INSECTS, DISEASES AND OTHER PESTS 25 I 



CARNATION " SPOT " (SEPTORIA DIANTHi) (deSM.) 



Like rust this spot disease has been known a long 

 time and is widely distributed. Inquiries show that at 

 times it causes considerable damage. The " spot " is 

 characterized by an oblong to circular brownish center, 

 bordered by a purple band. The band is usually well 

 defined near the center, but its outer edge diffuses with 

 the green of the leaf. The whitish to brownish center 

 is usually dotted with small minute black spots. These 

 are parts of the fruiting bodies that produce the spores. 

 The disease is particularly abundant upon the lower portion 

 of the leaves and the internodes of the Carnation. The 

 diseased leaves curl up or become distorted. This disease 

 can be controlled by growing the plants under the best 

 cultural conditions, paying especial attention to ventilation 

 and watering. 



CARNATION RUST (UROMYCES CARYOPHYLLINUS) (SCHRK.) 



A number of years ago Carnation rust was one of the 

 most serious diseases of Carnation plants. Today, although 

 it is present to some extent, one need not be alarmed when 

 it appears in the greenhouse. The decrease in virulence 

 is due in part to the selection of resistant varieties. It 

 was early seen in a study of this disease that some varieties 

 were more susceptible under the same conditions than 

 others. This gave some of the growers an excellent oppor- 

 tunity for the selection of resistant varieties, so that now 

 we have plants that when grown under normal greenhouse 

 conditions will be very resistant to rust. However, these 

 same plants when grown under unfavorable conditions will 

 be very susceptible to rust, so that in the control of rust, 

 normal cultural conditions are necessary. 



