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 







70 90 



27O 



//O /3O /SO /7O J9O &O 23O 25Q 

 &/A/CE F/RST <Sf>ffrtY/NG ON fiVG. 2J917. 



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



yellow pine 14 to 18 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 



