18 



Control (Non IPM) "blocks 

 ,, IPM blocks 



13 



CO 



Eh 



w 



< 

 > 



M 



:=> 

 w 



< 

 CQ 

 O 

 O 



12 



11 



10 



1978 



1979 



1980 



1981 



Figure 2. Trends In the average number of dosage equivalents used in IPM 

 and non- IPM blocks: 1978-1981. 



