104 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 



should be kept continuously at a depth of at least six inches until all 

 the insects are destroyed. The best time to do this is in May or June, 

 as at that time four weeks of continuous flooding is sufficient to kill 

 both insects and roots. It is important that every root should be killed 

 in order that, if any insect survives the flooding, it will die for lack of 

 food. Where flooding is impracticable, the vines should be grubbed 

 out and burned in the same way, and the ground kept clean of all 

 growth for at least one year. This is in order that any suckers which 

 may come up from the roots may be destroyed immediately. If crops, 

 or even weeds, are allowed to grow, some of these suckers may escape 

 observation and keep the insects alive to spread the pest the next 

 year. If the affected spot is not too large it is well to disinfect the soil 

 with bisulfid of carbon. This is applied by pouring one ounce each 

 into holes placed two feet apart all over the land to be treated. These 

 holes should be about one foot deep and can be made with a small 

 crowbar or dibble. After pouring in the liquid, the hole should be 

 closed by pressing the earth into it with the foot. 



If, however, the pest has obtained a foothold in several vineyards of 

 the district, or in a large vineyard, it is practically hopeless to attempt 

 to eradicate it. In this case all we can reasonably hope to do is to delay 

 the spread of the pest as much as possible, and in the meantime to place 

 all new vineyards on a permanently phylloxera-resistant basis. Every 

 infested spot in the district should be diligently sought out and treated. 

 The treatment consists in digging up and burning every vine in each 

 spot which shows symptoms of attack, together with at least three rows 

 of apparently healthy vines surrounding them. Disinfection of the 

 soil of these spots by flooding or with bisulfid of carbon is then advisable 

 wherever practicable, but in any case these spots should be strictly 

 isolated in all farming operations. In cultivating the healthy parts 

 of the vineyard, to pass through the infested spots with plows or hoes 

 is a most effective method of accelerating the spread of the insect. 



The search for infested spots is most easily and thoroughly done in 

 July, or August, as at that time the shortness of growth in the " oil- 

 spots ' ' is most readily detected and the insects are easily found, as they 

 are in large numbers on the surface roots and generally also on the 

 trunk of the vine just below the surface of the soil. The search for and 

 destruction of infested spots should be .repeated every year; and if 

 commenced in the early stages of infestation and prosecuted with 

 sufficient thoroughness in every vineyard throughout a district, will 

 effectually prolong the life of the bulk of the vines for many years. 

 As soon as the actual presence of the phylloxera in a district is known 

 and all hope of permanently eradicating it is abandoned, the embargo 

 should be modified to the extent of admitting vine cuttings. These 



