332 UNIVERSITY OF CALIFORNIA EXPERIMENT STATION. 



current crop, it will injure the buds and canes on which the crop of 

 the following year depends. Moreover, it is this late growth of mildew 

 which produces the winter spores and promotes an early and severe 

 attack of the disease during the following spring. The vines therefore 

 should be kept free from Oidium even if it requires a sulfuring after 

 the grapes are gathered. 



In the coast districts where weather conditions similar to those of 

 Berkeley exist, even three sulfurings will seldom be sufficient to hold 

 the Oidium completely in check. "Where the springs are warm and the 

 summers comparatively cool and moist, as along the coast of Santa 

 Cruz, the fungus finds conditions favorable to its development at all 

 times of the year when the vines are in leaf. In such locations an early 

 sulfuring, when the shoots are 3 or 4 inches long, another at blossoming 

 and a third when the grapes are the size of buckshot are always neces- 

 sary. If these are thorough and there are no neighboring neglected 

 vineyards to spread continuous reinfection, certain varieties may be 

 kept free in good years by three sulfurings. It will, however, usually 

 be necessary to interpolate another treatment between the first and 

 that at blossoming time and follow the third with one or two supple- 

 mentary treatments. 



Sulfuring Young Vines. Young vines, whether in the vineyard or 

 the nursery, should not be neglected. In the nursery they are pecu- 

 liarly susceptible owing to their nearness to each other and to the moist 

 air near the irrigated soil. Autumn sulfuring is nearly always useful 

 in this case to keep the leaves healthy until they have ripened the canes. 

 Young vines during the first year in the vineyard are seldom seriously 

 injured by mildew, but it is advisable to sulfur them at least once dur- 

 ing the early summer. 



Methods of Applying Sulfur. From what has been said of the 

 action of sulfur on the fungus, it is clear that thorough distribution is 

 the main factor in its effective application. Providing we get some 

 sulfur on every part of every vine in the vineyard, the amount we use 

 is of little importance in controlling the disease. 



Whatever the fumes may be which are given off, the amount of 

 sulfur used in producing them is infinitesimal. The smallest quantity 

 of sulfur we can possibly use in practice is amply sufficient if we ac- 

 complish the object of leaving no part of the vine untouched. 



On a properly sulfured vine the distribution is so perfect that on 

 close examination we are unable to find a square inch of surface free 

 from sulfur grains. On the other hand, if on looking at a vine from 

 a distance of twenty feet we can see any signs of the sulfur applied, 

 more than enough has been used. 



