According to Fine Gardening.com, trilliums are resistant to insect pests that feed on its foliage. However, trilliums are favored by browsing deer, which can be devastating to the health and appearance of the plant. Deer feed on more than 500 different species of plants and consume more than 7 pounds of food each day. While deer prefer to feed in their natural habitat, they will wander into home gardens and yards when food is scarce and the competition for food is high.
Trilliums that are being damaged by deer browsing often have a shredded appearance because deer have no upper incisors and cannot produce a clean cut on foliage. Succulent, new growth is most susceptible to damage from feeding deer, with twigs and stems having a shredded appearance as well.
Placing area repellents near your trilliums may help reduce damage from browsing deer. These products produce a foul odor which discourages deer from coming near them to feed. Contact repellents are placed directly on your plants, causing them to have a unpalatable taste. Damage may also be prevented by placing susceptible plants such as trilliums close to your home, as deer will not typically come close to humans. While no plant species is deer proof, some are less preferred than others. If deer are a persistent problem in your yard or garden, you may wish to place less desirable plants there.
Fencing is the most effective way to reduce deer browsing in your yard or garden. Deer-proof fences should be at least 8 feet in height and constructed from sturdy, woven wire. Electricity may also be placed on your fence to discourage persistent deer. Homeowners with serious deer problems may apply for a nuisance permit to reduce the population, if available in your area. These permits allow homeowners to kill a specified number of deer each year. Deer damage in home landscape settings are much more likely when deer populations are high and the competition for food in their natural habitat is fierce.