Uromyces hyalosporus Sawada. sp. nov. 



causing the Disease to the Shoots 



of 



Acacia confusa Merrill. 



by 

 Kaneyoshi Sawada. 



The " Soshiju," Acacia confusa Merrill., is one of the most 

 useful trees in Formosa and is widely planted for avenue, 

 ornamental, fuel, timber, wind-breaker and many other purposes. 

 Any one traveling through the Island would notice the pros- 

 perous afforestations, and the nurseries of this tree in every 

 districts, and also at the same time would be struck with the 

 prevalence of a serious disease due to a rust-fungus especially 

 on the shoots of young trees in the nurseries. 



When badly affected, the uredo-sori occur in great abun- 

 dance, even 50 in number, on a phyllod. They often coales- 

 cence with each other into large patches, deforming ph\ T llods 

 and young twigs, which are thereby interrupted in growth, 

 and are finally killed. On large trees, both pods and phyllods 

 are usually affected. 



The uredo-sori are borne on both sides of a phyllod, where 

 the leaf-tissue bulge out into a wart-like protuberance, concave 

 on the opposite surface. On the convex surface the numberless 

 spores are produced giving a brown powder}^ appearance. 

 The uredo-spores arc fusiform in shape and yellowish to golden- 

 brown in color. 



They measure 30 to 84 u in length and 17 to 27 u in 

 breadth, having equally thickened verruculose epispore, 2—4 // 



