reporting the results of the control studies, it has seemed best to 

 analyze each fungicidal materia] separately as to its effectiveness 



in controlling the disease. 



Needles of trees sprayed with Bordeaux mixture have constantly 

 been found to be heavily infected and appear to be much drier than 

 unsprayed needles during the spring of the year following spray 

 applications. There were certain indications that the fungicide had 

 actually stimulated fungus development on some needles. Infection 

 by R. pseudotsugae was especially heavy on the lower branches of 

 Bordeaux-sprayed trees. Needles of lammas shoots appeared to be as 

 heavily infected as those of spring shoots on some trees. Adventitious 

 buds which developed along the bare twigs of these trees produced 

 needles which also became infected. Generally, the foliage of Bor- 

 deaux-spraved trees appeared to become excessively thin. Indeed, 

 many of the spring-infected needles were cast by March and April 

 of the following year, before apothecial maturation. 



The consistent failure of Bordeaux mixture to give control was 

 unexpected since it has been recommended specifically for the con- 

 trol of the disease by several authors (1, 5, 13, 16, 66, 68). Fischer 

 (16) in Germany, and Weistaner (68) in Montana, reported control 

 with a 4-4-50 concentration similar to that used in the present 

 studies. The subsequent drying of Bordeaux-sprayed infected needles 

 was not mentioned by either investigator. The lack of drying of 

 sprayed young and old non-infected needles leads to the conclusion 

 that the spray stimulated R. pseudotsugae in some manner, thus 

 indirectly causing the more rapid and complete dessication of 

 needles through greater fungal activity. The action by Bordeaux 

 throughout the course of the present study has certainly been incon- 

 sistent with existing reports of its use against R. pseudotsugae and 

 needs further investigation. 



Lime-sulfur gave nearly 100 per cent control at Camden and 

 Cortland, New York, in 1956. A few apothecia developed on scat- 

 tered basal branches but probably as a result of inadequate spray 

 coverage. Control was excellent on early spring needles as well as 

 those of lammas shoots. The lower sprayed portion of such trees 

 made a sharp contrast with the heavily infected unsprayed upper 

 part of the tree. There were no signs of burning of foliage by the 

 use of a seven-tenths per cent water solution of Lime-sulfur. Weis- 

 taner (68) used Lime-sulfur on Rhabdoclinc needle cast in Montana, 

 but it provided no control. He theorized that his solution might 



53 



