124 



FUXGI AXD FUNGICIDES 



drouth. Black specks develop on the surface of the 

 injured areas^ giving it a granular appearance. These 

 specks consist of the fruiting spores of the fungus. The 

 young seed-pods are sometimes affected. 



If one of the little black specks be looked at from 

 the side under a high power of the microscope it will be 

 seen to resemble Fig. 54^ which represents a tuft of 

 fruiting threads after they have burst through the skin 

 of the leaf. At a is seen a spore borne on the summit 

 of one of these fruiting threads {h, h)^ while at e is seen 

 a spore in process of germination. 



Treatment. — Mr. D. G. Fairchild made some ex- 

 periments in spraying the young plants with the Bor- 

 deaux mixture^, from which he concluded that if the 

 young i^lants are carefully sprayed with the Bordeaux 

 mixture the trouble may be avoided. The spraving 

 should be repeated whenever the spots begin to show. 



Literature. — The only xlmerican articles of im- 

 portance known to me are one by Professor A. B. Sey- 

 mour in The American Florist for September, 1887 

 (p. 38), and another by Mr. D. G. Fairchild, from 

 which the above quotation is made, in the report of the 

 United States Department of Agriculture for 1889 

 (pp. 429-432). 



The Verbena Mildew 



Oidium ei^siphioides 



This often j)i'oves a destructive enemy to verbenas 

 under glass, appearing on the leaves and young stems as 

 patches of white mildew. According to Professor L. H. 

 Bailey, it may be prevented by spraying with sulphide 

 of potassium (one-fourth ounce to a gallon of water) 

 about twice a week. Probably the ammoniacal copper 

 carbonate solution, or other copper fungicides, would 

 prove equally effective. 



