CHERRY DISEASES 179 



from the hyphge and penetrate the outer cells of the leaf or 

 twig. As development of the fungus proceeds, conidiophores 

 grow erect and bear chains of conidia. These spores in mass 

 give the powdery aspect to the lesions. At maturity the conidia 

 are carried by the wind to other leaves and twigs, where new 

 infections are initiated. Later in the summer perithecia begin 

 to develop. These are yellowish at first, later brownish, and 

 finally black. When mature, each perithecium contains a 

 single ascus, which contains eight ascospores. 

 % Control. 



The application of some standard fungicide is an efficient 

 remedy for powdery-mildew of the cherry. It is recommended 

 that the orchard be sprayed with bordeaux mixture, or sulfur 

 dust, making the first application as soon as the disease appears. 

 Repeat the application ten days later, if necessary. Sulfur 

 dust may also be used with good success in the orchard. Sulfur 

 is preferable in the nursery. Lime-sulfur 1 to 50 applied as 

 directed for the orchard has proved satisfactory. Add 3 pounds 

 of iron-sulfate to each 50 gallons of the spray mixture; this 

 procedure increases adhesiveness and decreases the caustic 

 qualities of the fungicide. Sulfur dust 90 parts, and powdered 

 lead 10 parts, has proved satisfactory and effective, and may be 

 substituted for lime-sulfur solution. Applications subsequent 

 to the first may number two to four, depending on the severity 

 of the disease. As a rule the schedule for the control of cherry 

 leaf -blight keeps mildew under control (see page 175). 



REFERENCES 



Stewart, V. B. Some important leaf diseases of nursery stock. 



Powdery mildew of cherry. Cornell Univ. Agr. Exp. Sta. Bui. 



358 : 192-194. 1915. 

 Galloway, B. T. The powdery mildew of the cherry. U. S. Agr. 



Comm. Kept. 1888 : 352-357. 1889. 

 Hein, W. H. Two prevalent cherry diseases. Powdery mildew. 



Nebraska Insect Pest and PL Dis. Bur. Bot. Div. Circ. 2 : 1-2. 



1908. 



