Semi-Centennial Volume. 131 



Physoderma (zeiB-maydis?) in Kansas. 



L. E. MKiit'UKBS. 



The writer collected specimens of Physoderma (zese-viaydis?) on Zea 

 mays at Manhattan, Kan., in October, 1915, in a field of corn which 

 was being used for experimental purposes. Although it was strongly 

 suspected that the fungus was Physoderma, it was not definitely deter- 

 mined until sometime later. Comparing this date of collection with 

 that of other collections made up to that time in the United States, it 

 appeal's that the discovery of this fungus in 1915 made the report the 

 third in the United States. Since then, however, it has been located 

 in numerous other states, particularly since the United States depart- 

 ment of agriculture began its survey of this disease in 1917. 



How long Physoderma has been in Kansas is not known, but the 

 writer believes probably prior to 1913. Its presence in traces could 

 easily escape attention. Its appearance in 1915 attracted notice and 

 numerous collections were made. No specimens were found in 1916, but 

 in 1917 it was again found and collected. It appeared in very limited 

 quantities, at this time in May, in the vicinity of Manhattan, when a 

 few specimens were collected. In October considerable specimens were 

 located in the vicinity of Manhattan. Prof. G. W. Wilson visited Man- 

 hattan in October of 1917, and at that time was connected with a survey 

 of this fungus in the employ of the United States Department of Agri- 

 culture. The writer is indebted to him for much of the data furnished 

 in 1917. Up to the present date, Physoderma has been located in Kansas 

 in the following places: In the Neosho bottoms in the vicinity of Chetopa, 

 particularly to the east in the river bottoms, considerable amounts were 

 located, and this likewise holds true for the lola region. A trace was 

 found at Fort Scott. It also occurred in slight amounts at Garnett, 

 Ottawa and Marysville. At the latter place, one field contained con- 

 siderable of the fungus. In Manhattan, the percentage ran higher than 

 any place in the state as far as known. Here it did not only occur on 

 the leaves and sheaths of the corn plant, but it was actually penetrating 

 the nodes. The vicinities of Parsons, Independence, Lawrence and 

 Emporia were visited, but no trace of the fungus was located. 



The symptoms of the fungus in the early stage are rather difficult to 

 distinguish from injury caused by Aphids. Blackened, irregular spots, 

 or blotches may occur on the sheaths or main ribs of the leaves of the 

 corn plant. Later in the development of the fungus, and as the host 

 matures, these spots begin to rupture and expose a powdery, dark, 

 reddish-brown mass of spores. The ruptures are irregular and may 

 vary from a few to many millimeters in length. A shredded condition 

 at the base of the leaves is not uncommon; in fact, this is one of the 

 striking characteristics of the fungus. When the nodes of the corn 

 plant are attacked and penetrated by this fungus, the infected regions 

 show a more or less shrunken condition. 



