- Author: Elizabeth J Fichtner
- Author: Santosh Bhandari
- Author: Jennifer Randall
- Author: Richard Heerema
Walnuts and pecans represent two of the four major nut crops grown in California. The California walnut industry dwarfs the state's pecan industry in acreage, with over 300,000 acres dedicated to commercial walnut production and approximately 3,000 acres to pecan. The relatedness of the two crops has facilitated an overlap of specialization in the grower community, with many long-time walnut growers also managing the state's pecan acreage.
Walnuts and pecans are both in the same plant family (Juglandaceae); consequently, they have similar reproductive habits. They are both monoecious, meaning that male and female flowers are borne on the same tree. Also, both pecan and walnut produce male flowers called ‘catkins' (Figure 1), and the non-showy female flowers are produced at the terminus of a preformed shoot (Figure 2) that emerges from a compound bud. On walnuts, the catkin buds are visible at nodes, sometimes with two catkins occupying a single node as a primary and secondary bud (Figure 1A). Conversely, the catkin buds on pecan are not readily visible before bud break (Figure 1B). During the delayed dormant phase on pecan, the catkins are hidden behind a scale sheath that covers the catkins and compound shoot bud (Figure 1 B and C). As a result, the catkins only emerge as the entire bud assemblage pushes, generally in late March-early April in California. The compound bud, containing the current season's shoot and female flowers, is assembled with catkins that emerge in groups of three (Figure 1C and 2B). As a result, groups of catkins mature at the base of the current season's shoot (Figure 2B).
The compound buds of walnut and pecan are similar in that the bud contains the preformed shoot and preformed leaves as well as the female (pistillate) flowers. The female flowers are located at the apex of the preformed shoot (Figure 3 A and B). Walnuts and pecans both have variable numbers of pistillate flowers in each compound bud. Walnut flowers are readily visible with the naked eye, whereas pecan flowers are smaller, and observation of the stigmatic surface may be enhanced with the aid of a hand lens. The final nut set of each compound bud varies based on the number of initial pistillate flowers and the success of pollination and fertilization processes.
Both walnut and pecan tend to exhibit apical dominance as evidenced by the stronger, and often earlier, growth of the apical bud. In walnut, two buds (primary and secondary) may be present at each node. Usually, one bud will dominate and grow, while the weaker bud will remain static or die off. Occasionally, both primary and secondary buds grow, resulting in branching at acute angles, often referred to as “forking”. In walnut, nut set can be evaluated by early June and buds for the next year's crop may already be visible in May (Figure 4A). In vigorous orchards, in-season growth may be produced beyond the position of the nuts (Figure 4B). In-season (neoform) growth is less common in pecan. Researchers speculate that the neoform growth observed in walnut may be related to the use of vigorous hybrid rootstocks.
Although pecan and walnut are related species hailing from the same plant family, their growth and reproductive habits do have notable differences. Growers with a lifetime of experience with walnuts may be baffled by the lack of visible catkins on pecan during the dormant season. A bit of patience in the spring, however, reveals the reproductive structures upon bud break. The need for patience in pecan cultivation is also notable at harvest time. In California, the pecan harvest generally commences after the walnut harvest is complete and often continues into the successive year as fall rain events may impede orchard access.
- Author: Peggy Smith
My mother, in all her wisdom, once sent me a wooden garden stake that said, “I tried… but it died”, when I take somewhat drastic measures to try to save something in the garden, I always bear that in mind.
Our pomegranate came with the house when we moved in the 70s and has provided us with a great crop every year and the best jelly. It always just grew like a weed each year and I left it to its own devices with growth above the garage roof height so that it provided some roof shade in the summer's heat, only pruning to keep the path clear and to minimize debris in the gutters.
Times change, a fence and the neighbor's major plumbing work was one blow to the roots too many and the pomegranate lost all its vigor. Combine that with this piece of roof being prime solar panel real estate it looked as though it was time to say goodbye. The dead wood, weak and what appeared to be dying top growth was surgically removed with a chain saw to leave just a tall stump that I would figure out what to do with later. Not a practice conducive to prolonging life.
The bare and barren stump sat quietly through a winter then pushed shoots in many places, should I whack it back and remove the stump? Or should I acknowledge Mother Nature's tenacity and see if I could have both pomegranates and solar roof space?
Espalier seemed to be a solution, but it's a process that is usually begun with a young shrub or tree and then each year the growth is guided and encouraged until maturity. This seemed to be asking a lot of what used to be a proud and vigorous mature tree.
The first year, I selected some of the new shoots to become the future espalier structure, pruning out other multiple shoots so that those that remained could strengthen and become dominant. I also considered I had to leave enough foliage to support the hopefully improved and healthy tree. Some thrived others did not, so again I pruned to the strength of the growth. I gently bent the shoots to roughly where I would like them to extend then sat back and waited for another year's growth. This year, I was able to choose and form the new ‘limbs' into a somewhat idiosyncratic espalier along the fence. Not necessarily something that would win a prize for form in a garden show but hopefully they will thrive and will continue to provide us with those beautiful jewels of pomegranate seeds for the best jelly.
Pomegranates are notoriously resilient, growing like weeds, this would not have worked with say a peach or a pear. Now I wait in great anticipation for the first flowers, and if there's enough fruit, I'm sure this year's jelly will taste the best we've ever had!
- Author: Karen Metz
My mother bought me the cutest pink flowering plant in a little 2-inch bunny planter for Easter. She told me that she thought it was the prettiest Kalanchoe that she had ever seen. It was adorable, and just bursting with flowers. I was a little puzzled though. The leaves looked like classic scalloped Kalanchoe leaves, but the flowers were different. They looked like a supercharged Kalanchoe on steroids. I noticed that the label on the bottom of the planter said Calandiva.
The World of Succulents website and the Calandiva.com website helped to clear things up. Kalanchoe blossfeldiana is the scientific name for the typical florist Kalanchoe that we all know and love. It has 4 petals to each blossom. In 1998 a grower found a mutant plant whose blossoms had 32 petals per flower. After 4 years of research and careful breeding, growers were able to release this cultivar to the public as Calandiva. So, the official scientific name is Kalanchoe blossfeldiana ‘Calandiva'. It is now available in many colors and is extremely popular.
It is only hardy in USDA zones 10-12, so for most of us, it is grown as a houseplant. Calandiva needs essentially the same care as other Kalanchoe. They need light to flourish. They also need well-draining soil and to be able to dry out between waterings.
Now that I knew what I was dealing with, I looked at my Calandiva and noticed that this full, tall, blooming plant was in a small 2-inch pot. Sure enough, when I turned it over, roots had grown out the bottom. So, I repotted it in a 4-inch pot so it will have some room to stretch out. It seems to be very happy in its new home. According to the experts I can expect to enjoy the blossoms for 4-6 weeks. Thanks, Mom!