Wednesday, January 22, 2020
Recently, I pulled a sample from my 2019 Lakota crop to check on nut quality and determine if I had shaken off enough nuts back in August. I found that 90+% of the kernels appeared plump and fully formed (photo above). However, a few kernels demonstrated the negative effects of a tree carrying a heavy crop (shriveled kernels). During the summer of 2019, we had ample rainfall so I knew that any kernel shriveling would be due to a excessive crop load and not be drought related.
To check on kernel quality, I broke several kernels in half so I could see how well the kernel tissues were packed inside of each nut (photo above). Kernels that appeared plump from the outside had some small air pockets in the center of each kernel half indicating a not-so-perfect fill. Shriveled nut meats had thinner layers of kernel tissue and they had very pronounced air pockets. Several kernels developed hollow backs. These nuts appear plump on the top side of the kernel but the underside is sunken or hollow. The hollow back kernel has a well developed layer of kernel on the top but little or no kernel layer adjacent to the inner wall partition.
After looking over dozens of nut samples from my 2019 Lakota crop, I concluded that summer shaking did improve my kernel quality but I should have shook even more nuts off each tree to achieve top kernel quality. Each year is a learning process when it come to crop load regulation, so hopefully, I'll do better in the future.
Monday, December 30, 2019
This winter, I'm back thinning out more trees (photo at right). At this point in the project, my tree removal objective is to make certain that trees that have the greatest potential to become new cultivars have plenty of room to expand their canopies. The trees in the photo were growing only 20 feet apart within the row (row spacing = 40 feet) with adjacent canopies shading each other. After tree thinning, the remaining trees will be spaced 40 feet by 40 feet.
Thursday, December 26, 2019
Pecan seeds need to go though a process called stratification before they will germinate properly. I start this process by placing all my seed in a large plastic tub (photo above).
The final step in the stratification process is to place the seed boxes into cold storage. Pecan seeds need to be held at 33 to 40 degrees F for 90-120 days before they will germinate uniformly. If you use a standard household refrigerator to stratify your seed, open the lid of your seed box once a month to make sure the potting soil isn't drying out. If the soil feels dry, simply sprinkle on some water to re-wet.
My seed nuts should be ready for planting in late April just as outdoor temperatures start to warm up.
Wednesday, December 11, 2019
Recently a California pecan enthusiast sent me a photo of his failed attempt at top-work a fairly large pecan tree (photo above). He had found my pecan blog online and solicited my advice on how I would approach grafting his tree. Rather than just replying to his email, I though his photo could prove to be a good learning opportunity for many of my readers.
I'll start by pointing out why I think things went wrong. From what I can see, 9 grafts were attached to this tree, each covered in a paper bag, and scattered among terminal branches. From the photo, I cannot tell which grafting technique he employed but I do know that every graft failed. The biggest mistake made in grafting this tree was that not enough of the tree was cut back to force a graft to take. Applying a graft out on the end of a branch simply allows too many places for the tree to grow around the cuts made in grafting. Ultimately, the tree just walls off the scion like it was a broken twig. In addition, I am not a fan of placing a brown paper bag over the graft union and scion. Rather than shading the graft as intended by this method, the bag can cause the scion to get too hot, baking in the every present Southern California Sunshine. Thirty years ago, I visited a commercial nursery that was bagging every pecan graft. I recommended dropping the bagging process and their grafting success increased dramatically.
Now lets look how I would approach grafting this tree next spring. Before making a single pruning cut, I would make sure to obtain some good scionwood cut from a vigorous one-year-old shoot. I would top-work this tree with a single bark graft, so great scionwood is critical. When leaves start to unfurl next spring, this tree will be ready for grafting. In the photo above, I have drawn in the pruning cuts I would make. The cut labeled "A" is the location where I would place a bark graft (directions for bark grafting can be found Here). I would also remove the large 3-forked branch marked "B" to make sure all of the tree's upward growing energy is directed to the graft union. I would leave all the remaining lower lateral limbs in place to shade the trunk and provide valuable leaf area to help feed the root system. In addition, I would also do a little detailed pruning by removing any small branches that are growing strongly upwards (cuts marked "C"). In fact, all summer long I would return to this tree to make sure that the lower lateral limbs only grow outwards not upwards.
After inserting a bark graft into the top of the central leader, I would be certain to attach a 8-foot-long training post to the trunk so that it extends 5 feet above the scion. My goal for this tree would be to get 5 to 7 feet of new growth from the scion during the first summer so I'll need a good sized training stick to support the scion and prevent wind damage.