BUCKEYE DISEASES 



119 



defoliation results in retanHnc; tlic growth of the trees and 

 making tliem more susceptible to winter-injury. 



Si/mptoms. 



The lesions develop on the leaflets and petiole. AMien 

 first evident, the spots are irregular in outline, slightly dis- 

 colored and water-soaked in appearance. Later the center 

 of the spot becomes red- 



dish brown and is sur- 

 rounded by a yellowish 

 zone which blends into 

 the green of the healthy 

 part of the leaf. Finally, 

 the entire affected area 

 turns brown and becomes 

 dried and brittle (Fig. 14). 

 The spots may be small 

 or may involve large areas 

 and cause a curling of 

 the leaflet. Small black 

 specks, the fruiting-bodies 

 of the pathogene, develop 

 either in the lighter colored 

 center of the brown blotch 

 or may be foimd distrib- 

 uted sparingly over the 

 entire dead area. Small 

 reddish brown lesions are 

 also sometimes formed on 

 the petioles. 



Fil;. 14. — Lcaf-blotcli '->f horse-chestiiut. 



Cause. 



The leaf-blotch of horse-chestnut and buckeye is caused 

 by the fungus Giiignardia ascidi. Fruiting-bodies containing 



