To preserve toxicity of unused zinc phosphide baits, place the opened package within a plastic bag and seal tightly. Rodenticide baits may be attractive to domestic pets, birds and other non-target wildlife. As with all pesticides, use good judgement and take reasonable precautions to avoid problems. They are usually not effective against pine vole. Placing the baits within a weed-free herbicide strip will probably not be effective because voles avoid open ground.
Most product labels limit treatments to the post-harvest dormant period.
The presence of dropped apples can make baiting ineffective, however, as firm 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 palatability. The best timing for bait application is soon after a postharvest mowing, and before a 3 day period of sunny, dry weather.