METHODS OF COMBATING* THE MISTLETOE. 25 



A further item of significance in this connection relates to the 

 extension of mistletoe-infected areas. There exist quite obviously 

 local centers of infection. These are most easily seen in cases where 

 a large area is occupied by an open stand of mainly one species, such 

 as the mesquite at San Antonio and the blackjack oak at Calvert. 

 In traversing such timber lands one notes here an area of some 

 square rods or acres in which almost every tree is infected, followed 

 by a long stretch of timber land practically free from mistletoe. 



METHODS OF COMBATING THE MISTLETOE. 



An understanding of the habits of mistletoe, especially with respect 

 to the mode of spreading the infection, will suggest that the surest 

 way to prevent further spread of infection to new hosts would be to 

 prevent any berries from ripening. This would imply, of course, 

 the virtual extinction of mistletoe from any given community, and 

 it may be questioned whether in spite of its harmfulness such an 

 extreme measure is desired. As stated in the beginning, mistletoe 

 has in many cases, if not generally, a traditional hold upon the regard 

 of people which goes far toward condoning its harmfulness. It is 

 reported that a certain prominent citizen in improving his residence 

 property caused the branches to be pruned from one of his trees and 

 mistletoe to be substituted therefor. (By what means and with 

 what success is not stated.) Possibly one of the chief causes of the 

 present conditions lies in the fact that in tolerating the growth because 

 of its biological interest and because of its traditional setting the 

 parasite has insidiously multiplied upon trees until it has become 

 positively a pest. Those who have tried ineffectually for a decade 

 or more to rid valuable shade trees of mistletoe will doubtless be 

 ready, to waive considerations of sentiment and tradition in favor of 

 a radical movement looking to the extermination of the parasite. 



The immediate problem is to deal with trees which are already in- 

 fected. Here, again, a knowledge of the habits of mistletoe will show 

 that where the infection is upon small branches careful pruning of 

 these a few inches below the point where the parasite is attached to 

 the branch will effectually get rid of it. The chief difficulty in this 

 case is simply that of getting up high enough in the tree to do the 

 pruning properly. This difficulty would be materially lessened 

 by employing the common device in which pruning shears are 

 attached to the end of a pole. The shears are operated by means 

 of a heavy cord attached to the free lever arm. Xo indiscriminate 

 lopping of branches or breaking them off with ragged fractures 

 should be tolerated. Where, however, the infection is in the larger 

 branches or on the trunk in which the cortical roots of mistletoe have 



166 



