A Study of Meadow-Crop Diseases in New York 



95 



An artificial epiphytotic was started June 4 by surrounding each plot with 

 ten pots of severely rusted plants from the greenhouse. The epiphytotic 

 was fairly well established on the check plots by the time the timothy was 

 harvested on July 11. The rust on the dusted plots appeared less abund- 

 ant to the eye at the time. The hay wa? cut just as most of the plants 

 passed the blooming stage. Green weights of the plots are given in table 26. 



TABLE 26. Results of Field Dusting for Timothy Rust 

 (Green weight) 



Observation of the field and of the data as well, reveals that the land 

 increases in fertility towards the south (foot of table 26). The only ade- 

 quate method of calculating the data therefore is by the pairing of con- 

 tiguous east-west plots, which gives a mean difference of 21.5 ± 2.47 which 

 is highly significant. This difference shows a gain of 11.8 per cent by the 

 use of the sulfur dust. These figures agree with the laboratory results. 

 Unfortunately, a lack of adequate facilities for further field work precluded 

 a continuation of these studies in 1928. 



Effect of copper. In the spring of 1927 a great many laboratory tests 

 of copper-lime dust diluted in lime were made. Dusts containing the fol- 

 lowing percentages of metallic copper were used: 6.8, 3.4, 1.7, and 0.34. 

 The data obtained are to be found in table 27. 



