504 
Journal of Agricultural Research 
Vol. XXIX, No. 10 
Table III.— Results obtained from selecting D 74 cane for tolerance to mosaic 
T 
• 
i 
Percentage of mosaic during the season 
Yield in 
Y ear 
Selection 
tons per 
May « 
June 
July 
Septem¬ 
ber 
acre 
1921 b_ ‘ 
f Unselected._ 
_ 40.0 
63.0 
\Selected. - 
30. 0 
28. 0 
j 
1922_ 
f Unselected _ . 
_! 88.7 
100.0 
100.0 
166.6 
10.58 
\Selected.... .. .... 
_1 58.0 
94. 1 
90. 0+ 
100.0 
14.00 
1923. * 
f Unselected_ 
' 
96.8 
100.0 
100.0 
8. 85 
\ Selected.i 
85.9 
100.0 
(<0 
11. 90 
1 
° The percentages for May are too low on account of the very many small plants on which the mosaic 
could not be estimated satisfactorily. 
b For 1921 the figures show only the percentages of pronounced mosaic. Most of the data for that year 
were lost by fire. 
c A satisfactory count could not be made in September, 1923, since so many of the selected plants showed 
the disease in so mild a form. 
Table IV.— Results obtained from selecting Purple cane for tolerance to mosaic 
Year 
1921 
1922.. 
1923.. 
' Unselected 
.Selected... 
jf Unselected 
j\Selected.._ 
!f Unselected 
jlSelected--. 
Selection 
Percentage of mosaic found during the 
season 
' "| ' . : .. , . 
May« ; June j July ^bei’ 11 * 
Yield in 
tons per 
acre 
45.0 
25.0 | 
93.6 i 
69.1 j 
, 95.0 
J 52.0 
( 
I 
100.0 
100.0 
100.0 
17. 37 
75. 9 ; 
90.0+ 
( c ) 
19.89 
100. 0 | 
100.0 
100.0 
18.5 
82.2 S 
100.0 
(*) 
19. 7 
f 
« The percentages for May are too low on account of the very many small plants on which the quantity 
of mosaic could not be estimated satisfactorily. 
b For 1921 the figures show only the percentages of pronounced mosaic. Most of the data for that year 
were lost by fire. 
« A satisfactory count could not be made in September, 1922, in the selected plat since less than 10 per cent 
of the plants showed clear-cut mosaic symptoms. 
d A satisfactory count was impossible in September, 1923, in the selected plat on account of the poorly 
developed mosaic symptoms. 
RESULTS WITH PURPLE CANE 
On the Purple cane the mosaic 
appears in the ordinary light-colored 
stripes which are characteristic of this 
disease on many varieties. On severely 
affected plants these stripes constitute 
more than 50 per cent of the leaf 
surface and, consequently, the plants 
have a yellowish appearance rather 
than the normal dark green. Selections 
were made in the same manner as with 
the D 74 variety. The results are 
given in Table IV. 
The contrast between the selected 
and the unselected row in the Purple 
plats was more striking than in the 
D 74 plats. The selected rows were 
dark green in color and had the ap¬ 
pearance from a little distance of being 
perfectly healthy. Since these plants 
were also taller, there was a striking 
difference in the appearance of the 
different rows. At some seasons it was 
impossible to make mosaic counts on 
the selected rows because of the poorly 
developed mosaic symptoms. On a 
great many of the plants even at the 
EXPLANATORY LEGEND FOR PLATE 1 
Mosaic appearance of sugar cane leaves from plats planted with selected and unselected cane: 
A. —The white dot effect of the disease on D 74 cane; a from the selected cane, b from 
the unselected. 
B. —Average condition of D 74 leaves from selected and unselected plats; a, from the selected 
cane, b and c from the unselected. 
C .—Average condition of the leaves of the Purple variety from selected and unselected plats; a 
from the selected cane, b and c from the unselected. 
