ANTHRACNOSE OF CUCURBITS. 53 
TasLe VI.—Laboratory tests of seed inoculated with spores of the anthracnose fungus. 
Date of Number 
Hest aaeccd! Medium used. Days. Result. 
Mar. 14 50 Sterile sand, in damp chamber......- 29 | 16 out of 45 seedlings diseased. 
14 28 2 per cent dextrose solution, in filter 14 | Anthracnose detected on five. 
aper. 
15 6 2 per cent dextrose agar.......------- 15 | No.anthracnose. 
23 6 Wiet ail tera pa pei ssee ee ear eer ease 13 | 1 seedling diseased at heel. 
23 6 2 per cent dextrose solution, in filter 17 | No anthracnose. 
paper. 
23 12 Prune decoction, in filter paper... .-. 17 Do. 
23 100+- | Wet filter paper, in damp chamber. - 18 Do. 
As a result of the difficulties encountered and negative results 
secured in the endeavor to prove by laboratory methods the presence 
of the anthracnose fungus on commercial seed, the problem was ap- 
proached in another way. 
FIELD TESTS WITH DISINFECTED SEED. 
Certain theoretical considerations form the basis of this method 
of attack. Since observation indicated that the number of original 
centers per acre was usually rather low, ranging perhaps from 1 to 10, 
and since about 2 pounds, or approximately 70,000 seeds, are used 
per acre, it was to be assumed on the basis of seed carriage of disease 
that not more than 1 to 10 seeds out of 70,000 were acting as suc- 
cessful bearers of the disease. In view of this possibility, the failure 
of the laboratory tests might be attributed in part to the sa 
small numbers of seeds tested. 
To obtain a test with larger numbers of seeds, recourse to field con- 
ditions was necessary. It was obvious that if the fungus could be 
eliminated by surface sterilization of the seed, the appearance of the 
disease in a new field planted with such seed should be prevented, 
while in a field planted with untreated seed the disease would nor- 
mally be expected were the fungus present on the seed. 
As to the character and effect of various seed treatments, more 
will be presented later. Suffice it to state here that the surfaces of 
seeds immersed in mercuric chlorid of a strength of 1 to 1,000 for 5 
minutes were found by agar-plate tests to be sterile. With the other 
dismfectants employed, the effectiveness against the anthracnose 
fungus was assumed. ‘Two classes of tests were made in the season 
of 1917, one limited to a few fields at Madison, the other being more 
extensive. 
At Madison a mixture of 1916 Ohio seed previously tested with a 
new consignment from the same source was tested in four well- 
separated one-half acre fields on soil not previously in cucumbers or 
melons. In one field untreated seed was planted, while in the others 
seed treated as shown in Table VII was used. By planting double 
