Monday, October 8, 2012

Pecan cultivar testing takes time

Kanza pecans
     One of the most common questions I receive is: "Are there any good new pecan cultivars I need to graft?".  The fact is that pecan cultivar development and testing is a slow process. 'Kanza', today's most popular northern pecan cultivar, was created in 1955 when the USDA's pecan breeder, Louis Romberg, applied 'Major' pollen on a 'Shoshoni' pistillate flower. It wasn't until 41 years later that 'Kanza' was named and released for propagation in 1996.
     Originally, 'Kanza' nuts were regarded as too small and not the proper shape for a commercial pecan cultivar. Pecan scientists across the south began removing 'Kanza' from their cultivar trials. A single tree was grafted to Kanza at Pecan Experiment Field in 1964 and that tree now stands proudly as the oldest Kanza tree in the country. The moral of this story is, that sometimes, its takes decades to see the true value of a new pecan cultivar.

City Park
    That brings me back to potentially new pecan cultivars. This fall I collected some nuts from the pecan clone we have called 'City Park' (photo at right). The nuts on the left in the photo were collected from a tree planted in 2002 and roughly 4 inches in diameter. If I were to judge this clone by this nut sample alone, I would probably discount 'City Park' as no better that a good native pecan. The nuts on the right in the photo were collected from the original tree that I planted back in 1982. The larger tree, with a more extensive root system, was able to capture more water from the soil in this dry year and produce larger nuts. These larger nuts are more impressive and are the reason we have moved 'City Park' into advanced testing.

    During a dry summer, nut size will be related to tree size. The photo at left shows Kanza nuts collected from two different size trees. Again the samller tree produced smaller nuts (not by much). The question becomes: "How big does a pecan tree need to grow before we start seeing a cultivar's full potential in terms of nut size?".  From my experience and the photographic evidence shown here, I'd say a pecan tree doesn't reach it full potential until it grows to over 10 inches in trunk diameter.
    One of the reasons it takes so long to develop and test new cultivars is because it takes 18-20 years to grow a pecan tree to 10 inches in diameter. However, waiting until a clone reaches it full potential is the only way to be certain a cultivar will perform in the long run.