Mar. i8. i9is Effects of Misiletoe Oil Young Couifers 717 



the elaborated food materials for its early development the following 

 season. If this food material is reduced in amount b}' its becoming 

 localized in other parts of the tree, the growth of the main shoot must be 

 necessarily retarded (PI. 37, B), and the bud itself will form earher in 

 the season and be much reduced in size. Two yellow-pine trees, each 

 8 years of age, one with a conspicuous infection with broom formation, 

 the other entirely free from infection, were carefully observed to deter- 

 mine this point. The former not only started the elongation of the main 

 shoot nine days later than the other tree, but ceased to develop altogether 

 at the end of the first month. The shoot of the uninfected tree continued 

 to elongate for two months and showed a gain of 1 1 inches over that of the 

 infected tree. The trees grew under exactl}' similar conditions, and their 

 root systems were practically equal in extent. Kirkwood ^ states that — 



It is improbable that the whole growth of the new leader is at the expense of the food 

 stored in the bud alone. That from other parts also doubtless contributes, but the 

 tendency is to crowd the formative materials toward the extrmities of the main shoot 

 and the branch. In the sharing of these materials the main shoot leads and the 

 branches follow in order of their importance. The principal growth, however, is 

 undoubtedly at the expense of the locally stored materials, the substances stored else- 

 where having their part to play in the development of the tissues in their immediate 

 proximity. 



The storage of food in the shoot and branches is exactly what the 

 formation of brooms and burls prevents in a large measure in all parts of 

 the tree above the seat of infection, and eveaatually results in retardation 

 and the appearance of spike top or staghead. The writer has repeatedly 

 called attention to this in previous publications. In order to demonstrate 

 that there is an actual storage of food materials in mistletoe brooms greater 

 than that of normal branches the results of an experiment may be given. 

 Late in the m.onth of October, 191 4, after the leaves had fallen, 10 mistle- 

 toe brooms and 10 uninfected branches from points ranging from 5 to 15 

 feet above the fomier were cut from a western larch and thrown in a damp, 

 shady ravine. In June of the following year the brooms and branches 

 were examined with the following result: Practically all foliar spurs of 

 the brooms developed needles in proportion of about one-third of the 

 normal length. A fev/ of the foliar spurs of the uninfected branches pro- 

 duced needles barely protruding from the bud scales, and in most cases 

 there was no leaf production whatever. Observation of brooms in the 

 crowns of larch cut late in the fall during logging operations showed in 

 the production of needles in the spring that there must be a great localiza- 

 tion of elaborated food materials in the branches of the brooms over that 

 of the normal branches.'* The latter showed no signs of foliation. 



' Kirkwood, J. E- the influence op preceeding seasons on the growth of yellow pine. In 

 Torreya, v. 14, no. 7, p. 118. 1914. 



* Certain parasitic fungi also cause a flow of building materials to the place of infection. See GoebEL, 

 K . E. EINLEITUNG IN DIE EXPEKIMKNTELLE MOKPHOLO'^IE DER PFLANZEN. p. 75. Leipzig uud Berlin. 



1908. 



3832G°— 18 3 



