A grafted fruit tree is made of two separate organisms, two plants that have has bonded together by different methods, e.g. grafting, budding, in-vitro production. The lower part, the rootstock -mostly located inside the soil- provides anchorage and interact between the soil and the variety - terminally growing part outside of the soil. Different Rootstocks are preferred for different soil types and conditions. Each has advantages and challenges when it comes to providing vigor and tolerance to soil conditions, pests and diseases.
Juglans Regia L., sometimes referred to as English or Persian Walnut, seeds planted in soil grows walnut plants. Walnut plants in Europe and Asia are predominantly on Regia seedlings. Regia seedling adapt well to and perform superbly in most normal soil conditions.
On the other hand, they are unable to tolerate certain soil complications like salt and excess of water generally found in flat heavy clay soils with poor drainage. Each seedling is a different genetic organism, which is likely to perform in less uniformity, especially in the first few growing seasons.
Paradox is a hybrid of Juglans Hindsii - Northern Californian Black -and Juglans Regia - English Walnut. They are very vigorous and tolerates heavy, wet, salty or low fertility soils.
Depending on your soil conditions and characteristics, you may need to use more than one rootstock in specific plots of your orchard. And selecting the right combination, is a very important strategic decision, that you need to make right. Confused about deciding which rootstock to choose, let us help. Here are some interesting articles and research papers on rootstock selection.
In addition to their tolerance to more complicated soil conditions, Clonal Rootstocks are often preferred for their ability to create uniform orchards where growth and productivity are more homogenous compared to seedlings where each rootstocks is a different organism with unique characteristics.
Clonal Rootstocks are selections of hybrid seedlings that are cloned in tissue culture laboratories, that replicate the same organic material in thousands of units under controlled laboratory conditions.
Clonal rootstocks are not GMOs (Genetically Modified Organisms), but simply a carbon copy of a selected organism with superior characteristics.
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Vlach is a clonal propagation of an extremely vigorous Paradox tree located in Stanislaus County, CA. During the last 15 years it has become the standard clonal walnut rootstock. Very vigorous and adaptable to heavy soils.
RX1 is a highly vigorous Paradox hybrid clone with Moderate to high resistance to Phytophthora/Wet conditions.
VX211 is a highly vigorous Paradox hybrid clone that outgrew other walnut seedlings in the presence of nematodes.