ANTHRACNOSE OF CUCURBITS. Al 
previous test, only negative results were obtained. Owing to the 
ravages of mosaic, field 2 was becoming unsuitable for work on 
anthracnose and field 1 offered better possibilities. 
- Taste IV.—Anthracnose dissemination test by spraying potted cnciben plants with 
drainage water from water traps. 
Serialnum-| Number of Serial num- Neel of 
bers of pots | anthracnose bers of pots anthracnose 
Trap. sprayed on| lesions on Trap. sprayed on| lesions on 
Sept. 5. Sept. 14. Sept. 5. Sept. 14. 
139 None. 136 5 
IN eae ai { 148 None. || No. 3---------+----+-+-+-- { 137 None. 
145 140 7 
NOEs eee { 146 | NO a aati ae { 138 6 
On September 12 four water traps (5, 6, 7, and 8), similar to those 
in field 2, were placed in field 1 along the extreme western edge and 
at the foot of the slope. The location of these is shown in figure 14. 
The same day a rain of 0.66 inch occurred and the contents of these 
traps were collected immediately afterwards.’ Using the method 
outlined above, dilutions were made from three of the samples and 
a series of seven plates poured in each case. No anthracnose colonies 
appeared in the plates from traps 5 and 7, but in the series from 
trap 6 two colonies of the anthracnose fungus appeared. According 
to the dilution used, this result indicates a spore content of 916 per 
c. ¢. in the water in trap 6. 
The liquid collected from these traps was also sprinkled on healthy 
potted plants in the greenhouse. Seven pots were thus inoculated, 
and on September 19 the plants in each pot were diseased. Each 
sample produced anthracnose infection, and it is quite evident that 
spores were present in the drainage water caught in each trap. It 
is also apparent that this method is superior to the poured-plate 
method for detecting the presence of the spores in such an inoculum. 
These experimental tests prove conclusively that which the ob- 
servational evidence indicated, namely, that the spores are carried 
through the fields by surface drainage water during rains. As to 
the distance carried, recovery of the fungus from these traps along 
the edge of the field indicates that the spores were transported at 
least as far as the extremities of the field in question, and there is 
no reason to suppose that they might not be carried much farther. 
However, the main importance attached to this agency is that it 
serves to disperse the fungus far and wide through the particular 
field already containing original centers of infection. 
Water, then, is not only necessary for the germination of the spores, 
but is also essential to the separation of the spores from the lesion. 
In the shape of rain, it washes the spores to the soil and spatters 
them on to the host plants. In the shape of surface run-off, it dis- 
1 These traps were placed and the contents collected by Dr. E. Carsner. 
