20 



tender and hardens 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 slowly. 



Rodenticides 



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

 one or two fresh grains or pellets of zinc phosphide-treated bait can quickly 

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

 anti-coagulant baits to kill voles. Owing to the caching habit of pine voles, 

 poison baits that are taken by the species may not be consumed until much 

 later, or not at all. Zinc phosphide breaks down slowly in moist air, and it 

 loses its toxicity rather quickly if the bait becomes wet. To preserve the 

 toxicity of unused zinc phosphide baits, place the opened package within a 

 plastic bag and seal the bag tightly. 



Rodenticide Techniques 



Broadcast . Broadcast applications of baits can be effective against 

 meadow voles. However, they are usually not effective against pine voles. 

 Bait should be directed into live ground cover where meadow voles forage, 

 rather than into herbicide-treated strips. Most product labels limit 

 treatments to the postharvest, dormant period. The presence of dropped apples 

 can make baiting ineffective; however, as apples are a preferred food for 

 voles. All sound drops should be removed before bait is broadcast. If the 

 weather is wet and dark during the first few days after broadcasting, the 

 baiting effort will have been wasted. Wet weather and dark days discourage 

 vole activity, and wet bait loses potency and palatability. Try to bait just 

 before a mild, fair-weather period of several days. 



Baiting in Artificial Trails . Mechanical trail-builder baiting machines 

 construct trails beneath the soil surface and supply baits at regular intervals 

 for meadow or pine voles that enter those trails. According to the U.S. Fish 

 and Wildlife Service, which can furnish plans to construct the device, this 

 technique can be effective against both pine and meadow voles. Sod cover and 

 reasonably moist soil are required at the time the machine is pulled through 

 the orchard. Generally, one trail is made along each side of the tree rows, 

 beyond the wheel tracks, beneath the drip line of the trees, and in sod. 

 Trails should be cut 2 to ^ inches deep, with bait placed at ^- to 5-foot 

 intervals. 



Hand-baiting . Hand-baiting implies selective placement of baits where 

 vole activity is most likely or where active trails or burrows are located. 

 Bait is placed in quantities of one teaspoon, at the rate of 2 to 3 lbs per 

 acre. To greatly speed bait placement, bait stations such as asphalt roofing 

 shingles or split tires should be distributed beneath the trees in sodded areas 



