THE GRAPE PHYLLOXERA IN CALIFORNIA. 109 
below occurred. The soil of the fourth pot was watered sparingly, 
and few cracks were formed. July 17, 12 wanderers were shaken onto 
the soil. No infestation of the root below occurred. Only one out 
of the four experiments resulted positively, and in that one the 
soil was very well cracked, affording access to the root. 
Inoculation of the wanderers on living vines was attempted 
through the following experiments : Five lots of four vinifera vines 
each were planted, two on light sandy loam and three on heavy clay 
loam. The vines were all young rooted vines, and they were planted 
roughly in the form of squares during the month of June. In the 
center in each one of four of the groups a phylloxerated vine (potted) 
was put in the ground at varying distances from the four surrounding 
vines. In one group the four outside vines were distanced, respec- 
tively, 14 inches, 2 feet, 3 feet, 3| feet from the central vine. In a sec- 
ond group they were distanced, respectively, 2, 3, 4, and 6 feet from the 
central vine. In the third group they were distanced, respectively, 
2, 4, 6, and 8 feet from the central vine. In the fourth group they 
were distanced, respectively, 2, 3, 4, and 6 feet from the central vine. 
In the fifth group the four vines were potted, and in place of an 
infested central vine, infested roots were buried 1, 2, 3, and 4 feet, 
respectively, from the outside vines. In this last case the vines were 
potted to prevent possibility of underground inoculation. The four 
central vines remained infested throughout the summer, but it was 
not disclosed that they, or the buried roots, produced any wandering 
larvae above the surface. The surface of the soil in the area used 
for these experiments was kept well cracked. In no instance did the 
20 outside vines become infested. 
In 1915, field experiments were conducted in a vineyard which 
had several large phylloxera " spots " both on light and heavy soils. 
The light soil might be described as a silt loam with a clay admix- 
ture, and the heavy soil was black, sticky clay. In spring a number 
of sound rooted vinifera vines 1 year old were procured and planted 
in 5-gallon kerosene cans from which one side had been cut. Differ- 
ent types of soil were used in these cans. The vines thus planted 
were kept apart until July, when they were carried out to the vine- 
yard selected and planted level with the soil at varying distances 
from vineyard vines from which wandering larvae were known to 
be issuing. To insure cracking of the soil, water was applied to 
the soil surface and also to the soil between the cans and the near-by 
vine. Wandering larvae were observed in this vineyard from the 
middle of July to August 20. In September, after the wandering 
of the larvae had ceased, the cans were dug up. Table XXXV gives 
the results of this experiment. 
