1907.] PUBLIC DOCUMENT — No. 33. . 175 



composition and in the effects produced on trees. Any sub- 

 stance which is likely to cause even the slightest injury when 

 applied to trees should not be employed, and when such sub- 

 stances actually cause the death of trees, it becomes a gross 

 offence to apply them to public shade trees. 



At the request of William B. de las Casas, Esq., chairman 

 of tlio Metropolitan Park Commission, the writer made an 

 examination during the summer of 1905 of a large number 

 of trees located in Middlesex Fells and other districts around 

 Boston, with a view to determining the effects of the various 

 so-called banding substances on trees. 



In addition to our numerous examinations of the effects of 

 these various substances on trees, we have tested a great many 

 in a critical way on small plants. Our conclusions relating 

 to the effects of the substances are based upon a larger number 

 of observations, together with numerous tests on stems, leaves, 

 etc., of a variety of herbaceous plants. Any substance which 

 causes injury to herbaceous plants may also produce the 

 same effect on trees, although the time necessary to produce 

 injury to herbaceous plants is brief compared to that necessary 

 to give rise to corresponding results in a tree. 



A good banding substance should not cause the slightest 

 injury to trees, or even to tender tissues. It should not 

 harden at low temperature, neither should it melt at compara- 

 tively high temperature. It should be inconspicuous when 

 applied to the tree, and easily put on and removed, and should 

 remain sticky during the entire season. 



Tanglefoot. — This material is now extensively used, and 

 is a semi-transparent, sticky substance, not affected by low 

 temperature (32° E.) or by temperatures under 125° or 

 130° E. Its principal bases are probably castor oil, resin 

 and wax, which are substances harmless to vegetable tissue ; 

 and, whatever the other constituents of this banding substance 

 may be, they do not render it harmful to trees. Tanglefoot 

 applied to a large number of plants possessing a thin epi- 

 dermis has never caused any injury. In short, this is the only 

 substance which we have met which stands all the tests a 

 perfectly harmless banding material should when applied 

 directly to plant tissue. 



