234 COLOCASIA BLIGHT. 



grounds, transferred the species to the genus Kawakamia, a genus 

 founded by K. Miyabe for a fungus parasitic on the stems of 

 Cyperus tegetiformis 1 , and itself doubtfully tenable. 



In India the distribution is wide, from Travancore on the 

 south to Dehra Dun and Rangoon on the north and east, and 

 in Bengal it is one of the commonest of the Peronosporacece. It is 

 found everywhere in the plots of kachu (Coloeasia antiquorum 

 Schott.) seen towards the middle of the rains in most villages. It 

 also occurs in the wild specimens of the same plant common in 

 moist localities. Raciborski's statement that it causes little 

 damage is too sweeping. Sometimes, in favourable weather for 

 its development, the leaves are so rotted that the entire plant is 

 killed. In 1909, during a period of almost continuous cloud and 

 rain in August, a number of plants died from the disease at Pusa 

 and the growth of the rest was brought to a standstill. Further, 

 the parasite commonly reaches the corm and sets up a dry rot during 

 storage. This stage was not known to Raciborski but is probably 

 more destructive, as a rule, than the leaf attack. 



The disease first manifests itself ordinarily on the leaf. Small 

 dark roundish specks appear which widen rather rapidly by cen- 

 trifugal growth. The growth may be equal all round, in which 

 case the spot remains circular, or may be more rapid in one direc- 

 tion than another, when we find oval, elongated or irregular patches 

 (PI. I). The main veins of the leaf often check extension for a 

 short time but are soon crossed. Two or more spots may unite 

 and ultimately a very large part of the leaf surface may be involved. 

 In the early stages drops of a clear yellow liquid ooze out from the 

 surface of the spots ; later, the central portion assumes a yellowish- 

 brown colour, dries up and may become perforated. The margins 

 are often beautifully zoned, in different shades of brown, green and 

 yellow ; towards the periphery these zones reveal on careful exam- 

 ination a delicate white haze which is caused by the sporangia 1 

 stage of the fungus. This external development of the parasite is, 



1 Miyabe, K., in Kawakanii, T. " Kawakamia, Miyabe, a new genus belonging to Pero- 

 nosporacece." Tokyo, Shokwabo & Co., 1904. 



