ACCIDENTS, DISEASES, PARASITES. 177 



germinating power ; they have been found in sheep's excre- 

 ment, and, after passing through the digestive organs of 

 these animals, do not seem to lose their vitality ; finally, 

 some have germinated after having been preserved for over 

 a year. This remarkable vitality is one of the great obstacles 

 against the efforts made to combat mildew* 



MEANS RECOMMENDED TO COMBAT MILDEW. 



None of the curative means used so far have given any 

 results against mildew ; these failures are not surprising if 

 we remember that the mycelium of this cryptogam offers 

 very great resistance to the action of outside agencies, and 

 further, it is difficult to reach it inside the leaf, where it is 

 spread, without destroying the leaf. Experiments have, 

 therefore, been made with the object of finding preventive 

 remedies. The following were at first recommended : 



(a) Use of cepages resisting mildew. The first means pro- 

 posed was to plant or graft only ce*pages resisting mildew, 

 amongst which the following attracted the attention of vine- 

 growers Persan or Etraire de VAdui, Durif, Grapput of 

 Dordogne or Prolongeau, Pignon of Me"doc or Pardotte, 

 Sauvignon, Semillon, &c., amongst V. Vinifera ; and CyntJri- 

 ana, Elvira, Noah, Montefiore, Missouri-Riesling, Herbe- 

 mont, amongst Americans. 



Unfortunately, the resistance of these different cepages to 

 mildew is not constant ; it varies with the year. It probably 

 depends on the state of the tissues of the leaf at the time the 

 disease appears ; the above-mentioned cepages, although 

 suffering less than others from this parasite may, however, 

 be attacked by it. Further, the use of such means is only 

 possible for new plantations ; even in this case it has the dis- 

 advantage of restricting the choice of types to be multiplied. 



(b) Use of copper salts. Since the invasion of mildew in 

 the Gironde, it was noticed that vines planted on the side of 

 roads, where it was the custom to spray the grapes with a 

 mixture of lime and Paris green, or lime and blue-stone, to 

 prevent them being stolen, preserved all their leaves perfectly, 

 while those further from the road which had not been thus 

 treated, lost them when attacked by the disease. This treat- 

 ment was, therefore, applied to whole vineyards, and the results 



* The above remarks have been extracted for the greater part from G. Foe'x and P. Viala, 

 Le Mildiou ou Peronospora de la vigne. Montpellier, 1884. 



10890. M 



