On what plants are most odor repellents, including thiram, primarily used?

• A. Dormant trees and shrubs
• B. Fruit-bearing trees
• C. Annual flower beds
• D. Lawns and turf

Answer: (A)

Odor repellents work by making the plant unattractive to animals that would otherwise chew or rub on it, and they are most effective on woody, perennial plants that have exposed bark or buds during winter. Thiram, in particular, is often applied to the bark, buds, and lower trunks of dormant trees and shrubs to deter rabbits, voles, and other herbivores when food is scarce and animals are more likely to browse bark. That’s why this option—dormant trees and shrubs—is the best fit.

Applying these repellents to lawns, turf, or annual flower beds is less practical and less effective, because those plants are typically grown as herbaceous or ground-cover types with rapid growth and different feeding pressures, and repellents on green tissue tend to wear off quickly or are not as protective. Fruit-bearing trees fall into the same general category as woody perennials, but the scenario emphasizes protection during dormancy, when bark damage from winter feeders is a primary concern.