Friday, November 30, 2012
When I collect samples for evaluation I start by pulling a random sample of a singe cultivar out of a sack of cleaned nuts. The photo above shows a sample I pulled from our Kanza crop. They are all Kanza nuts but they still vary in size and shape.
For evaluation purposes, we require a 30 sample. Place your sample in a paper bag that is marked with your name and the name of the cultivar. Samples should be sent to: Pecan Experiment Field, 8960 SW 90th Str., Chetopa, KS 67336. We are also interested in evaluating outstanding nuts produced by seedling trees.
Saturday, November 24, 2012
One of the greatest challenges facing pecan breeders is predicting how a new cultivar will perform over the long run. And by long run, I mean 30 years and more. History is full of pecan cultivar that looked great as young trees only to fall apart in a mature orchard. Shoshoni, Chickasaw, Mohawk, and Maramec are a few examples that come to mind.
So every year I watch this old original Kanza tree for signs of weakness. So far, this single Kanza tree has been extremely reliable, producing nuts every year with no sign of production problems. This year's crop was no different (photo above) and provides more evidence that Kanza is a cultivar for the long run.
Wednesday, November 21, 2012
In the photo at right, a Major scion was grafted about 4 feet up into a native pecan tree. Note the slight bulge at the graft union and the fact that the Major top has a larger diameter than the native rootstock. This tree was originally grafted way back in the late 1950's and is currently about 2 feet in diameter. This is also the only Major tree on the research station that has out grown its rootstock.
Major trees tend to grow more vigorously that other northern pecan cultivars. Major trees that we grafted on to Giles seedling rootstock back in 1983 are nearly the same size as the Major tree pictured here. It became obvious to me, that the Major tree in the photo, was being dwarfed by a inferior rootstock.
I shook the tree and found its nut production to be similar to other Major trees of equal trunk size. The problem is, at 55 years old, this Major should be closer to 30 inches in diameter. As far as I can tell, the inferior rootstock has had only one effect on the scion cultivar--it has slowed tree growth. However, slower tree growth means the tree is slower to come into bearing age and has less cumulative nut production over time.
On my farm, I have hundreds of volunteer pecan seedlings that could be grafted. But which ones should I use? Will I be condemning certain scions to a life of perpetual slow growth if I choose the wrong seedling? How can I tell?
I only graft seedlings that have demonstrated a strong growth rate--2 feet of new growth in a single year. If a tree seems to be struggling to grow as a sapling, it is a pretty sure sign that tree will not provide a vigorous enough rootstock for any scion cultivar.
Sunday, November 18, 2012
You can find both types of kernels produced by the same tree. Without enough available water this past summer, the tree was unable to completely fill out the kernels of all nuts produced.
I've tasted both normal and darkened kernels and found little difference in flavor. However, the dark blotches can be a big "turn-off" to consumers. If Pawnee had just produced some kernels with less than perfect kernel fill and no color changes, no one would probably notice. Blotchy kernel darkening associated with incomplete nut fill seems to be unique to this year's Pawnee crop.
Wednesday, November 14, 2012
incomplete ripening seems more prevalent on trees with heavy crop loads. It's a terrible shame to waste these perfectly good kernels but if the shucks stay firmly attached the nut, the nut is unmarketable. Fortunately, stick-tights with good kernel inside are far fewer in number than the numerous stick-tights we are seeing being blown out of the cleaner (nuts with little or no kernel).
Friday, November 9, 2012
During a drought, some heavily bearing trees "choose" to fill only a portion of their crop. Those pecans that do not fill their kernels do not shuck-split properly. We saw the same phenomenon when we harvested our "Posey" crop.
Thursday, November 8, 2012
A few days ago I was out in a hydraulic lift making nut counts and couldn't resist talking a photo of pecan harvest from a bird's-eye view (photo above). From 25 feet up into the canopy of our trees, the harvester looks so small.
Tuesday, November 6, 2012
Giles has a tendency to over-produce. This leads to all the typical problems associated with alternate bearing including poor kernel quality during "on" years and next to zero crop during "off" years. However, this year we've seen a new problem with our Giles trees--incomplete ripening. A quick survey of Giles nuts still hanging from the tree reveals that some nuts have split shuck normally while others have not opened at all (photo above, right). At this point in the season, the nuts have have failed to split, will never open.
I peeled out some of the "stick-tight" nuts and cracked open the shells to see if poor kernel development was the reason for lack of proper ripening (like we saw with Posey). In every case, the kernel in the sticktight nuts were just as well filled out as nuts that ripened properly. Something else was causing sticktights.
Earlier this summer we recorded the amount of fruiting shoots produced by 20 of our Giles trees. These counts revealed a wide variation in crop load. We had Giles trees with as low as 16% fruiting shoots to as high as 70% fruiting shoots. To see if crop load influenced the amount of incomplete ripening found on a Giles tree, I decided to climb into the hydraulic lift and make some nut counts. My results can be seen in the graph above. The heavier the crop load (greater % fruiting shoots) the more incomplete ripening or stick-tights we found in the trees.
Incomplete ripening due to fruiting stress may occur in other cultivars but it is most pronounced with Giles. The drought we experienced this past summer may have also contributed to making the problem worse in 2012.