able of adapting themselves to soil and climate where they are to be
planted and of resisting diseases that may attack them under unsanitary
conditions or under too intense cultivation. Among the numerous
varieties tested, two deserve attention as choice rootstocks, one
native, the other American = _J. regia_ and _J. nigra_.

_J. regia_, our old Royal Walnut, so common in France, is excellent when
planted in new, light and fertile soils, preferably clay-lime or
clay-silicon.

But as the roots are very spreading it is important to stir the soil
well but slightly and avoid deep plowing, for it is well known that
through accidental injury to the roots the various "armillaria" enter
the trees to develop the "pourridie" or "pus disease", or "circle
disease". It is better, then, to use a rootstock immune to this malady
so wide-spread among our native walnuts.

_J. nigra_ enjoys this happy advantage of offering no foothold to this
parasite, so harmful to its sister species. It accommodates itself well
in many soils in which _J. regia_ will grow, even dry and gravelly, but
prefers soils which are fresh, open, rich, and especially, deep. Its
roots are long and vertical and their development stops in contact with
an impermeable layer of soil.

It produces specimens magnificent in height and rapidity of growth.
Color of bark differs, though diameter of tree is more or less the same.
This slight objection may be easily avoided by grafting regia on nigra
at ground-level when wood is well matured and in mild weather.

Proof that this species of walnut is resistant to "pourridie" was given
in a report to members of the Congress of Grenoble in 1936 by Mr. Bourne
of Saint Marcelin. "At Blache de Vinay, we are told, some black walnuts,
planted more than thirty years ago in an infested field, have shown full
resistance. One tree, grafted at ground-level and planted too deep, was
infected many years ago by the "pus" above the graft on the _J. regia_
part. The diseased part was treated as was the custom then, with
sulphuric acid, etc. The wound healed and the rootstock remained
absolutely clean. A photo by Mr. Roy, Director of Agricultural Services
at Isere, establishes this absolute proof.

Other varieties of walnut have been tested as rootstocks--_cinerea_,
_cordiformis_, and _Siebodiana_, but only the first seems to have given
any satisfactory results.

Reporter Bourne concludes, "The primary purpose of our research on
rootstocks