Tuesday, February 9, 2016

Making pecan breeding plot selections

     To many pecan growers, thinning a pecan orchard is the hardest job they will ever have to accomplish. Cutting down trees that required so many years of work to grow seems heartbreaking. But over the weekend, I started thinning trees in our pecan breeding plot (photo above). This is more than just a simple tree thinning operation. I was making tree by tree decisions of which trees were worth saving and which would be eliminated from the breeding project.

    Many trees in the breeding plot have now produced nuts for three years giving us a good idea about nut size and percent kernel for each tree. As you would expect, the nuts produced by a field of seedling trees varies widely. The photo above shows nuts produced by three trees in our breeding plot. The nut at the far left weighed 8.17g and yielded 58.61% kernel. This is one tree I definitely needed to save. The football shaped nut in the center produced a very attractive but small kernel. However, at only 4.54g and 47.29% kernel, I choose to cut down this tree. At the far right, this small 4.99g nut had a thin shell (53.67% kernel) but the nut was way to small to remain in the trial.

    Not all tree removal decisions were based solely on nut size and percent kernel. I choose to remove trees that produced kernels with serious defects and trees that exhibited severe susceptibility to pecan scab. The photo above illustrates one kind of kernel defect that warrants tree removal. The nut on the right is marked with very unattractive dark brown mottles. Compared to the bright straw-colored kernel at left, it is easy to see which nut would be attractive to consumers (left nut) and which tree needed to be removed (right nut).