382 



GROWTH OF PLANTS 



30,000 



10,000 



3000 



(0 

 UJ 



-1 

 o 



O 1000 



a: 

 o 



o 



< 



bJ 

 O 



z 

 o 

 o 



300 



100 



30 



10 



r I 1 1 1 1 1 • I f II 



PHYTOTOXICITY- THRESHOLD CONG. 



O Unsaturated 



\ 



-L 



J_ 



9 13 17 21 



SUBSTITUENT CARBON ATOMS IN 2 POSITION 



25 



29 



Figure 152. Comparison of the eflfect of number of carbon atoms in the substituent 

 in the 2-position on fungistatic action and phytotoxicity for the derivatives of hydroxy- 

 ethylglyoxahdine. Note that greatest spread between fungistatic action and phytotoxicity 

 is with 17 carbon atoms. Concentration is expressed as micromols per liter. Phytotoxic 

 values average for tobacco, buckwheat, and bush bean and fungistatic values average 

 for *S. fruciicola, A. solani, G. cingulata, and M. sarcinaeforme. 



