Ornamental Plants 435 



SPURGE 



Anthracnose (Gloeosporium euphorhice Hal.). — The attack 

 usually begins upon the flower cluster and passes down the 

 stem to the leaves, which then fall away, leaving the naked, 

 blighted branches. The disease often interferes seriously 

 with the ornamental effect of this decorative plant. 



SUNFLOWER, JERUSALEM ARTICHOKE 



Rust {Puccinia helianthi Schw.). — ^ Both wild and cul- 

 tivated species of sunflowers are often badly rusted. The 

 early sori are yellow to brown, the later black. Badly rusted 

 leaves die and much injury follows both to flower and seed. 

 In the spring the cluster-cup stage is sometimes found upon 

 the same host. Burning of infested refuse is the only remedy 

 known. 



j)j.Qp 455 (^Sclerotinia perplexa Law.). — The disease ap- 

 pears first in the root or lower stem and spreads upward to 

 the heads. It in general character resembles lettuce drop. 

 Leaf-spot {Septoria helianthi- E. & K.) is common but not 

 serious. 



SWEET-PEA "^4 



Anthracnose {Glomerella cingulata, Gloeosporium) occurs as 

 spots on stems, leaves, and pods. Seed from diseased pods 

 should be avoided. 



Powdery-mildew (Microsphcera al.ni, Oidium). — This is 

 not usually troublesome if proper greenhouse conditions are 

 maintained. See rose. 



Streak {Bacillus lathyri M. & T.). — Dark streaks occur 

 on the stem. Wilt {Fusariuvi). — See cowpea wilt. Drop 

 (Sclerotinia) . — See lettuce. Mosaic. — See tobacco. Root- 

 rots are numerous, due to Nematodes, Thielavia, Corticium, 

 and other fungi. 



