206 MANUAL OF MODERN VITICULTURE. 



(B.) Influence of soil. Compact soils with an impermeable 

 subsoil do not require such long submersion and such a large 

 amount of water as those having a certain permeability and 

 resting on a pebbly subsoil. As a matter of fact, the former 

 get rid of the air they contain quicker than the latter, and, 

 therefore, the insect dies sooner. 



(C.) Influence of season. The season has also an influence 

 on the duration of the operation, for phylloxera, as we have 

 already seen, is more sensitive to the action of water when 

 its life is most active. In autumn it is still laying eggs in 

 the southern climates, and will therefore be killed quicker 

 than in winter, when it is in a state of complete torpor. 

 Therefore the submersion must last 35 to 40 days in autumn, 

 and 40 to 50 in winter. 



To sum up, the duration of submersion is, acccording to 

 circumstances, from 30 to 60 days. A depth of 8 to 10 inches 

 of water should cover the whole surface of the soil throughout 

 the operation. A large number of failures, or accidents, 

 resulted from not following the above rule, which had been 

 pointed out from the very beginning by Faucon;* the slightest 

 interruption is sufficient to allow air to penetrate in the soil, 

 and enable the phylloxera to prolong its existence until the 

 operation is finished. 



One should, therefore, always ascertain before starting 

 submerging that the water course or channel will be able to- 

 furnish water at a regular and even rate during the whole 

 operation. 



3RD. AGE AT WHICH VINES MAY BE SUBMERGED. 

 When new vines are planted in soil, or near vineyards 

 already attacked by phylloxera, they should be submerged as- 

 early as possible during the first year, or better, the land 

 should be inundated before plantation, so as to destroy the- 

 insect, which would attack a large number of young plants 

 as soon as they throw roots, and would cause great damage. 

 When, on the contrary, vines are planted in soils free from 

 phylloxera, it is preferable to wait until the second year. 

 A careful examination of the roots, however, will help to fix 

 the date at which the first operation should be performed; 

 one must start without hesitation, directly the slightest 

 indication of the disease is detected. 



* In work mentioned above. [Trans.] 



