Mar. 6, 1917 
Little-Leaf of the Vine 
397 
Table) VII .—Results of application of gypsum to a vineyard for the control of little-leaf 
Block and condition. 
First year. 
Second year. 
Vines. 
Per cent. 
Vines. 
Percent. 
Block “A” (no treatment): 
Healthy. 
70 
18 
79-5 
20. 5 
62 
1 6 
70.4 
l8. 2 
Slightly affected. 
More affected. 
Badly affected. 
10 
83 
2 
11. 4 
94.2 
2-3 
Block “B ** (1,000 pounds of gypsum per acre): 
Healthy. 
15 
17.0 
Slightly affected. 
More affected . 
33 
40 
37-5 
45 - 5 
Badly affected. 
3 
3-5 
Winter and early spring irrigation, so far as noted, seem to have little 
or no effect on the disease. The effect of summer irrigation has not been 
well tested. 
Mr. A. Bonnet, of Montpellier, France, has suggested the plausible hy¬ 
pothesis that little-leaf is due to unfavorable changes of temperature, and 
specifically to a period of cold weather checking growth started by a pre¬ 
vious period of warm weather. To test this hypothesis, measures were 
taken to delay the starting of the buds. This was accomplished by late 
pruning, whitewashing, and shading the vines. While a delay of nearly 
two weeks was obtained, no perceptible effect on the disease was noted. 
SUMMARY 
“Little-leaf ” is a disease of the vine, vying in seriousness with oidium 
and phylloxera. It is confined to sandy soil in the great valley south of 
Sacramento County. It seems to be unknown elsewhere, unless a form 
of “court none” noted in northern Mexico and southern Europe, are 
identical. * 
Affected vines show small, yellowish leaves, short-jointed canes, and 
in severe cases dead spots on the leaves and gummy secretions in the 
conducting tissues of the arms and trunks. In severe cases the vines die 
after a few years. Vines slightly affected set fruit imperfectly, and those 
badly affected bear little or nothing. 
No parasite has been found connected with the disease, and the evi¬ 
dence seems to show that it is not infectious. Several species of trees 
are affected with similar symptoms when growing near or among affected 
vines, indicating that the disease is due to local conditions of soil, water, 
temperature, or other nonparasitic causes. 
No-effective method of treatment has been demonstrated, though the 
application of gypsum to the soil is promising. 
