116 MANUAL OF FRUIT DISEASES 
and soon the parasite has extended itself to other twigs and 
leaves in a manner conducive to certain perpetuation. 
Control. 
The application of certain fungicides supplemented by the 
eradication of heavily mildewed twigs are satisfactory remedial 
measures. But the disease is not easy to control. In those 
cases where copper sprays are still in use, little benefit may be 
expected so far as the control of apple powdery-mildew is con- 
cerned. The chief difficulties lie in the fact that copper com- 
pounds produce leaf and fruit injury, and that the mildew fungus 
is not as susceptible to bordeaux mixture and similar copper 
sprays as it is to the sulfur sprays. The sulfur compounds are 
effective under certain conditions of preparation. Sulfur in 
some very finely divided state is the most efficient fungicide 
available for use against this disease. Such fungicides as ground 
sulfur, sulfur flour and flowers of sulfur are all said to be too 
coarse to yield satisfactory results. On the other hand, pre- 
cipitated sulfur is particularly effective against apple powdery- 
mildew. This may be obtained by the use of lime-sulfur solu- 
tion, diluted one gallon of the concentrated solution to fifty 
gallons of water to which is added three pounds of iron-sulfate. 
By stirring the two together a black, muddy precipitate is 
formed ; this contains sulfur in a finely divided condition, iron- 
sulfid and calcium-sulfate. It has been demonstrated that this 
spray is effective against apple-mildew both in New York State 
and in the Pajaro Valley, California. In the nursery the first 
application should be made soon after the seedlings have 
developed the first new shoots. Three or four sprayings should 
follow at intervals of about two weeks. According to experi- 
ence in the Pajaro Valley, orchard trees should be sprayed as 
follows: (1) apply the above fungicide in conjunction with the 
first spraying for codlin-moth ; (2) in conjunction with the second 
application for codlin-moth; (3) three weeks after the second ; 
(4) three weeks after the third. These recommendations, while 
