108 MASS. EXPERIMENT STATION BULLETIN 192. 



Tests were made in both 1917 and 1918 to determine the effect of 

 Black-Leaf 40 on cranberry diseases. This was used at the rate of 1 part 

 to 400 parts of water, and 2 pounds of resin fish-oil soap to 50 gallons 

 were added. The fruit was picked, stored and examined in the same 

 way as that from the arsenate of lead plots. No positive effect of this 

 treatment on the quality of the fruit was shown by the experiments. 



The "rose bloom" disease caused by Exobasidumi oxycocci Rostr. was 

 prevalent, and deformed many of the blossoms on several bogs in both 

 1917 and 1918, doing more harm than in any year since 1907, and greatly 

 reducing the crop wherever abundant. It affected late varieties mostly, 

 harming Early Black vines on only a few bogs. In 1917 nearly all the 

 new shoots on large portions of the Howes sections of the station bog 

 showed the abnormal enlargement caused by the disease. These growths 

 were first seen the latter part of Maj^, and were present in full develop- 

 ment and abundance until the bog was flowed for worms the night of 

 June 22. When the bog was examined again at 6 p.m. on June 25 (after 

 the water was let off), all the "rose blooms" had turned black and shriveled 

 so much they could hardly be found. The forty-six-hour flooding and 

 the subsequent drying of the vines by strong sunlight had killed the 

 diseased shoots on all parts of the bog. 



The station bog was flowed from Sept. 29 to Oct. 13, 1917, and was 

 flowed for the winter on December 13. The winter water was let off 

 April 4, 1918. In 1918 the "rose bloom" growths were somewhat less 

 abundant on this bog than in 1917, but the disease destroyed most of the 

 crop on two sections. The 1918 growing season was quite drj', but the 

 disease deformed many blossoms. 



In 1918 spraying tests with Scalecide and resin fish-oil soap to kill the 

 "rose bloom" shoots were tried, as follows: — 



1. One gallon to 25 of water with one-half pound of soap applied May 29. This 

 killed most of the "rose bloom" shoots, but left a considerable percentage. It 

 destroyed most of the prospective cranberry bloom, but did not kill the tips of 

 the growing uprights. 



2. One gallon to 37^ of water with three-fourths pound of soap applied May 

 29. This failed to kill a large percentage of the diseased shoots. It destroyed 

 most of the pi'ospective cranberry bloom, but did not kill the tips of the growing 

 uprights. 



3. One gallon to 50 of water with 1 pound of soap applied May 29. This failed 

 to kill a large proportion of the diseased shoots. It destroyed most of the pro- 

 spective bloom. 



4. One gallon to 100 of water with 2 pounds of soap applied May 29. This 

 affected the buds and diseased shoots but little. 



On the whole, these tests were of little value. 



Spraying with iron sulfate to kill the diseased growths was also tried 

 in 1918, as follows: — 



1. Three pounds in 12 gallons of water applied June 1. This killed the diseased 

 shoots fairly well and injured the cranberry uprights but little. 



