Maya. 1921 Effect of Fcyyous Sulphate on ChloYOsis of ConifeYS 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 1 per cent solution at the rate of only 0.1 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. 
SEPT. 19/7 OCT. 19/7 
f 3 /2 2& '2 2# 
DATES OP EXAM/M/Vr/ONi 
/fPff/L / 9 /ff 
22 
Fig. 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 6 }i 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 
