GIVING MEDICINE TO TREES 



361 



of the "T" tube. The free end of the horizontal arm of 

 the "T" tube was tipped by a piece of rubber tubing; 

 after the solution filled the tube, a tempered steel cutter 

 was inserted through this horizontal arm of the "T" tube 

 and driven through the bark of the tree. In this manner a 

 small hole was made in such a way that no air could clog 

 the vessels of the wood, and the solution to be injected 

 began immediately to enter the tree. After the steel drill 

 was removed, the free end of the rubber tubing was 

 closed by a pinch cock. By this method any desired num- 

 ber of injections were made at one time. In these experi- 

 ments, the hole cut for injection purposes was one-fourth 

 inch in diameter and penetrated the wood to a depth of 

 two annual rings. 



It was found that all kinds of chemicals in solution 

 could be introduced into the trunks, provided there was 

 sufficient transpiration (evaporation of moisture) from 



FURTHER ALONG IN THE OPERATION 



This is the same canker as shown in the preceding illustration, with the 

 dead bark removed, exposing the healed up edges of the blight canker. 

 A year later this tree had thrown off the chemical and had become rein- 

 fected. However, this experiment indicates interesting possibilities for 

 controlling tree diseases by injected chemicals. 



the leaves to keep the sap moving. The transpiration was 

 greatest in the case of chestnut trees when they were in 

 full leaf and the day was sunshiny, dry, and a breeze was 

 blowing. On cold, rainy days the trees took up very little 

 of the injected solutions. The season of the year caused 

 a great variation in the amount of solution absorbed by 

 a tree, and also as to the part of the tree where the 

 injected chemical went. For instance, if a lithium solu- 

 tion was injected in the autumn, when the nuts were 

 ripening, a large amount of lithium collected in the fruits 

 and in the ends of the fruiting branches. In the early 



TREATMENT FOR LARGER TREES 



A number of injections had to be made at one time in the larger trees, 

 enabling the chemical solutions to reach all parts of the tree. This illus- 

 tration shows three glass containers hung in a chestnut tree, and a chain 

 clamp that was used to hold the tubes in the holes made through the 

 bark. On a clear day in midsummer a tree of this size absorbed many 

 quarts of solution. 



spring, when the leaves were unfolding and growing, the 

 lithium spread through the tree and less of the chemical 

 reached the leaves. In Pennsylvania, June was the best 

 month for injection so far as the rate of intake was 

 concerned ; then July, May, August, September, October 

 and April. The rate of intake varied more in April, 

 May and June than in the summer and autumn months. 

 Solutions of organic compounds went into the trees more 

 readily than solutions of inorganic compounds, and the 

 "true solutions" more readily than the colloidal. The 

 average amount of solution absorbed through a single 

 injection hole by an orchard chestnut tree, 15 feet high 

 and with a wide, rounded top, ranged from one-fourth 

 pint per day in April to three-fifths pint per day in June. 

 But there are records of three and nearly four quarts of 

 solution passing through an injection hole one-fourth 

 inch in diameter in 20 hours. Chemical solutions, with 

 very few exceptions, were absorbed more readily than 

 the pure water. Also, the more concentrated the solutions 

 of chemicals, the more rapidly they were absorbed. In 

 several cases, lithium injected into the trunk could be 

 detected 10 hours later in the leaves of branches at the 

 top of the tree. 



Fifty-six organic and inorganic substances in solution 

 were injected. The trees used in the experiments were 

 orchard trees, for the most part Paragon scions grafted 

 on native chestnut stock, but some trees growing under 

 forest conditions were also injected. Most of the trees 



