FUSARIUM ROT. 



Work on the tomato fruit rot was begun by the writer in the spring 

 of 1902. A diseased condition of the fruit was observed at once on 

 the maturing of the crop, the appearance of which agreed in a gen- 

 eral way with that of Galloway 1 and Whitehead 2 , previously 

 quoted. The spot was always around or at one side of, and contin- 

 gent with the style, slightly sunken, with regular boundary, and 

 clearly defined by a slightly raised ridge, beyond which the tomato 

 was perfectly healthy. The tissue was dry and leathery, a light 

 greyish brown, showing more or less of the shriveled vascular bun- 

 dles beneath. On the larger spots rings of a darker color were 

 sometimes barely visible near the boundary. Small, dark spots were 

 sometimes present on the rotten area. The longitudinal section 

 through a spot showed the interior boundary to be as clearly defined 

 as the outer. The depth of the rotten area was about equal to the 

 surface radius in the most extreme cases, and often extended not 

 more than half that distance. 



A microscopic examination of the spot showed nothing which 

 could be distinguished as a fungus until a careful search had been 

 made. The tissue was dry and blackened, the cells disintegrated. 

 Finally a small tuft of delicate, colorless, mycelial threads was ob- 

 served along the inner border, and by careful searching this charac- 

 teristic form was found in every spot, most easily at the interior 

 margin of the rot. The tufts protrude from intercellular spaces be- 

 tween the blackened walls into the still healthy tissue. (See Fig. 2.) 

 Tufts were also found in the interior of the rot, but in most cases 

 were shriveled beyond recognition. 



A study of the spots on ripe fruit showed the same characteristics 

 as on the green fruit, but it was found that some of the large starch 

 grains so abundant in the green fruit had been retained in the cells, 

 while the healthy tissue, as usual, gave no reaction with iodine for starch. 



Particular attention was paid throughout to the detection of any 

 bacteria which might be connected with the disease. The spot, when 

 first opened, was in all cases perfectly dry and apparently free from 

 bacteria. After remaining in a moist chamber for a day or two, a 

 dense growth of Fusarium developed on the cut surface, often accom- 

 panied by putrefactive bacteria. Repeated attempts to inocculate 

 with these bacteria failed, and several attempts to obtain cultures 

 from the fresh spot were unsuccessful. 



