Gbe 'national Utarseryman. 
Vol. XXVIII. 
WERS AND DEALERS IN NURSERY STOCK 
The National Nurseryman Publishing Co., Incorporated 
HATBORO, PENNA., SEPTEMBER 1920 
No. 9 
Aphis Resistent Apple Stocks 
John Watson, Secretary American Association of Nurserymen. 
In the course of his remarks at the Chicago Conven¬ 
tion, Professor Corbett, Horticulturist of the Bureau of 
Plant Industry, Washington, touched upon a subject of 
very vital interest to orchard ists and therefore to nur¬ 
serymen. Of course, all that Professor Corbett and Dr. 
Galloway and Mr. Coville said was of immediate inter¬ 
est bearing as it did on the necessity to produce our own 
raw materials in this country and outlining the proposed 
Governmental work planned to assist and point the way 
to do that; but Professor Corbett referred to a subject 
that nurserymen may well consider now: the production 
of aphis-resistent stocks. There are very great and pro¬ 
fitable possibilities in that direction for the grower will¬ 
ing to pioneer into new fields and blessed, as he must be, 
with patience. We all know that woolly aphis is a very 
serious and a growing problem. In some sections it has 
made apple-growing impossible altogether; in the West, 
and particularly in California, it has caused many nur¬ 
serymen to quit trying to produce apple trees. 
We all recognize the influence of the stock upon the 
scion: how the quince will dwarf the pear and how the 
paradise will dwarf the apple; and it is even more inter¬ 
esting to note the influence of the scion upon the stock : 
apple grafts, for example, of Bechtel’s Crab and of Trans- 
scendant will compel a far better root-system in two 
years than scions of Baldwin or Yellow Transparent on 
seedlings of exactly the same grade. We do not know the 
exact extent of that influence, but we can see its effect. 
Our country is so young, as ages go with countries, 
and we have hurried along at so fast a pace that we have 
not taken time to change many of the old methods; it has 
been too easy to follow the beaten path and to pursue 
tried ways; we have done little experimenting. We have 
not had time for that, nor the money; and we have not 
felt the necessity to do it. In the case of apple trees, for 
example, we have had such a generous and such a wide 
market for the trees and in very nearly every State, that 
we have bent all our energies to quantity production. 
Now, the time must come with us as it always has with 
older countries, when we shall be obliged to work out 
better methods and especially methods that will result in 
better, longer-lived, healthier and more productive or¬ 
chard trees. 
Of all the aphis-resistent stocks, the Northern Spy is 
the best. It is largely used in England, South Africa, 
Australia and New Zealand. I venture the prediction 
that we shall see the time when California will use 
nothing else. In Australia, where woolly aphis is a pro¬ 
lific pest, the nurserymen have over twenty-five varieties 
of resistent stocks; but, with the exception of Northern 
Spy which has been used there for fifty years and which 
furnishes, I understand, fully 95% of the apple stocks 
used, the others are still in the experimental stage or are 
not yet produced in quantity. 
The trouble that we shall experience, if obliged to pro¬ 
duce our own resistent stocks, is our handicap of hurry; 
we want to do things quickly and in the big way; the 
short cut invites us and we demand quick results. We 
cannot get them when we come to grow resistent stocks. 
None of them, not even Northern Spy, can be grown from 
seeds. Of course, the seeds will produce seedlings but it 
is a peculiar fact that the seedlings lose the resistent 
quality and are as prone to aphis as ordinary crab seed¬ 
lings. That has been thoroughly demonstrated. 
The method usually followed by the Australian nur¬ 
serymen is to make root-cuttings of the Northern Spy 
about 2y 2 inches long. The cuttings are planted an inch 
apart in rows iy 2 feet apart; here, we would use the 
wider standard row; or they can be planted in beds. The 
cuttings are planted upright in a warm, loamy soil early 
in the spring and cultivated clean, covered over the tops 
with half an inch of soil. The following season they are 
dug, graded, trimmed and planted in nursery rows, like 
seedlings. Sometimes the stocks are dug around in the 
bed and cut off so as to leave pieces of roots that will 
grow out and make another crop of stocks in the same 
place. 
Others are grown like paradise and doucin: thrifty 
young trees are planted in permanent rows and about 
three feet apart, cut back close to the ground, covered 
and cultivated; as soon as they throw out young shoots 
to a height of twelve inches, the soil is banked up to half 
their height. They root readily at the base and can be 
cut off from the parent stem at oue year or preferably at 
two years, just like doucin and paradise. They are 
handled and planted in the same way as any other 
stocks. The stools will produce a greater number of 
shoots every year but they do not become quantity pro¬ 
ducers until at least four years old. They do not wear 
out and do not have to be replaced but a stool-bed in¬ 
creases in production and value with age. That is why 
we need patience. Stocks grown in this manner from 
Northern Spy similarly grown are immune in top and 
root to woolly aphis to a 100% degree. 
Layers are always more expensive than seedlings; but 
we have to use dwarf stocks to grow dwarf trees and we 
have to use resistent slocks to get trees immune from 
aphis. And neither can be grown from seed. 
Very soon orchardists are going to want and demand 
trees grown on resistent stocks wherever they are 
