PAPERS ON BOTANY 161 



fruit is one quarter grown. Stevens (1910) urges the 

 adoption of a regular spray schedule of six applications, 

 using Bordeaux mixture. 



It may sometimes be necessary, in severe cases, aug- 

 mented by rainy weather in late summer, to make more 

 than the usual number of fungicidal applications. Wil- 

 cox (1905) believes that control of sooty blotch will be 

 insured by spraying against apple scab, supplemented 

 by one or more applications in July, a progTam also 

 urged by Rolfs (1907). Howitt and Caesar (1917) rec- 

 ommend the application of the regular scab sprays early 

 in the season, using lime sulfur as the fungicide. These 

 are to be followed by an early August application, es- 

 pecially for sooty blotch control. Coons and Nelson 

 (1918) state that it is often the practice in Michigan to 

 use Bordeaux mixture late in July or up to the middle 

 of August, as a supplement to the regular lime sulfur 

 sprays. 



It is worthy of note in this connection that Clinton and 

 Britton (1912), and Blair et al (1916), have found arse- 

 nate of lead to be of some fungicidal value, since it is 

 slightly etfective in sooty blotch control. 



Some work has recently been done with a view to 

 testing the relative effectiveness of the two standard 

 fungicides, lime sulfur and Bordeaux mixture, in the 

 control of sooty blotch. Ballon (1912) states that in Ohio 

 the trouble was thoroughly controlled with one applica- 

 tion of lime sulfur, the spraying being done late in 

 July. He also shows that this material was as effective 

 as Bordeaux mixture. Blair et al. (1916) report Bor- 

 deaux mixture superior to lime sulfur. They show in 

 addition, that lime sulfur ^^-ith arsenate of lead added, 

 was slightly superior to lime sulfur alone, but adding 

 arsenate of lead to Bordeaux mixture did not increase its 

 fungicidal effect. Pickett et al (1918) state that both 

 Bordeaux mixture and lime sulfur, when used separately, 

 completely controlled sooty blotch in 1913 and 1914, while 

 as high as 25 /^ infection was found in the check plots. 



