56 
CAROLINE RUMBOLD 
solutions of lithium salts injected in the spring months may have an effect 
on the chestnut blight fungus in that the growth of the cankers on the 
injected trees appeared to be checked somewhat and the trees showed a 
tendency to form a callus about the canker. 
Investigations in Forfst Pathology, 
Bureau of Plant Industry, 
U. S. Department of Agriculture, 
Washington, D. C. 
EXPLANATION OF PLATES III AND IV 
Plate III 
Fig. a. Tree no. 185E. An 8-year-old, grafted tree 4.85 m. high, 8 cm. in diameter. 
Injected April 15 to June 25, 1913, with 10 liters of lithium hydroxide 1/500 G.M. Leaf 
collected June 20, 1913. This tree produced many large nuts in the autumn. The shaded 
areas in the illustration indicate the brown portions of the leaf. 
Fig. B. Tree no. 21C. A 16-year-old grafted tree 5.5 m. high, i.i cm. in diameter. 
Injected June 20 to October 16, 1913, with 26 liters of lithium carbonate 1/500 G.M. A 
diagrammatic drawing showing a cross section of portion of the trunk, a. Holes running 
up and down the trunk caused by the death of the cambium layer in the path of the injected 
alkali, b. The irregular year ring of wood formed during the injection period. 
Fig. C. Tree no. 114E. A 9-year-old grafted tree, 46 m. high, 9 cm. in diameter. 
Injected May 9 to 15, 1913, with 143^ liters of meta-cresol i/iooo G.M. The branch was 
cut August 15. Callus had formed along the edges of the paths of the solution, a. Diagram- 
matic drawing of cross-section of small branch, b. This year's ring of wood, normal in 
structure, c. The edge of the creosote stain. All tissue reached by the creosote was killed. 
Fig. D. Tree no. 114E. Small branch showing an edge of a path of injected creosote 
solution. Normal callus separated the living bark tissue from the injected dead tissue. 
Plate IV 
Fig. a. Tree no. 185E. An 8-year-old grafted tree, 4.85 m. high, 8 cm. in diameter. 
Injected April 15 to June 25, 1913, with 10 liters of LiOH 1/500 G.M. Injected again 
June II to June 17, 1914, with LiOH 1/200 G.M., and from June 26 to July 27 with 2 liters 
of LiOH i/ioo G.M. solution. Tree inoculated with Endothia parasitica October, 1913. 
Canker photographed October, 191 5, when it was noticed that the canker had stopped 
growing. - 
Fig. B. Tree no. 185E. Same canker as above, photographed in November, 1915, 
when the dead bark formerly covering the canker had been pulled off. The clean, healthy 
callus which had "cut out" the fungus was thus disclosed. On the side branch can be 
seen the check made at the time the tree was inoculated. At the base of the photograph 
can be seen the upper part of a canker caused by a natural infection at the fork of a branch. 
This canker also had been "cut out" by a callus. 
Fig. C. a method of injecting trees of any diameter. Link chains tightened by 
turnbuckles hold the rubber corks to the trees. Glass T-tubes thrust through the corks 
introduce the liquid into the injection holes. A tempered steel tube shaped like a cork- 
borer makes the hole for the injected solution. It can be driven into the tree through the 
horizontal arm of the T-tube after the apparatus is in place. A piece of rubber tubing is 
put on the free end of the horizontal arm of the tube, and the solution is cut off with a 
pinchcock after the drill is removed. 
