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As an Agriculture Extension Agent for Texas AgriLife Extension Service I have had an opportunity to be involved in just about every aspect of agriculture. From the 5,000 cow dairy to the types of trees to use in a home landscape I have had a chance to learn how the different parts of an agriculture systems work together. Seedless watermelons, drip irrigation, pecan orchard management, fruit crop development, dairy nutrient management, environmental issues confronting agriculture, producer tours, field days, research projects and more have been a part of my life for over 30 years as I lived and breathed agriculture. Since 2004 I have been actively involved in consulting internationally working in Honduras, Guatemala, Egypt, Jordan, Iraq, India, and China. I have worked with missionaries and other groups dedicated to alleviating poverty among third world farmers. I lived in the Middle East in 2007-2008 working on a project for the Borlaug Institute of International Agriculture at Texas A&M University. In this project I was the Chief of Party and Team Leader for a $5.7 Million dollar effort to train Iraqi Extension agents and specialists in all aspects of agriculture.

Sunday, December 21, 2008

Pecan Varieties: Where Do They Come From?

In the preface to Dr. Tommy Thompson’s book entitled “Pecan Cultivars - Past and Present he says there are over 1,000 pecan cultivars (varieties) and he documents 1,012 in his book plus 44 hican cultivars. Of all these cultivars we only truly know the parentage, at least one parent, of 156 cultivars leaving all others to be called natives or seedlings. Needless to say we don’t know a lot about the pecans we so dearly love to eat and grow.
Basically there are three categories of pecans used currently to identify pecan cultivars. The first is Native Cultivars. These trees and their resultant nuts have by chance been planted by flood waters, birds, squirrels, etc. and have grown up and flourished in the environment in which they grew. Natives are by no means always small and hard shelled, in fact we have several named varieties today that started out as just chance seedlings known as natives. Consider the Burkett pecan tree grown throughout Texas and it started as a single tree found in Callahan County. There are literally hundreds of named cultivars that started out as native pecans but over time the person who owned the tree named them and then propagated them because they were good pecans. Most of this naming of natives happened prior to 1920 and since then we have used controlled crosses.
The second category of pecans is Seedlings. These pecans originate from a nut planted by man, where only one or neither parent is known. The planted nut could be from a native or an improved cultivar but when it was planted they really didn’t know what kind of tree or pecan that it would make. For instance the Western variety is one of the largest planted pecan varieties in West Texas and New Mexico and it is a San Saba seedling meaning it was a nut planted from a San Saba pecan tree by E.E. Risien. All we know is that the female parent is a San Saba pecan but we don’t know where the male pollen came from so it is called a seedling. Schley and Mahan are both like this too where only one parent is known. In some cases we don’t even know what one of the parents is but it was planted by man from a favorite native pecan tree and grew up to be good trees such as Stuart or Success.
The last category of pecans is Pedigreed Cultivars. This category is made up of pecans where both parents are known because some form of pollination control was used in producing the seed nut. Basically the female nutlets are covered so that no pollen can get to the pistillate flower cluster and then when it is receptive male pollen from another tree is brought over and fertilizes the nutlet. This cross results in a nut with the genes from two identified cultivars. This nut is planted and grows up into a tree and if the nuts from this tree are of exceptional quality and the tree doesn’t suffer from any problems then the nut may be released with an official name.
This may sounds like an easy process but it is anything but easy. It takes years to know if a cross will be of the quality growers need and expect. For instance many pecan varieties can do extremely well as young trees, such as Cherokee, but as they get older their bad qualities begin to show up such as overbearing, dark kernels and poorly filled nuts. Pecan breeders don’t know this until they grow the trees 20 years or more. Basically the process involves making lots of crosses between the two varieties so that there are lots of nuts produced from the same two parents. These nuts are planted and grown until a fruiting bud or limb can be taken from the small tree and placed on a large tree. This step bypasses the long process of growing a small tree till it produces nuts. These grafted or budded limbs are carefully marked with the number of each tree that they came from and then when it produces nuts they are evaluated for quality and size. Of all the crosses with the same parents there may be only one or two that have good nut quality, but if they do, then those trees that did make the first hurdle are further evaluated for production.
Just imagine how hard it is to know which cultivars to cross, there are trillions of possibilities and even if you identify a cross that seems like it might be good you have to make hundreds of cross of those two parents before you might get one that works. For instance Forkert and Jackson are full siblings, same parents crossed at the same time. Forkert is considered a commercial variety with 49 nuts per pound and grading 62% kernel - excellent. Jackson on the other hand has 38 nuts per pound meaning it is a bigger pecan but it only grades 52% kernel. The Jackson tree is considered a “trash” tree producing “trash” nuts because they’re not filled out. These two trees are from the same parents but totally different and this difference is what makes pecan breeding so very hard and time consuming.

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