Hybrid Hickory Variety Recommendations and Propagation Trials

View the project final report

Commodities

• Nuts: Hickories

Practices

• Crop Production: agroforestry

This project researched two main barriers that are critical to surpass in order to make hickories a crop in the upper midwest.

1. Tree evaluations were done on hundreds of hybrid individuals in the upper midwest to provide variety recommendations for growers in the upper Midwest. Previously, only a small handful of subpar hickory selections have been made and often have been trialed only outside of zone 4/5 upper midwest. Additionally, evaluations are almost entirely anecdotal and insufficient to give growers security in planting varieties that are of high cost and may take over a decade to bear nuts.
2. Development of a procedure for epicotyl grafting hickories (grafting onto a sprouted nut) in zone 4/5 has made major headway. Traditional nursery growing of hickories is challenging and problematic due to the high costs of producing grafted trees because of slow seedling shoot growth, strong taproot dominance, and the stress responses of hickories.

The first objective was to select 10 hybrid hickory varieties to be recommended to growers in zone 4/5 upper midwest that will provide maximum profitability and flexibility to the grower and release them for sale. I will select hickory trees that are, ideally, easy to propagate, fast growing, disease resistant, heavy bearing, easy to harvest and husk, and bears multipurpose nuts. A multipurpose nut that grows in zone 4/5 upper midwest can only be found in some hybrids. A multipurpose nut is one that can be used for multiple of the following purposes: home-scale cracking, machine cracking, oil pressing, and milking. The characteristics that allow for a combination of these four purposes are:

• the kernel weight should be as large as possible
• the nut should have a thin enough shell that it can be pressed in-shell for oil reliably (~48% kernel)
• the nut should crack out exceedingly well in a home scale hand cracker
• the nut should be milkable which requires that the kernel, pellicle, and shell not to contain tannins.
• The nut shape should lend itself to automated machine cracking.

The second objective of this project was to determine the details in the procedure of epicotyl grafting hickories to get maximal grafting success. Though I have successfully epicotyl grafted with Black Walnut and the method has been successful with pecan, epicotyl grafting was not previously applied to bitternuts, shagbarks, or their hybrids. Many specifics of the epicotyl grafting process with hickories needs to be discovered including: the best rootstock, the best shoot development stage for high graft success and rapid growth, the best waxing and compression method, and the lowest input nursery growing conditions that work with the Wisconsin climate.