FUNGICIDES 



367 



100 



80 



z 

 o 



I- 

 < 



a. 

 o 



t- 



Z 40 

 O 



cr 



UJ 

 Q. 



20 



10 16 20 24 



MILLIGRAMS SULPHUR PER SLIDE 



32 



100 



T- 



Z 



o 



5 



5 



u 

 O 



z 



u 



u 



cc 



LU 



Q. 



60 



20 



® 



2 8 



32 



NUMBER PARTICLES PER 100 MICRON SQUARE 



Figure 143. (Above) Toxicity curves, for three unmodified sulfur dusts of signifi- 

 cantly differing mean particle size, plotted on a weight basis and showing a significant 

 difference in toxicity. Germination of conidia of Sclerotinia fntdicola. (Below) The three 

 upper curves plotted on the basis of particle numbers become one curve showing that the 

 distribution or number of sulfur*particles determines the toxicity. 



most important copper fungicide. Bordeaux is a complex mixture of copper 

 sulfate and hydrated lime, and despite much research its chemistry is still 

 not entirely understood, though careful work by Martin -^ indicates that it is 

 cupric hydroxide stabilized by adsorbed sulfate ions. The copper is present 



