•-Apr. 26,1924 
Studies on Curly- Top Disease of th e Sugar Beet 
303 
EFFECT OF CURLY-TOP ON GROWTH 
A plant that becomes infected while young—when the root is perhaps 1 cm. 
or less in diameter—will usually die in a relatively short while or before the 
summer is past, but a plant that is about half grown or larger when infected will 
usually live a long time, as a rule to the end of the season. 
Measurements made during two seasons of the roots of beets affected with 
“curly-top show that increase in size of the root usually continues for a consider¬ 
able length of time, often more than a month after the plant has become evidently 
diseased. The data taken during one season are listed in Table III. The plants 
were grown at Riverside, Calif. Figures are given of the size and number of the 
leaves of each plant, because the vigor of growth of the root is correlated with 
the size of the top. Plants which were evidently diseased on May 14 continued 
to grow, so that by July 26 the roots of most of them had nearly doubled in diam¬ 
eter. The measurements in connection with observations of the affected plants 
indicate that increase in size of roots continues as long as the older leaves, which 
were mature at the time of infection and therefore have remained apparently 
normal, survive. The weight of the top or leaves, as well as that of the root of 
each plant at the time of digging on July 26, is given. These figures indicate 
the great retarding effect of the disease on the growth of the tops. It is of 
interest to note the wide variations in individual plants as to the effect of the 
disease. The variation appears to be greater than that which occurs in the case 
of diseases of many plants. 
Table III .—Effect of curly-top on the growth of sugar beets 
§ 
Maximum leaf and root dimensions 
TT ClgUt OU 
Plant 
i 
* i-H 
Leaves on 
May 14 
Root diameters 
July 26 
Date of observation and degree of 
disease when first noted 
A oS 
Increase in 
19 days 
Number < 
M 
Width 
Spread 
On May 14 
On June 2 
On July 26 
Increase in 
54 days 
Top 
Root 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
Cm. 
Om. 
Om. 
May 14, two leaves affected. 
No. 3... 
10 
10.2 
43 
2.09 
3.57 
1.48 
3.98 
0.41 
27 
78 
No. 6— 
18 
13.3 
56 
3.62 
5.53 
1.91 
6.49 
.96 
62 
207 
May 14, five youngest leaves 
affected. 
No. 8... 
16 
11.4 
52 
3.38 
5.51 
2.13 
5.71 
.20 
49.5 
169 
May 14, one leaf affected. 
No. 12.. 
15 
15.9 
53 
3.10 
4.98 
1.88 
5.85 
.87 
89.5 
272 
May 14, three youngest leaves 
affected. 
No. 19- 
17 
16.5 
64 
3.02 
4.63 
1.61 
5.84 
1.21 
87 
185 
May 14, seven youngest leaves 
affected. 
No. 20.. 
15 
12.7 
62 
3.80 
5.02 
1.22 
5.20 
.18 
43.5 
120 
May 14, six of younger leaves 
affected. 
No. 22- 
18 
15 
56 
3.79 
6.35 
2.56 
7.88 
1.53 
147 
385 
May 14, seven of younger leaves 
affected. 
No. 32- 
15 
13.3 
62 
2.98 
4.50 
1.52 
5.26 
.76 
26 
125 
May 14, three of younger leaves 
affected. 
No. 35- 
21 
10.8 
76 
3.90 
5.32 
1.42 
5.54 
.22 
74.5 
114 
May 14, nine of younger leaves 
affected. 
No. 36- 
19 
20.3 
70 
4.10 
5.97 
1.87 
5.71 
-.26 
22.5 
186 
May 14, four of younger leaves 
- 
affected. 
No. 38- 
12 
10.8 
" 63 
2.41 
3.08 
.67 
2.88 
-.20 
10 
20.5 
May 14, five of younger leaves 
affected. 
No. 2... 
14 
10.2 
46 
2.35 
4.70 
2.35 
7.12 
2.42 
132 
276 
June 2, one young leaf affected. 
No. 4— 
8 
6.4 
47 
1.19 
3.02 
1.83 
4.54 
1.52 
55 
112 
June 2, four of younger leaves 
affected. 
No. 5— 
15 
17.8 
51 
2.77 
5.56 
2.79. 
7.63. 
2.07 
153 
417 
June 2, eight youngest leaves 
affected. 
No. 10- 
10 
8.3 
58 
1.23 
3.10 
1.87 
3.60 
.50 
22 
48.5 
June 2, six youngest leaves 
affected. 
No. 11- 
19 
15.9 
61 
4.62 
7.49 
2.87 
8.06 
.57 
90 
440 
June 2, four youngest leaves 
affected. 
No. 13- 
11 
14 
53 
3.25 
5.78 
2.53 
6.94 
1.16 
175 
380 
Do. 
No. 14- 
10 
15 
66 
3.03 
5.60 
2.57 
7.67 
2.07 
300 
440 
June 2, five of younger leaves 
affected. 
