390 
Journal of Agricultural Research 
Vol. VIII, No. to 
The difference in size varied with the intensity of the disease, with the 
position of the leaf on the cane, and with the variety (Table VI). 
Table VI .—Comparison of size of healthy and diseased leaves of the vine 
Order of leaf on cane. 
(Length bf healthy leaf)-*-(Length of 
diseased leaf) . 
Petite 
Sirah. 
First 
Zinfandel. 
Second 
Zinfandel. 
2.. 
I. II 
I. 56 
5 .. 
O. 81 
A ... 
I. IQ 
I. 04 
I. 64 
1. 56 
2. OO 
2. 86 
c. 
I. 17 
I. 26 
I. 27 
i- 53 
1.42 
1. 50 
1. 77 
6. . 
7. 
8 . 
I. 60 
I.94 
2.45 
3- 53 
3- 12 
3- 03 
4- 3» 
6. 64 
0. 
10... 
II.,,.. 
12 . 
Means ... 
i-34 
2. 00 
3- 14 
This table shows three degrees of intensity of attack. With the 
Petite Sirah there was little difference in size of leaves up to the fifth from 
the base of the cane. From this point the leaves on the diseased vines 
gradually became smaller, until at the eleventh node the diseased leaf 
was only 56 per cent as long as the corresponding healthy leaf. The first 
Zinfandel shows an increase of intensity. The lower leaves up to the 
fifth showed little difference, but the eleventh on the diseased vine was 
only 32 per cent as long as the healthy leaf. The second Zinfandel rep¬ 
resents a very severe case. Even the lowest leaves were much smaller 
(64 per cent), and the tenth leaf of the diseased vine was only 15 per cent 
as long as the healthy leaf. 
These measurements were made early in May and do not show the 
decrease of intensity shown later by the production of almost normal 
leaves. 
CANES 
As with the leaves, the symptoms on the shoots and canes vary with 
the intensity of the disease. The lower or earlier internodes may be 
nearly or quite normal, except in very severe cases. From the middle, 
and especially on the laterals, the internodes are shortened and flattened. 
The shoots and canes are very erect. This, with the abnormal num¬ 
ber of laterals, gives the vine a bushy appearance, completely changing 
its natural habit. In a vineyard of moderately affected vines the aver¬ 
age length of the shoots of diseased vines was found to be 49 per cent of 
that of the shoots of healthy vines. This corresponds to the average 
difference between the lengths of the internodes, which was in the ratio 
of 100 to 50. 
