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Journal of Agricultural Research 



Vol. XXI, No. 3 



about 3 months old. The results with the young western yellow pine 

 (fig. 2) are more striking than those with the older stock. Autumn 

 losses, presumably due to late damping-off, were not affected by the 

 treatments; but winterkilling was entirely prevented (Table I). The 

 heaviest treatment seemed to give better results than the lighter ones, 

 so far as correcting chlorosis was concerned, both at the fall and the 

 succeeding spring examinations, but resulted after the third treatment 

 in the blackening of some of the leaves. The chemical injury was even 

 more marked at the time of the spring examination, when practically 

 every seedling in all the western yellow pine plots treated with the 2 per 

 cent solution showed chemical injury, whereas the plots treated with 

 the weaker solution showed none. 



With young Douglas fir (fig. 3) the amount of chlorosis initially present 

 was less, and the untreated seedlings as well as the treated improved in 

 color during the course of the experiment. In so far as chlorosis is 

 corrected, the results are similar to those secured with western yellow 



OCT. 2,1917: 



FIG. 3. Graph showing the effect of a ferrous sulphate spray treatment on chlorosis in seedlings of Douglas 



fir 2 to 5 months old. 



pine. On Douglas fir, however, the heaviest treatment was no more 

 effective against chlorosis than the lightest; the intermediate gave the 

 best results. In view of this and the injury to western yellow pine from 

 the strongest solution, it appears that only the intermediate strength 

 (i per cent) should be used on conifers, at least if repeated spraying is 

 practiced. 



Though the total area counted in all the spraying experiments with 

 first-year seedlings was small 12 square feet in the treated plots and 

 6 square feet in the controls the data obtained from the counts show 

 on the whole such consistent and decided improvement in the sprayed 

 plots as to leave no reasonable doubt about the therapeutic value of the 

 treatment for western yellow pine. Observations on the entire area of 

 the western yellow pine experimental plots (200 square feet treated and 

 120 square feet in the controls) indicate that the sample areas on which 

 the counts were made were reasonably representative of the entire plots. 



