Resi5tance:6 



TOLERANCE LEVEL OF TOBACCO TO 

 PRATYLENCHUS MINYUS 



NOs PER Grm. OF ROOT 



(THOUSANDS) 



Figiire 5« "Hie dosage-response curves for P, mlnyus. Notice that the 50^ 

 growth reduction value is much lower for Harrow Velvet than for any of the 

 other varieties. We can now measure quantitatively the tolerance to the 

 different varieties. 



TOLERANCE LEVELS OF TOBACCO TO 

 PRATYLENCHUS PENETRANS 



NOs. PER Grm. OF ROOT 



( THOUSANDS} 



Figure 6, The dosage-response curves for P, penetrans . Notice that the 

 50^ growth reduction value is not very mucF different in any variety, i.e., 

 there is not the tolerance there was for P, minyus. 



