RUST OF ANTIRRHINUM. 



51 



Table 4. — Relative Susceptihility of Antirrhinum Varictie'^ to P. Antirrhii 



Varieties. 



While. 



i Queen of the Xortli, 

 I 



I Pure \\ hite, . 

 Giant White, 

 Phelp's White, . 

 I Queen Mctoria, 

 [ Mont Blanc, 



Yelloir. 

 Giant Yellow, 

 Hepbaetos, 



Dwarf Golden Queen, 

 Sulphur Yellow, . 



Pink. 

 ! Rose Dore, . 

 ( Bridesmaid, . 



Giant Rose Pink, 



Rosy Morn, . 

 f Nelrose, 

 [ Silver Pink, . 



Dwarf Daphne, 

 f Rose, 

 [ Giant Pink, . 



Dwarf Rose Queen, 



Carter's Pink, 



Delicate Rose, 



Venus, . 



Chamois, 



Scale, 

 Relative 

 Numbers. 





 

 

 

 

 







9 

 100 

 100 





 

 23 

 30 

 51 

 51 

 65 



93 

 100 

 100 

 100 

 100 



Varieties. 



Variegated or Mixed Color 

 Striijed \'ariety, . 

 Bronze Queen, 

 Niabe, 



Fairy Queen, 

 Carter's Gold Crest, 



Red. 

 [ Crimson, 

 I Giant Blood Red. 

 [ Fire Brand, . 



Scarlet, 



Giant Scarlet, 

 f Dwarf Defiance, . 

 [ Giant Garnet, 



Dark Scarlet, 



Half Dwarf Firebrand 



Carter's Butterfly, 



Orange King, 



Black Prince, 



Deep Crimson, 



Coral Red, . 



Ruby, . 



Fiery Belt, . 



Crimson Queen \'ictori 



Scale, 

 Relative 

 Numbers. 



9:5 

 93 

 100 





 9 



16 



23 



23 



37 



44 



51 



58 



58 



79 



86 



100 



100 



100 



Cause of Resistance. 

 Resistance of plants to disease has been explained in two general ways: 

 (1) Resistance may be regarded as being related to certain morphological 

 characteristics. Cobb (1892) considered resistance to fungous disease as 

 being due to small stomata, waxy coating, and thick cuticle on the host. 

 Freeman (1911) found that increase in bloom on barley leaves made 

 the plants more resistant to rust. Valleau (1915) studied resistance 

 of plums to brown rot. and considered resistance to be due to the pro- 



