Fungicides 451 



applied just after the petals have fallen, and even the most 

 susceptible varieties become almost completely immune 

 within a period of six or ten weeks after this stage. 



On the fruit, injury is manifested by the formation of small 

 black specks or the surface is russeted, sometimes very 

 severely, and the fruit may be split or otherwise distorted. 

 Injury to the foliage may first appear a few days after spray- 

 ing or may be delayed for several weeks. Brown, dead spots 

 are frequently caused, which may be followed by the yellow- 

 ing and falling of the leaf. Yellowing may occur, however, 

 when no brown spotting is observed. 



Before the discovery of the fungicidal properties of lime- 

 sulfur and its efficiency as an early summer spray, various 

 methods were suggested for the mitigation of Bordeaux in- 

 jury. At present, lime-sulfur has very largely replaced 

 Bordeaux mixture for use in the early summer. 



There are, however, circumstances under which Bordeaux 

 mixture is still used at this season. It is generally conceded 

 that lime-sulfur, applied with sufficient frequency, gives as 

 good control of apple-scab as Bordeaux mixture, but that it 

 is less adhesive and must be applied more frequently. Since 

 the period when the trees are in blossom is sometimes pro- 

 longed by adverse weather conditions, Bordeaux mixture is 

 still consistently used by some fruit growers for the pre- 

 bloom spray, on varieties locally subject to severe injury from 

 scab. Bordeaux mixture may be used for the early blotch 

 sprays on varieties not subject to Bordeaux injury, for all 

 varieties in the control of bitter-rot and blotch after the 

 period of immunity to serious Bordeaux injury has been 

 attained, and of course for the entire program for varieties 

 immune to this form of injury. 



Hedrick ^^^ has published an extensive list of apples classi- 

 fied as to their immunity or susceptibility to Bordeaux in- 

 jury. 



Lime-sulfur injury, ^i^ '^^'^ — Lime-sulfur injures many 

 plants very seriously. Slight injury to the leaves of apples is 

 of common occurrence. It is not usually of great consequence 



