406 Report op the Mycologist of the 



easy to obtain a Petri-dish culture wbieli is almost entirely free 

 from foreign germs. This can be done with small plants but it 

 is more easily accomplished if the plants are large and have well- 

 developed stems. Unless there is an undue amount of moisture 

 on the surface of the medium the colonies show no tendency to 

 spread and run together. 



INOCULATION EXPERIMENTS. 



Attempts to inoculate field-grown plants of sweet corn have 

 been unsatisfactory because it has been practicably impossible 

 to obtain plants which were known to be free from the disease. 

 Susceptible varieties have been quite generally affected, and since 

 the disease is one which acts slowly it is not possible to get 

 results of much value from inoculation experiments made upon 

 plants among which the disease previously existed, even to a 

 slight extent. Only one of the field experiments is worth report- 

 ing in detail. It is as follows: In 189G thirteen hills of Man- 

 hattan sweet corn were planted in one row. In each of the first 

 seven hills there was placed, at time of planting, a handful of 

 dirt taken from soil in which the disease was prevalent the pre- 

 ceding season. The remaining six hills were left untreated for 

 comparison. When the plants were a few inches high they were 

 thinned to four in a hill. A few of the plants in the inoculated 

 hills began to wither before they were a foot high and from this 

 time on they withered one by one^ until on July 20th, when the 

 kernels were " in the milk," all of the inoculated plants except 

 two were either dead or dying. At this date, not a single plant 

 in any of the uniuoculated hills showed any symptoms of the 

 disease; but later in the season several of the plants became 

 affected. How they came to be affected is not known. While 

 this experiment was not wholly satisfactory the results tend to 

 show that the disease is communicable. 



Several attempts were made to inoculate sweet corn by punc- 

 turing the stem near the ground and inserting a small quantity 

 of the diseased tissue of an affected plant. In some of the large 

 varieties the inoculated plants remained healthy to the end of 



