hoice of a wax and wound dressing. In
a series of carefully controlled tests, Sitton (23), found that a rosin
and beeswax mixture with a filler gave results with pecans superior to
the so-called "cold waxes" or asphalt emulsions. Paraffin and polyvinyl
resin are often used for scion covering and to protect newly set buds.
Shelton (20) has indicated certain qualities of a satisfactory wax.

The Rootstock Problem

In the Pacific Northwest Painter (16) stated that some Persian walnut
varieties on _Juglans hindsi_ (the northern California black walnut)
develop a fatal graft blight due to delayed incompatibility at about 20
years of age. This is the so-called black-line disease. McKay (12) found
great differences in survival of buds of Chinese chestnut placed on five
seedling strains and Hardy (8) suggested that more attention should be
paid to the parental relationship of stock and scion in the chestnut.
Weschcke (28) reported that black walnuts grafted on butternuts yielded
poor crops and that bitternut was a satisfactory stock for shagbark
varieties and shagbark hybrids. Smith (25) advocated shagbark stocks
for shagbark varieties but found bitternut to be practically as good.
Stoke (26), and Smith (25) found eastern black walnut to be the best
stock for all walnut species, including heartnuts and butternuts.

Nursery Practices

Commercial nurseries have adopted various methods to discourage the
normal tap-rooting habit of nut trees and stimulate lateral and fibrous
root production. Planting seed over screen wire, undercutting the
seedling each year in the nursery row, frequent transplanting, and root
pruning are methods commonly used. Attention must be given to the
production of an adequate root system to help the grafted tree withstand
the shock of transplanting to its permanent location.

Summary

The chief obstacle to the large scale growing of selected nut varieties
is the difficulty in propagation. Careful workers with a background of
knowledge and experience and skilled in craftmanship are successful in a
limited way. Quantity production is apparently dependent upon
specialized facilities and efficient labor programs. The need for
extensive rootstock research is keenly felt by growers of walnut,
hickory and chestnut.

Literature Cited

1. Barton, Lela V.--Seedling Production in _Carya ovata_, _Juglans
cinerea_, and _Juglans nigra_. Cont. Boyce Thompson Inst. _8_:1-5. 1936

2. Becker, Gilbert--Note