24 MICHIGAN AGRICULTURAL COLLEGE 



material and eighteen trees were left untreated as checks. The mater- 

 ials were applied with a brush and the entire trunk was covered from 

 the roots up to a point above where any injury would occur. Each tree 

 was labeled to indicate the material used on it. The trees were set 

 in the ground in two groups between the rows in an orchard of dwarf 

 apples. This orchard was heavily mulched. They were set in rows, 

 with the trees about one foot apart in the row and were distributed so 

 that those treated with any particular material were not grouped to- 

 gether. After setting, the trees were well mulched with straw and 

 cornstalks. They were set on February 15. There was no frost in the 

 ground at lhat time. 



Itvsultis. , 



On May 7th the mulch was removed and the trees examined. The 

 trees -were classified according to the degree of injury or the lack of 

 injury. A tree was classified as "slightly injured" if only a small spot 

 on one side had been chewed by the mice. Any injury worse than this 

 was classed as "severe." The number of trees in each class is listed 



in the accompanying table. These figures show that the injury was 

 very severe on every lot of trees regardless of the material used. The 

 lot of trees painted with thick bordeaux was injured least but there 

 was so much injury even on these trees that its use is not recommended. 



\ 



Recommendations. 



None of the materials used in this experiment are recommended for 

 use on fruit trees to prevent injury by field mice. Better results might 

 be secured by frequent applications but the expense for labor and ma- 

 terials would probably be greater than for good wire protectors. The 

 application of any of these materials would also be difficult when there 

 is snow around the trees as it would be necessary to cover the trunk 

 of the tree to the ground. Field mice will work under the snow and 

 the injury is usually close to the ground. 



Wire Protectors 



A very satisfactory protector can be made from quarter-inch square 

 mesh galvanized wire netting. Bands not less than eighteen inches in 

 width should be placed around the tree trunk. They should lap enough 



