Its that time of year when you can look up at a pecan tree and see thousands of catkins dangling from limbs (photo at right). Plentiful catkin production is a good indicator of a healthy tree but it is not related to the number of nuts a pecan tree will eventually produce. To determine the potential for a pecan crop this Fall, you'll need to inspect the terminals of the new growth and check for female flowers.
When I checked my trees yesterday, I found that pistillate flowers on protogynous cultivars were easily seen and appear to be ready to accept pollen from a protandrous tree. The photo at left shows a cluster of Jayhawk female flowers. Each female flower is topped by a feathery stigmatic surface that is designed to capture pecan pollen out of the air. Below the stigma are four leaf-like sepals that stick out in right angles. Below the sepals is the pecan fruit that contains the ovule and egg. When a pollen grain lands on the stigma it germinates and grows down through the flower entering the ovule before eventually uniting with the egg to form a new pecan seed.
The catkins on protandrous cultivars were just starting to mature and release their pollen into the air. The photo at right shows some Gardner catkins that have just started to open their pollen sacs. As pollen sacs mature, they change color from green to yellow. As they dry in the sun, pollen sacs split open and release pollen. Once the pollen has been released the pollen sac will turns brown in color. As you can see, not all pollen sacs release pollen at once. Most pecan cultivars will release their pollen over a 5 to 6 day period.
Even though they are not very prominent, you should be able to see the beginnings of pistillate clusters on protandrous cultivars. The photo at left shows a flower cluster forming on the Gardner cultivar. Note that at the flowers are still tiny and not fully formed. By the time Gardner pistillate flowers become receptive they will be very large and topped with a bright red stigmas (that will be 10-14 days from now).
There is one more observation you can make about pecan flowering at this time of year. The photo at right shows a Kanza flower cluster. The red arrows point to fully formed and receptive pistillate flowers. At the terminal of this flowers cluster are 2 incompletely formed flowers (blue arrows). As pistillate flowers were set on this new flowering shoot, the pecan tree actually ran out of resources to fully form the top 2 flowers. These ill formed flowers will eventually dry up and fall off the tree.
