AMERICAN JOURNAL OF BOTANY 
[Vol. 9, 
disposition due to a too vigorous growth in early life. Biffen (1912), in his 
studies on the inheritance in wheat of rust resistance to Puccinia glumarum, 
found that the rust is most virulent when a complete fertilizer is used, and 
that the virulence of the disease decreases with a decrease in the amount 
of fertilizer. Comparing the two principal types of asparagus soils in 
California, the sediment and the peat. Smith (1905, p. 56) notes that aspar- 
agus growing in the latter soil is considerably more damaged by the same 
amount of disease. He comments that on peat formations, composed 
almost entirely of vegetable matter and water, a very luxuriant, quick- 
growing, tender, and succulent asparagus is produced. 
Zavitz (191 3) reports some very interesting observations on the relative 
susceptibility to rust of oats grown under conditions of varying thickness 
of seeding. The experiment was conducted through each of four years, 
using both large and small seed of heavy-stooling, medium-stooling, and 
light-stooling varieties of oats, and planting the seed of each variety in 
squares one, two, three, four, six, eight, and twelve inches apart. Table i 
is adapted from the data presented by Zavitz, and presents the average 
results of thirty-two tests made by planting oats at seven different distances 
apart. The results are the averages for four years. 
Table i 
Inches 
Number of 
Height 
Per- 
Days 
Relative Yield per Plant 
Per- 
between 
Heads per 
in 
centage 
to 
centage 
Plants 
Plant 
Inches 
Lodged 
Mature 
Straw 
Grain 
Rusted 
I 
I.O 
20.4 
5.6 
91 
100 
100 
II. 8 
2 
I.I 
27.8 
II.9 
93 
361 
457 
15.0 
3 
1-3 
32.6 
12.8 
94 
782 
1,227 
17.8 
4 
2.0 
33-1 
29.9 
95 
1,179 
2,031 
20.9 
6 
4.2 
35-3 
35-8 
97 
2,823 
4,402 
254 
8 
6.5 
34-9 
34-7 
99 
4,389 
6,645 
27.7 
12 
II. 2 
34-9 
30.1 
100 
8,475 
10,320 
33-2 
The greater amount of rust observed with the increased distance between 
plants is best correlated with the increased luxuriance of growth exhibited 
by these plants. The difference of a week in the time of maturing between 
the most closely spaced and the most Hberally spaced oat plants is hardly 
sufficient to account for the difference in the amount of rust infection. 
Observations were made at frequent intervals through the summer, and 
a rust difference due only to difference in time of maturity would not have 
shown up in this fashion in the data. A more logical explanation is the 
increase in the amount of lodging which closely parallels the increase in 
percentage of rust from the one-inch spacing to the six-inch spacing. But 
from the six-inch spacing to the twelve-inch spacing the amount of lodging 
decreases appreciably while the percentage of rust increases further, indicat- 
ing that the increase in the amount of rust is independent of lodging. There 
