8 BULLETIN 368, U. S. DEPARTMENT OF AGRICULTURE. 
It is evident that spraying is not only of great value in securing a 
yield, but also in the harvesting operations, and that if the fresh 
prunes are to be marketed it is absolutely indispensable. . 
In the summer of 1915 the rainfall at Portland, Oreg., 15 miles © 
distant, was below the average and very decidedly so in March, 
April, and September, the months in which the most critical periods 
of infection apparently occur. It is the number of damp days 
rather than the inches of rainfall that actually determines the oppor- — 
tunity for infection, but in this respect also the season of 1915 was 
not unusually favorable to the disease. It seems probable, therefore, 
that spraying and other remedial measures would be of even greater 
importance in other years than the results in 1915 show for that — 
season. | 
SUMMARY AND CONCLUSION FOR PRUNES. | 
The above observations and results indicate that in such seasons as 
that of 1915 the brown-rot problem is one of great importance to the 
prune industry in the more humid sections of the Northwest. It has 
been shown that the apothecia which develop from the fallen prunes 
are the probable source of the blossom infection. Fall plowing and 
early spring cultivation ahead of the blossoming period have appar- 
ently helped to prevent the disease by interfering with the devel- 
opment of the apothecia. 
The early applications of spray were washed off, showing the 
importance of the addition of a sticker, but even with rather unsatis- 
factory conditions spraying has given fairly good results. The plats 
given both early and late sprayings with self-boiled lime-sulphur set 
from two to five times as much fruit as the unsprayed ones, gave two | 
and a half times as large a yield, and had one-ninth as much brown- 
rot on the harvested and one-eighth as much on the stored prunes. 
Self-boiled lime-sulphur and Bordeaux mixture have both given good 
results, but the former has seemed somewhat more satisfactory. 
Bailey has also reported good results from the use of these fungicides 
on prunes." | 
The sticking and spreading qualities are greatly improved by the 
addition of 2 pounds of resin-fishoil soap to each 50 gallons of the 
mixture. 
Several years’ results will be necessary as a basis for any final 
recommendations, but in so far as the season of 1915 was typical the 
following schedule of spraying may be suggested: 
The first application just before the blossoms open. 
A second just after the petals have fallen. 
A third three to four weeks later, just after the husks have fallen. 
A fourth about four weeks before harvesting. 
1 Bailey, F. D. Experimental spraying of prunes for control of brown-rot. In Oreg. Agr. Exp. Sta., 
2d Bien. Crop Pest and Hort. Rpt. 1913-14, p. 241-244. 1915. : 
