11 



2. Maintain a vegetation-free area within at least 3 feet of tree 

 trunks. The use of herbicides may be necessary to accomplish 

 thi s. 



3. Eliminate brush and thick vegetative cover around orchard peri- 

 meters. 



k. Completely remove all fruit drops from the orchard. 



Tree Guards 



Maintenance of proper tree guards is the most effective measure for 

 preventing tree girdling by meadow voles, unless snow depth exceeds guard 

 height. Voles tunnel through snow to any depth. Trunk guards do not pre- 

 vent underground damage by pine voles. 



Galvanized hardware cloth is one of the best materials for tree guards. 

 One-quarter-inch mesh in 24-inch width is preferred. The cloth is cut large 

 enough to completely encircle the tree and allow enough room for 10 or more 

 years of growth. The cloth is formed into a cylinder and the cut ends are 

 used to fasten it together so that no gaps are left for the mice to gain 

 entry. Two or 3 short pieces of wire may be necessary to secure the ends. 

 The guards are embedded at least 2 inches into the soil to prevent the 

 rodents from burrowing underneath. An annual check of guards is recom- 

 mended, preferably before the ground freezes. Hardware cloth is difficult 

 to work with, and installation is time-consuming. 



Several rigid, perforated polyethylene or plastic mesh products are 

 being promoted for use as tree guards. Each is used in a way similar to 

 that of galvanized hardware cloth to form a cylinder which is buried in the 

 ground and is of large enough diameter to give free circulation to air and 

 to allow for growth. They are easier to handle than wire guards, but some 

 may be broken down by ultraviolet light and may have a limited life. 



Wrap-around plastic guards are readily available, cheap and easy to 

 install but are not recommended unless they are removed each spring and put 

 on again in the fall. Various borers seem to prefer trees with wrap-around 

 plastic or paper guards, and with their use the bark remains tender and har- 

 dens off slowly. The plastic may become brittle when weathered, and these 

 guards are difficult to keep in place on trees with uneven trunks or swollen 

 graft unions. 



Paper wrap-around guards are not recommended. They must be tied off 

 with string which can girdle the tree unless it is removed in the spring. 

 Very high populations of bark borers have been found in trees protected with 

 this material. The treated paper also weathers quickly, and the protected 

 bark remains tender and hardens off slowly. 



Rodent ic ides 



Poison baits are of two types: zinc phosphide and anti-coagulant. 

 Just one or two fresh grains or pellets of zinc phosphide baits can quickly 

 kill the vole that eats them, but it may take several days of feeding on 



