2022 CTRE: Deer repellent research and deer browse management in North Carolina
From Bert Cregg
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From Bert Cregg
Deer repellent research and deer browse management in North Carolina
Speaker: Jeffrey Owen - North Carolina State University (NCSU), Department of Forestry and Environmental Resources, Mountain Horticultural Crops Research & Extension Center, Mills River, NC 28759
Occurred 10:15 - 10:45 PDT, June 8, 2022
Abstract
Deer browse of young Christmas trees is a devastating problem for many Christmas tree growers in North Carolina and elsewhere. Injury results in culling and replanting of young trees, permanent degradation of tree quality, harvest delays, and eventual abandonment of farms with severe deer browse pressure. Growers have employed hunting, fencing, and repellents to deter deer from browsing with mixed results. Research conducted in North Carolina from 2002 to 2012 resulted in widespread use of inexpensive bulk deer repellents made of inedible egg or spray-dried red blood cell powders. However, these bulk materials were difficult to mix and spray, sometimes limited in availability, and only effective if re-applied on time.
Conversations at the 2019 CTRE meeting in Quebec City, Canada led to new deer repellent research using Trico, a European product manufactured from sheep fat. Trico was tested alongside bulk egg and blood repellent treatments in 2020. In 2021, Trico, Bobbex, and Thiram repellents were tested. Results suggest that all repellents tested were effective when re- applied according to recommendations. Trico was noteworthy for still protecting trees at the end of a six month reapplication period rather than the more common two month duration. Adding a new deer repellent to growers’ wildlife management strategies is a measure of success, but may not be adequate in the long term. A discussion of rotation-long deer browse management is crucial to sustainable Christmas tree production. Grower decision-making must involve cost of application, treatment duration, and risk management considerations. Repellents represent a relatively inexpensive treatment, but may be inadequate over a ten-year crop rotation.