i6o 
Journal of Agricultural Research 
Vol. XXI, No. 3 
oxygen hunger as a very probable and effective stimulus in inducing 
chlorosis in a mesophyte like Douglas fir in an excessively wet soil. 
SPRAYING WITH FERROUS SULPHATE 
Spraying with ferrous sulphate was tested on western yellow pine and 
Douglas fir. The first tests were on seedlings of the former species 
approximately 14 months old. Plots 4 by 10 feet were laid out, series I 
in beds in which chlorosis was not serious, and series II in beds in which 
it was very prevalent. The two plots in each were adjacent and parallel. 
Care was taken to choose plots as nearly as possible identical in vigor, 
number of seedlings per square foot, and amount of chlorosis. One of 
the plots in each series was sprayed with iron-sulphate solution at the 
rate of 2 gm. of sulphate per 100 cc. of water, and the other was given an 
yellow pine 14 to x8 months old. 
equal quantity of water only and was used as a control. The spraying 
was done with a hand-spray pump and was begun on August 2, 1917. 
In each case the plot selected for the treatment appeared slightly more 
chlorotic than the control at the time of the first treatment. On August 
24, after two sprayings, it was evident that chlorosis had been decreased 
but that chemical injury to the youngest growth had resulted from the 
treatment. This injury is somewhat surprising, in view of the successful 
use of 8 per cent solutions on pineapple ( 12 ). The difference in results 
may, of course, be due to difference in the localization of the solution on 
