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anti-coagulant baits to kill voles. Owing to the catching 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 pre- 

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

 plastic bag and seal tightly. 



Rodenticide Techniques 



Broadcast applications of baits can be effective against meadow voles. 

 However, they are usually not effective against pine vole. 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 farm 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 bait is broadcast, the baiting 

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

 activity, and wet bait loses potency and palatabi 1 i ty . Try to bait just 

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



Baiting in Artificial Trails . Mechanical trai 1 -bui Ider 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, who can furnish plans to 

 construct the device, this technique can be effective against both pine and 

 meadow voles. Sod cover and reasonably moist soil is required at the time 

 the machine is pulled through the orchard. Generally, one trail is made 

 along each side of tree rows, beyond the wheel tracks, beneath the drip 

 line of the trees, in sod. Trails should be cut 2-4 inches deep, with bait 

 placed at ^4-5 foot intervals. 



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

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

 Teaspoon quantities of bait are placed, at the rate of 2-3 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 well in advance of baiting time. Over a period of weeks or months, 

 voles develop trails under these bait stations; trails that can be quickly 

 baited after harvest. 



Orchard Floor Sprays . Liquid Rozol" (chlorphacinone) is an anti- 

 coagulant formulated for spray application. Effectiveness depends on 

 thoroughly wetting and penetrating the ground cover. Before application, 

 the ground cover should be dry and mowed short enough for maximum spray 

 penetration. Voles are killed after repeated exposure to residues on the 

 ground and cover crop. It will not be effective when there is no surface- 

 feeding activity. 



