OIDIUM OR POWDERY MILDEW OF THE VINE. 339 



The above estimates are based on the tests made, tests which 

 proved effective in completely controlling the disease. The amounts 

 indicated for an acre when the European machine is used are less than 

 is recommended by the best authorities in the south of France. Viala 

 in ' ' Les Maladies de la Vigne ' ' gives 15-30-40 kilos as the amounts to 

 be used for the three sulfurings of an hectare. This corresponds to 

 about 75 pounds to the acre. The vines in the south of France, how- 

 ever, are planted much closer than ours, usually about 1,800 to the 

 acre. The amount for 500 vines therefore would be a little less than 

 our tests indicate. 



Cost of Treatment. The total cost for sulfur ing, including mate- 

 rial and labor, will vary, if the best hand machine is used, from about 

 50 cents per acre for one treatment in the interior to $1.25 for three 

 treatments in the coast valleys, or $2 to $2.25 for five treatments in the 

 most affected localities. 



Power and Traction Machines. No machines of this description 

 have been tested by the Experiment Station for the sulfuring of vines. 

 In Europe it is only lately that they have been used at all. The diffi- 

 culties attending the distribution of large quantities of sulfur in a fine 

 cloud by means of a current of air are very great. It is claimed by the 

 manufacturers of several machines that these difficulties have been 

 overcome, but the machines are very costly. 



Moreover, it is hard to conceive of a machine which would do the 

 work effectively without wasting a large part of the sulfur. When the 

 vines are small, if the sulfur were thrown over a large area, as much 

 would go on the ground as on the vines. As the vines when they first 

 start cover only from 5 per cent, to 10 per cent, of the area, the amount 

 of sulfur used by the power machine would be from ten to twenty times 

 times as much as is necessary. As the cost of sulfur and of labor are 

 epproximately equal with the best knapsack machine, no saving in cost 

 of labor would offset this waste of sulfur. 



When the vines are large it is doubtful whether any machine could 

 throw the sulfur as effectively into the interior of the vine where it is 

 most needed as can be done with the tube of a knapsack machine. 



There is one consideration which makes it seem possible, however, 

 that an effective power machine might have its uses here. There is 

 nothing more expensive than losing the crop, and a power machine 

 might make it possible to sulfur a vineyard and save the crop when it 

 was impossible to have the work done by hand. Even at an extra cost 

 of several dollars per acre this of course would be an advantage. 



Quality of Sulfur. Any kind of sulfur in the condition of a pow- 



