Nematodes are a soil borne parasite that damage the tree by feeding on the roots. Trees with high populations of nematodes may show stunted growth, low yields and water-uptake related problems. Because nematodes may be present in the soil prior to planting, it is advisable to investigate the previous planting history at each location and test the soil. Lesion and ring nematodes cause the greatest damage to walnut production.

Phytophthora citricola is a plant pathogen. Phytophthora citricola infects the root crown and lower trunk and limbs of older trees, causing diseases called Phytophthora canker, Citricola, Citricola canker, Phytophthora canker and collar rot, or Phytophthora canker and crown rot.

Phytophthora cinnamomi is a soil-borne water mould that produces an infection which causes a condition in plants called root rot or dieback. P. cinnamomi lives in the soil and in plant tissues, can take different shapes and can move in water. Root Rot leads to Mycelia growth throughout the root absorbing carbohydrates and nutrients, destroying the structure of the root tissues, "rotting" the root, and preventing the plant from absorbing water and nutrients.

Phytophthora citricola damages trunks and limbs and only the larger roots, while P. cinnamomi, which causes Phytophthora root rot damages small roots.

Texas black walnuts (Juglans microcarpa) have been found to exhibit elevated resistance to A. tumefaciens (crown gall). By crossing Texas black walnuts with English walnuts, it creates a hybrid that continues to exhibit tolerance to crown gall. .

One Year Seedling

RX1 in Heavy Soiil

Tissue Culture Cloning

Texas black walnut X English walnut
Grows in Many Soil Types
Resistance to Phytophthora citricola
Resistance to Phytophthora cinnamomi
Excellent survival in orchard replant trials

Paradox Rootstock
Black Line Tolerent

Original Vlach Tree

Paradox (NCB x English) walnut rootstock
Exceptional vigor
Tolerance to nematodes
Some resistance to Phytophthora
Excellent survival in orchard replant trials

Self Rooted Chandler
Chandler on own Root - No Graft
Little to No Crown Gall

Paradox Rootstock
Vigorous Good survival
Phytophthora –variable response
Susceptible to nematodes
Some resistance to crown gall

Golden Roots Nursery