, compaction which reduces the amount of air in the soil or physical damage to the ovary such as hail. The best you can do is making sure your trees have what they need to be healthy. For more information Contact your Local County Extension office. This and all programs are available to everyone regardless of age, color, disability, gender, national origin, race, religion, or veteran status. 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.