16 
BULLETIN 1484, U. S. DEPARTMENT OF AGRICULTURE 
Table 5. — Comparison of number of crazy-top plants in 10 ,000-square-foot sec- 
tion of field of Acala cotton affected in the same spot for the third year and area 
75 feet distant in field cropped to cotton for the first time since 1920 
Row No. 
Representative; Representative 
section of large section of adjoin- 
crazy-top spot i ing field in cot- 
affected third ton first year 
successive year j since 1920 
1 
Row Xo. 
Representative 
section of large 
crazy-top spot 
affected third 
successive year 
Representative 
section of adjoin- 
ing field in cot- 
ton first vear 
since 1920 
Crazy- 
top 
plants 
Normal C ^ T - 
? lants ! pffis 
Normal 
plants 
Crazy- 
top 
plants 
Normal 
plants 
Crazy- 
top 
plants 
Normal 
plants 
1 . 
9 
10 
15 
5 
15 
13 
12 
14 
19 
13 
13 
10 
6 
11 
16 
9 
29 
16 i 
23 | 
19 
73 
42 
57 
47 
55 
50 
64 
46 
49 
49 
59 
72 
56 
60 
71 
53 
17.. 
10 
12 
n ±0 
2 
18 
29 j 42 
3 
19 8 
20 ■ 7 
21 ! 8 
22 11 
23 1 14 
24 
15 58 
4. 
17 1 1 53 
5 
16 
53 
31 
33 
31 
32 
20 
26 
38 
32 
36 
11 












17 ' 59 
6 
18 | 54 
7 
8 -- 
21 ! 55 
8 ! j 5* 
9 
25 
25 
9 n 1 si 
10 
26 
27 
13 
18 
19 
7 
9 
17 
j 65 
11.. 
1 60 
12 
28 
1 48 
13 
Total 
14 ._ 
345 
35.6 
625 1,554 

15 _. 
Percentage 
16 
" 1 
None of the plants in the 8 acres of the field newly returned to cul- 
tivation showed any crazy-top symptoms, whereas the 10-acre field 
which had been continuously in cotton was severely spotted with the 
groups of deranged plants. The surface soil in the field which lay 
fallow prior to cotton planting in 1925 was more sandy than that in 
the adjoining field where crazy- top was prevalent, and this soil differ- 
ence as well as the fallowing may have contributed to the normal 
behavior of the plants. 
The difference in productiveness of Pima plants affected with crazy- 
top and of those in the more favorable condition following a crop of 
alfalfa is shown in Table 6. 
Table 6. — Difference in productiveness of Pima cotton plants from an area cropped 
continuously for j. years to cotton which was badly affected by crazy-top, as com- 
pared to an adjoining area of cotton following alfalfa 
[The plants were chosen systematically by walking diagonally across the area and selecting the plan t 
nearest the end of every third step] 
9 
1 
Number of mature 
bolls per plant 
Plant No. 
Number of mature 
bolls per plant 
Plant No. 
On con- 
tinuously 
cropped 
area 
On area 
following 
alfalfa i 
On con- j n 
1 
21 
21 
29 
34 
18 
27 
20 
26 
17 
18 
17 
68 
96 
80 
63 
83 
56 
72 
77 
46 
67 
51 
12 
14 53 
2 
13 
21 64 
3 
14 
19 1 80 
4 
15 
25 | 61 
5. . 
16 
27 i 76 
6 ._•- 
17 
24 ! 52 
7.. 
18 
18 j 47 
8 
19 
21 ! 51 
9 
20 
27 57 
10 
11 . 
22.2 65.0 
