304 
Journal of Agricultural Research 
Vol. XXVIII, No. 4 
Table III.— Effect of curly-top on the growth of sugar beets —Continued 
s 
o 
Maximum leaf and root dimensions 
Weight on 
Plant 
% 
> 
_ >* 
Leaves on 
May 14 
Root diameters 
July 26 
(grams) 
Date of observation and degree of 
disease when first noted 
Number ol 
Ma 
Width 
Spread 
On May 14 
On June 2 
Increase in 
19 days 
On July 26 
Increase in 
54 days 
Top 
Root 
No. 16., 
24 
Cm. 
12.7 
Cm. 
66 
Cm. 
3.99 
Cm. 
7.28 
Cm. 
3.29 
Cm. 
7.61 
Cm. 
0. 33 
Gm. 
52 
Gm. 
252 
June 2. 
No. 23.. 
12 
14.6 
60 
2.72 
5.25 
2.53 
6.70 
1.45 
83 
207 
June 2, two youngest leaves 
affected. 
June 2. 
No. 26.. 
20 
17.8 
61 
4.69 
8.69 
4.00 
10.82 
2.13 
185 
753.5 
No. 27.. 
19 
14 
69 
3.89 
6.76 
2.87 
8.72 
1.96 
152.5 
449 
June 2, three of younger leaves 
affected. 
June 2, seven of younger leaves 
affected. 
June 2, about half of the leaves 
affected. 
June 2, one young leaf affected. 
No. 28- 
16 
20 
74 
3.61 
6.40 
2.79 
8.20 
1.80 
169 
300 
No. 31- 
15 
16.5 
81 
4.15 
6.99 
2.84 
8.13 
1.14 
19 
425 
No. 37- 
9 
8.3 
55 
1.60 
3.36 
1.76 
4.32 
.96 
22 
64 
No. 9... 
16 
16.5 
69 
3.93 
7.90 
3.97 
10.23 
2.33 
321 
802 
June 2, healthy. 
No. 16- 
12 
14.6 
77 
2.69 
5.25 
2.57 
6.71 
1.46 
68 
300 
Do. 
No. 17- 
13 
2L6 
79 
5.83 
9.76 
3.93 
10.95 
1.19 
301.5 
896.5 
Do. 
No. 24- 
13 
10.2 
53 
2.18 
4.79 
2.61 
8.24 
3.45 
225 
438 
Do. 
No. 30.. 
13 
10.2 
48 
3.11 
5.22 
2.11 
6.46 
1.24 
116 
306.5 
Do. 
DRY WEIGHT OF TOPS INCREASED 
Moisture determinations which were made at three different times of the 
tops or leaves of young healthy and diseased beets show that the proportion of 
dry weight of the tops of young diseased plants exceeds the proportion of dry 
weight of those of young healthy plants by 2.5 to 3 per cent. This excess of dry 
weight is attributed to the excessive accumulation of carbohydrates, probably 
sugars. Due to'the breaking down of the phloem, normal translocation is impos¬ 
sible. The clear, viscous exudate (PI. 2, C) has been repeatedly found by Feh- 
ling’s test after hydrolysis with an acid to contain a complex sugar, probably 
saccharose. In only one or two instances were traces of reducing sugars detected. 
The escape of the exudate by rupturing the tissue is attributed to the high pres¬ 
sure developed by the abnormal accumulation of the sugars. 
Table IV.— Artificial inoculations of sugar beets , resulting in no disease ° 
Date 
Kind of inoculum 
Kind and number 
of plants 
inoculated 
Season of 1918: 
March 3_ 
Fresh excreta of the leaf hop¬ 
Two young beet 
per. 
seedlings. 
August 3—. 
Ringer’s solution extract and 
Four young beet 
aqueous extract of young 
seedlings. 
August 12. . 
leaf of curly-top beet. 
Six adult leafhoppers macer¬ 
Three young 
ated in 2 cc. of Ringer’s 
beets. 
Do.. 
solution. 
Curly-top beet leaf macerated 
in Ringer’s solution. 
Curly-top beet leaf macerated 
in distilled water. 
.do. 
Do — 
.do... 
Season of 1919: 
May 24_ 
Pieces of curly-top beet leaf... 
Eight beets (these 
August 8. _. 
Pieces of petiole of leaf of 
had five or six 
true leaves). 
Seven young 
curly-top beet. 
beets. 
Method of inoculation 
Point of steel needle dipped into 
drops of excreta and then pricked 
into plants. 
Sprayed each extract on two 
plants; then caged on each five 
nonviruliferous leafhoppers. 
A drop of inoculum placed on each 
of two leaves of each plant and 
pricked in with small steel 
needles. 
Do. 
Do. 
Placed tissue on midrib near base 
of blade, macerating over and 
pressing into a slit in the midrib. 
Placed tissue on center of blade of 
one leaf of each and then macer¬ 
ated into wound in the blade 
with scalpel and needle. 
a Since this manuscript was prepared curly-top has been artificially communicated by transferring juice 
from diseased to healthy beets, as described in the following publications: Severin, H. P. curly leaf 
transmission experiments. Phytopathology 14: 80-93, illus. 1924: Carsner, E., and Stahl, O.F. 
progress report ON curly-top OF the sugar beet. (Abstract) Phytopathology 14: 122-123. 1924. 
