Webber: The Improvement of Root-Stocks 299 
as the apple. In Australia and South 
Africa Northern Spy roots have been 
found to be resistant to the woolly aphis, 
and apple varieties are now largely 
propagated on thisvariety.®> Professor 
J. K. Shaw has recognized the im- 
portance of this problem and has con- 
ducted extensive experiments in the 
attempt to grow apple trees on their 
own roots.® 
Apple varieties are largely grafted 
on the French crab or cider apple 
stocks, the seeds or plants of which are 
obtained in large numbers from France. 
Several years ago a considerable num- 
ber of the different types of these cider 
apples were selected in France by 
Professor Alwood and two trees of each 
of these different types are now grow- 
ing in the variety orchard of the U. S. 
Department of Agriculture at the Ar- 
lington Farm near Washington, D. C. 
In November, 1919, the writer had the 
privilege of making observations on 
these different types in company with 
Professor L. C. Corbett and Dr. D. N. 
Shoemaker, horticulturists of the De- 
partment. The variations in the dif- 
ferent types are fully as extreme as 
those found by the writer to exist in 
citrus fruits. These trees are of the 
same age and planted on comparatively 
the same soil and yet some of them are 
dwarfs while others are giants. As an 
illustration the two trees of the Julien 
de Paulmier are much larger and more 
vigorous than those of the Marechal. 
®Cole, C. F., in Journal Agriculture Victoria, Vol. 9, 1911, p. 338. 
The propagation of apple trees on their own roots. 
6Shaw, J. K. 
Experiment Station, Bulletin 190, 1919. 
Photographs, of the same comparative 
size, of trees of these two types were 
made at the writer’s request by Dr. 
Shoemaker and are reproduced in Fig- 
ure 4. Seedlings grown from fruits 
of the Marechal could scarcely be ex- 
pected to give the same results when 
used as stocks as seedlings from the 
Julien de Paulmier. Yet if the writer 
is correctly informed the seed we use 
in growing apple stocks are likely to be 
taken from many different types which 
are probably as markedly different from 
each other as are these two. We may 
desire to use a dwarf stock in some 
cases and a giant stock in other cases 
but certainly we should know what we 
are using. 
In the propagation of grapes the 
specialization has been carried much 
farther and here a great fund of infor- 
mation has been obtained showing that 
with certain varieties only certain hy- 
brid stocks will give good results and 
that on some soils only certain stocks 
may be successfully employed. 
In fruit industries where the trees 
may grow for many- years, possibly 
even for a century or more, and where 
continued success depends as much on 
the stock used as on any other single 
factor, is it too much to require that the 
stocks used should be of known quality? 
The writer maintains that all trees 
should be propagated on selected stock 
varieties of known origin and kind. 
Massachusetts Agricultural 
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