Deer are the leading cause of crop damage by wildlife in Delaware. In neighboring Maryland, the government estimates showing approximately $10 million in losses annually, with 77% of those losses attributable to deer (USDA NASS 2011). Delaware faces greater challenges than many other soybean growing areas in the country due to smaller field sizes that are more often interspersed with and bordered by forested areas that provide refuge for deer, which emerge to graze highly palatable and nutritious soybeans. Farmers have regularly identified deer and wildlife damage as one of their top concerns, and frustrations by farmers are well documented in news media articles. Soybean yields in 2020 in certain fields at the Wye Research & Education Center in Queenstown, MD, were reduced by 20-30 bushels per acre in a field bordering a forested area. At a farm outside of Harrington, DE, yields were reduced by 66%. While hunting and crop damage permits allow some farmers to reduce deer population densities, some locations are not amenable to this due to factors such as landowners or neighbors that do not allow hunting, restrictions on method and time of take with damage permits, nocturnal grazing activity, and time required to harvest sufficient numbers of deer.

We seek to test the effectiveness of three deer repellent options on a 35-acre farm outside of Harrington, DE.

The project will be implemented as an exploratory case study at the Streett Farm outside of Harrington, DE. We will spray approximately ¼ of the field with each of three sprays and leave ¼ of the field as a control. We have researched as affordable options with pricing under $15/acre of raw materials for 4 spray applications over the growing season approximately every 2 weeks, Hinder, DES-X, and Plantskydd.

We will break the field into 3 sections to test each of the repellents (example fig. 1), and will leave an area of the field unsprayed as a control. We will place one to two 10’ diameter hogwire deer enclosure on each plot and control to assess yield potential and plant production in the absence of grazing.

Updated December 19, 2023:
Fields were sprayed 3 times with 3 different chemicals. Soybeans looked remarkable. Grazing exclosure data were cut and measured.

Updated December 19, 2023:
Initial results have been incorporated into Agronomy Day presentations given to over 230 people in Maryland. we are attempting to access precision agriculture data to better assess repellent efficacy and differneces between treatments. At first glance, they all seem to have worked quite effectively.

Updated June 5, 2024:
On the 35 acre field of cooperating farmer Joe Streett, we tested 3 different repellents and achieved yields of 45 bu/acre (+/- 2.9 bu/acre) for DES-X, , 42 bu/acre for Hinder (+/- 33.9 bu/acre), and 44 bu/acre for Plantskydd (+/- 5.8 bu/acre). For context, the previous year, the farm harvested a yield of 17.2 bu/acre in 2022. Analysis of precision agriculture data did not reveal significant differences between different types of repellents tested. The control area was a relatively small portion of the property and had similar yields, suggesting the repellents kept deer out of the field entirely. A small 4 acre field in the back of the property was also tested, and the soybeans survived, but the stand was so weak the farmer did not harvest the soybeans.

Our study suggests that in some cases repellents are an effective deterrent, increasing yields by approximately 25-28 bu/acre in the main farm field we tested. They do have some limitations, especially in very small fields (<5 acres) surrounded by lots of woodland/cover. Repellents also require labor and the ability to spray multiple times in the growing season, especially after significant rainfall. If rainfall lasts for long periods, this can hamper the ability to spray fields at ideal times.

Results of this repellent work presented to over 750 farmers at 8 agronomy meetings in 2023/2024. Please see attached presentation.

We conducted evaluation surveys after presentations that included multiple deer damage mitigation strategies, but including work from this repellent project. 184 survey participants projected a savings of $177 per acre, on an average of 233 acres. This translates to an anticipated average monetary saving of $40,938 per respondent. Cumulatively, the calculated savings to over $1,237,000 among all survey respondents, (even after the removal of four outlier respondents that suggested substantially higher savings). This figure is derived only from 184 survey respondents that completed the survey. Non-responding farmers may have had additional savings from crop damage.

We were able to accomplish project objectives efficiently and have remaining resources to test additional repellents in 2024. We plan to test DES-X (the least expensive option we tested in 2023) against Penergetic, an option that we have not tested, but claims to have reduced application needs.

View uploaded report