BULLETIN 192. INSECTS INJURIOUS TO THE VINE. 105 



should be introduced, however, under strict quarantine regulations, 

 including disinfection by responsible and properly instructed persons. 

 Rooted vines, or cuttings with pieces of old wood attached, should still 

 be kept out, as they can not be disinfected with any certainty. 



3. However conscientiously and completely these measures are en- 

 forced, a time will arrive sooner or later when the cost of inspection and 

 eradication will be greater than any benefit to be derived from them. 

 We are then face to face with the third set of conditions; we must 

 accept the phylloxera as a permanent inhabitant of the district, and 

 simply consider the best method of growing our vines in spite of its 

 presence. By this time all embargo or quarantine regulations are 

 useless and should be repealed. 



Of the many thousands of methods proposed and tested for maintain- 

 ing a vineyard in spite of the phylloxera, but very few have been of the 

 slightest practical value, and only four are at present used to any 

 important extent. These methods are: 



1. Injection of carbon bisulfid; 



2. Flooding 'or submersion; 



3. Planting in sand; 



4. Planting resistant vines. 



The first two methods aim at destroying the insect; the last two at 

 rendering the vines immune to their attack. As neither of the insecti- 

 cidal methods can be applied with sufficient thoroughness to completely 

 eradicate the pest without also killing the vines, the treatments have to 

 be repeated every year in order to destroy the offspring of the few 

 insects which escaped the treatment of the previous year. For this 

 reason these methods are being abandoned everywhere, especially in all 

 new plantings, in favor of the others, which after the vineyard is prop- 

 erly started, involve no further expense; and as planting in sand is of 

 very limited and local applicability, it may be said that at present the 

 only method that need concern grape-growers in California very seri- 

 ously is the use of resistant vines. 



Bisulfid of Carbon Method. 



Bisulfid of carbon is a liquid which volatilizes very rapidly at ordi- 

 nary temperatures and gives off a poisonous and highly inflammable 

 vapor. This vapor is heavier than air and therefore gradually replaces 

 and saturates the air in the interstices of the soil when the liquid is 

 injected. It is used at the rate of from one hundred and twenty-five 

 pounds to two hundred and fifty pounds per acre, and may be applied 

 at any time except during blossoming and ripening of the fruit. Two 

 treatments, one directly after the vintage and the other a week or so 

 before blossoming, give the best results. The liquid is applied by pour- 

 ing from one-fourth to three-fourths of an ounce into holes made from 



