ANTHRACNOSE OF CUCURBITS. 57 



treated seed and in three out of the four Wisconsin fields in which the 

 disease occurred might be attributed to overwintering. By this it 

 was meant that the previous crop was grown on the same or a neigh- 

 boring field. Disease conditions in the 1916 crop were in most cases 

 unknown, so it can only be assumed that anthracnose was or at least 

 might have been present. Since treated seed was used, introduction 

 by that means was not at all probable. Of the seven diseased fields 

 in Indiana, four were in cucumbers in 1916 and the other three were 

 adjacent or near the field used in 1916. Of the four diseased fields in 

 Wisconsin, two were in cucumbers in 1916, and in one of these anthrac- 

 nose had occurred that year. Of the remaining two fields, one was 

 not far from the 1916 field in which anthracnose had been very prev- 

 alent. By chance, the owner planted in 1917 one row of treated 

 seed across this field used the previous year. Anthracnose was 

 abundant in this row, while in the 1917 field but one diseased plant 

 was noted. 



The evidence, as summed up in Table VIII for the 75 fields 

 where treated seed was used, shows that 6, or 54.5 per cent, of the 

 11 diseased fields were on the same soil used in 1916 and 4 more were 

 adjacent to the 1916 field, making a total of 10 out of 11, or 90.9 per 

 cent, of the cases of anthracnose possibly attributable to a previous 

 crop. 



Where untreated seed was used the evidence is not quite so con- 

 vincing, but it is rather striking that in Indiana cucumbers had been 

 grown in 1916 in 9 of the 15 infested fields and that two others 

 were adjacent to the field used in 1916. Thus 73.3 per cent of 

 these cases may have been due to a previous crop. 



Another type of evidence is also afforded by the above tests. Of the 

 42 fields in Indiana planted with treated seed, 4 were in cucumbers in 



1916, and anthracnose occurred in all of these in 1917; 4 more were 

 adjacent to the 1916 field, and anthracnose occurred in 3 of these. 

 Similarly, of the 33 fields in Wisconsin planted with treated seed, 3 

 were in cucumbers in 1916, and in 2 of these anthracnose was found in 



1917. Out of a total of 75 fields planted with treated seed, 7 were 

 on the same soil used in 1916, and anthracnose occurred in 6 of these, 

 or in 85 per cent of the cases where rotation was not practiced. In 10 

 fields adjacent to the 1916 sites 4 showed the disease. Likewise, out 

 of 73 fields planted with untreated seed, 14 were on the same sites used 

 in 1916, and in 9 of these, or 64 per cent, anthracnose was found in 

 1917. These results are briefly summarized in Table IX. 



Such observational evidence, especially where the treated seed 

 was used on fields in which the disease was present the year before, 

 practically proves that anthracnose overwinters in the soil. 



Two rather anomalous cases are worthy of note. One is the fail- 

 ure of anthracnose to recur in field 2 at Madison in 1917, The 



