Deer BrowseHVPHC offers a treatment to help keep the deer from devouring your plantings. HVPHC uses a product called Thyram which is applied to all deer susceptible plants in mid November. The product leaves a grayish film on the plants, which when deer nibble, it leaves a nasty taste in their mouth. Thyram generally will provide up to 6 months of protection to your plants. In ideal conditions this product works very well, except during very snowy winters, such as the past winter, when snow levels averaged 4 to 6 feet deep for the entire season. When the deer are starving, they will eat what ever they can, regardless of how it tastes, just as you would.