PINE MICE - WHAT'S NEW? 



U.S 



Edward R. Ladd 

 Fish and Wildlife 



Servi ce 



For more than 30 years, the Pine Mouse has been the subject 

 of great interest to orchardists in the Eastern United States. 

 Their major concern has been the damage caused to root systems 

 by this animal in its search for food. The root damage is such 

 that, except in extreme cases, the tree is not killed in one sea- 

 son. Instead, its decline may take several years and be seen as 

 lost vigor and production--as well as reduction of revenue to the 

 grower. 



ce was held in the State of 

 and accomplishments of per- 

 result was a more clear under 



under way, 



as a more 

 search is 



till need coverage 



s s- 



Much of the program was devoted to delineating the overall 

 problem areas (see map) and the variation or intensity of the prob- 

 lem within that area. Perhaps the material is best summarized by 

 stating that the intensity of the pine mouse problem can and does 

 vary by orchard--and even by blocks within an orchard. Some areas 

 may have pine mouse problems to the extent that tree loss or dam- 

 age is heavy; yet, neighboring blocks of trees, or orchards, will 

 have a minimal problem--or none at all. 



Of major interest to all attending the program were the re- 

 search programs being conducted on the pine mouse. A short resume 

 fol 1 ows . 



1. CHLOROPHACINONE AND HERBAGE AS POTENTIALS FOR PINE MOUSE DAM- 

 AGE CONTROL .--Frank Horsfall , Jr., Virginia Polytechnic Insti- 

 tute and State University, Blacksburg, Virginia. 



Dr. Horsfall, for the past several years, has been working on 

 a concept of integrated control. His work has developed a list of 

 grass and forb (broadleaf plants) species that create a balanced 

 habitat in the orchard. Such a balance of species contains numer- 

 ous plants actively sought as food by pine mice; the theory is 

 that with a surplus of desirable foods available, pine mouse dam- 

 age to tree root systems would be minimal. 



Dr. Horsfall has extended his work on the balanced food con- 

 cept into the field testing of an experimental anticoagulant, 

 Chlorophacinone . Using the selected plant species as ground cover 

 under trees, the experimental Chlorophacinone has been applied as 

 a ground spray and the resulting controls measured. 



