D8 BULLETIN: 727, U. S. DEPARTMENT OF AGRICULTURE. 
other is the fact that in one of the Wisconsin fields, where the disease 
occurred in 1914, 1915, and 1916, no anthracnose could be found in 
1917 when treated seed was used. 
TaBLeE IX.—Relation between lack of crop rotation and the occurrence of cucumber 
anthracnose, season of 1917. 
Fields used for cucumbers in 1916. 
Number of Anthracnose in 1917. 
Seed used. fields. 
Number. 
Percent- 
Number. age. 
Timbre ae Ce eG a nk eee age Zeer 73 14 9 64 
Mreated seo eee Seperate eS a Aho apes MEL eal | 75 7 6 85 
Total Rei eee EET SEE oe REE SEA RS eee ee “21148 21 15 | 71 
As to the mode of overwintering and the possibility of a perfect 
stage nothing definite is known. Using soil collected from a dis- 
eased field in October, Carsner ! secured seedling infection in Febru- 
ary. He also secured seedling infection in sterile soil with which 
were mixed chopped-up diseased vines previously kept in storage 
for five months. Potebnia (38, p. 82) left diseased host parts out of 
doors over winter but failed to find an ascus stage. 
In the fall of 1916 diseased vines and fruits of various hosts were 
placed in wire cages and left on the ground in the garden over winter. 
On April 11, 1917, 14 samples of soil were taken in sterile pots from 
under these cages. ‘Treated seed was planted in these pots, but no 
anthracnose appeared on the seedlings. Examination of some of the 
overwintered material in the cages on March 29 failed to show the 
presence of spores, and no development of the anthracnose fungus 
occurred under damp chamber conditions. More work should be 
done along this line.? 
The present status of the problem is, then, that field observations 
and tests prove that the fungus overwinters in the field, although the 
exact mode of this overwintering is unknown. 
CONTROL. 
Consideration of the control of anthracnose may be conveniently 
divided, so far as this work is concerned, into two categories, spraying 
and seed treatment combined with crop rotation. 
1Carsner, E. Op. cit. 
2In the fall of 1917 diseased cucumber vines were buried in a small flower garden in Lansing, Mich., 
where anthracnose had never been present. In the summer of 1918 treated cucumber seed was planted 
in this spot. On August 4, 37 out of 58 plants were diseased with anthracnose, many damping-off with the 
disease. This proves that the fungus overwinters in the old diseased vines in the soil. Furthermore, 
treated 1916 seed was planted in 1918 in a 2-acre portion of the Michigan seed field which had borne a badly 
diseased crop in 1917. Anthracnose made its appearance at numerous and scattered points in this field 
in 1918, thus further proving that the fungus overwinters in the soil. 
