206 INJUklOUS IN^^ECTS ANi) FUNGI. [Dec 1894. 



Another Potato Fungus (Macrosporiiim solani). 

 Fig. 1. 



Potato Leaf, under surface, attacked by Macroapor'mm solani, natural size. 



This fungus is not distinguished by casual observers from the 

 ordinary potato fungus known as Phytophtkora infestans, 

 although, even to the naked eye, it is quite different in 

 appearance. With a microscope it is readily seen that the two 

 fungi are entirely distinct, and their action upon the potato 

 plant differs also in many important respects. 



The Phytophtkora ravages the leaves and the stems, causing 

 them to rot and decay, and finally descends to the tubers. The 

 Macrosporium attacks the leaves and the stems extensively, but 

 there is an absence of the rapid decay and stench which are so 

 noticeable in the case of potato plants virulently attacked by 

 the Phytophtkora. 



The Macrosporium spreads over the surfaces of the leaves and 

 ultimately destroys them, making them shrivel up and thereby 

 depriving the stems of the power to obtain supplies of food, so 

 that the crop of tubers is small and of poor quality. This 

 fungus does not descend to the tubers, in which no traces of the 

 disease are to be found. 



Potato plants were noticed early in August last to be attacked, 

 as it was supposed, by Phytopkthora infestans, but, as the symp- 

 toms were peculiar, they were closely watched. In time, the leaves 

 dried up completely and fell from the stems, which remained 

 standing upright for some time, though they colla])sed when 

 they lost their greenness, which happened in a few days and some 

 weeks before the proper time. There were patches of the 

 fungus upon the stems, but it is believed that their premature 

 decay was due as much to the loss of their leaves a^ tQ direct 



