120 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 



pest on cuttings, for these never carry the root form. As their absence, 

 however, is not proved anywhere, and as cuttings may come from 

 regions where they do exist, it is the part of wisdom to disinfect all 

 cuttings before planting. 



Disinfection of Cuttings. The easiest and most effective method 

 for the use of the grape-grower is by means of bisulfid of carbon. 



The method of using the bisulfid is as follows: Place the cuttings 

 in a barrel or vat or a box made tight by means of a thick coat of 

 paint or of paper pasted on the inside. On top of the cuttings place 

 a saucer or other shallow dish, into which to pour the bisulfid of 

 carbon. An ordinary saucer will hold enough for a box of 27 cubic feet 

 or a 200-gallon vat. For larger receptacles it is better to use two 

 or more saucers. Deeper vessels will not do, as the evaporation is not 

 sufficiently rapid. After pouring the bisulfid into the saucer, cover 

 the box with an oiled canvas sheet or other tight-fitting cover, and 

 allow to stand for from forty-five to ninety minutes. At the end 

 of this time there should be a little of the bisulfid left. If it has all 

 evaporated this is proof that insufficient was used. No flame lights 

 should be used, as the liquid burns easily and the fumes form an 

 explosive mixture with the air. Lately, in Switzerland, a cellar was 

 wrecked and a man killed by an explosion of vapors of bisulfid owing 

 to a neglect of this precaution. Care should be taken not to spill any 

 of the liquid on the cuttings, as it may kill them. It is advisable to 

 cut off about half an inch of the lower end of the treated cuttings 

 before planting, as the vapor injures the open pith. 



Besides disinfecting the cuttings in this way, all the packing material 

 in which they come should be burnt, or, if valuable, dipped in boiling 

 water. Practically, it is impossible to disinfect rooted cuttings by this 

 means satisfactorily on account of the difficulty of killing all the 

 Phylloxera without seriously injuring the vine roots. 



Disinfection of Roots. For the disinfection of rooted vines dipping 

 in hot water is recommended by the best European authorities. The 

 roots should remain in water at 125F. to 130F. for ten minutes. 

 The same treatment may be used. for cuttings. The method has several 

 inconveniences, however. Only small quantities can be disinfected at 

 one time, and it requires great care to see that, on the one hand, the 

 heating is sufficient to kill the insects, and, on the other, not sufficient to 

 injure the vines. Experiments with this method by the University 

 are not promising, and many of the rooted vines were killed. 



It is probable that disinfection by means of hydrocyanic gas as 

 practiced for nursery stock would be effective, but data is lacking on 

 this point. 



