SPECIAL REPORT FOR YEAR I912. 47 



case of forms which cause disease in plants. In some cases 

 the occurrence of a form on a certain host plant has led to its 

 being described as a new species, whereas the same form had 

 already been described on another host under a different name. 

 In such cases where one species can cause disease in two or 

 more hosts it is of great importance to know that it is the same 

 fungus which causes the diseases because that knowledge deter- 

 mines largely whether one of the plants can be used to follow 

 the other in a rotation or whether two or more such host plants 

 can be grown near together. It will be seen that a knowledge 

 of the effect of such a species on its hosts may become of great 

 practical value. 



On account of the lack of knowledge in regard to diseases 

 of plants which are caused by species of this genus in Maine, 

 studies have been made of Fusarium forms which have been 

 found in connection with diseased conditions in a number of 

 plants which are of economic importance. This work was 

 begun in 1908 when 3 species of Fusarium were isolated from 

 decaying apples and it was found by inoculation experiments 

 that each of these was capable of causing decay of apple fruit. 

 Since no species of Fusarium had been reported as a cause of 

 apple decay in America it was decided to study these forms 

 carefully for comparison with a species which had been de- 

 scribed in Europe as a cause of apple decay. One of the 

 Maine forms has been found to agree closely with this fungus. 

 Fusarium forms have been isolated from apples a number of 

 times since but in each case the characters of the fungus have 

 agreed with those of one or the other of the forms isolated in 

 1908. 



In connection with the study of one of the forms from apple 

 it was found that a very similar fungus has been described in 

 other places as the cause of a bud-rot of carnation. The apple 

 fungus was tested by making inoculations of carnation buds and 

 was found to cause the rot. Since that time a fungus similar 

 to, if not identical with, the carnation bud-rot fungus has been 

 isolated from diseased parts of the following plants : Potato, 

 sunflower, sweet corn, and the culms of five grasses which had 

 been injured by the grass thrips. All of these fungi have been 

 grown under the same conditions as the apple fungus for com- 

 parison and all have been tested by means of inoculations on 



