Maya, i 9 2 1 Effect of Ferrous Sulphate on Chlorosis of Conifers 161 



the surfaces of the two plants. Conifers are very difficult to coat evenly 

 with a spray. Also the fact that there had been practically no rain from 

 the first treatment to the time the injury was observed may have been 

 responsible for the degree of injury by the 2 per cent solution. In a 

 region of heavier rainfall this solution, or even a stronger one, might be 

 entirely harmless to conifers. The treatments were continued, but with 

 a i per cent solution at the rate of only o. i of a pint, containing approxi- 

 mately 0.47 gm. of ferrous sulphate per square foot of seed bed. Spray- 

 ings with this weaker solution were made on August 24, September 3, 

 September 12, September 22, and October 2;- and the seedlings on sample 

 areas were counted and classified as to the degree of chlorosis on different 

 dates in September and October, and again in April of the following year. 



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FlG. 2. Graph showing the effect of a ferrous sulphate spray treatment on chlorosis in seedlings of western 



yellow pine 2 to 5 months old. 



The results are shown graphically in figure i. Decided inprovement in 

 the color of the sprayed plots during the period covered by the counts 

 is indicated by the data. The undiminished persistence of the good 

 effect through the winter, a total of 6X months after the last spraying, 

 and the smaller percentage of winterkilled seedlings in the sprayed plots 

 (Table I) are worthy of note. 



At the time the first counts were made on the older seedlings (September 

 3) plots of the same size were also laid out in beds of both western yellow 

 pine and Douglas fir of the current year's sowing and were therefore 



