THE GRAPE PHYLLOXERA IN CALIFORNIA. 121 
danger of phylloxera infestation following the planting of a cutting 
from such wood. This danger does not exist in California, provided 
the cuttings are not " heeled in " before transportation, because the 
winter egg does not persist successfully. If the cuttings are " heeled 
in" before transportation in an infested district, the possibility of 
their becoming phylloxerated exists. Similarly, the possible danger 
from gallicoles remaining upon the foliage of canes late into au- 
tumn is nullified, because the gall-inhabiting forms do not normally 
occur in California. 
The greatest danger of phylloxeration resides in the planting out 
of infested rooted vines. This is a very abundant means of distrib- 
uting phylloxera. Even if only one or two out of a thousand vines 
are infested at planting, a " spot " or " spots " will form within a 
few years, and the whole acreage eventually will become infested. 
While the vines remain small, diffusion is slow because the roots of 
one vine are separated from those of its neighbors, and underground 
diffusion thus- is rare if not impossible. Also, the relatively small 
number of roots, coupled with the relatively small number of phyl- 
loxeras able to flourish thereon, prevents many opportunities for 
aerial diffusion by wanderers. If the majority of the vines planted 
out contain phylloxeras, however, the vineyard's complete phyllox- 
eration is not long removed. In a phylloxerated district the employ- 
ment of resistant roots obviates the necessity of treating the vines 
before planting out in the vineyard, yet danger exists in cases where 
grafted vines are planted too deeply and the stouter vinifera scion 
is enabled to send out its own roots, in many instances crowding out 
the roots of the resistant stock. The scion's roots, being nonresist- 
ant, decay when phylloxerated just as though no resistant stock had 
been employed, and the expense and trouble of the grafting process 
are wasted. Even though phylloxeras live on resistant stock roots 
in grafted vineyards without necessarily injuring the crop or vines, 
there still remains the possibility that infestation will arise from 
these grafted vines and that nongrafted vineyards near by will be- 
come inoculated. Such a possibility is accentuated the greater the 
proximity of two such vine areas, and especially if the nonresistant 
area is to leeward of the grafted area or if water flows from the 
grafted to the nonresistant vineyard. It is advisable, therefore, to 
disinfect even resistant roots when these are to be planted in a region 
free from phylloxera. 
PHYLLOXERATED LAND. 
Experiments with potted vines have given proof that phylloxeras 
may live at least 10 months on buried severed pieces of roots, and 
also that such pieces may remain sound for 18 months and at the 
termination afford acceptable food for the insect. It is evident, there- 
