Updated January 4, 2021:
Evaluation of detergents as a means of suppression of deer feeding injury to soybeans
4th Quarter Progress Report
During the 4th quarter field trials were harvested and yield data analysis was completed. A total of 15 fields were included in the study. Fields were located in Richland and Barnwell counties on university and private farms. 3 cooperating farms were involved in the project. Results of yield data and node count data indicated there were no significant differences in yield or number of nodes in relation to repellents used.
Greenhouse studies associated with this project were completed and data was analyzed during the 4th quarter. Greenhouse studies were used to evaluate the compatibility of deer repellent detergent products with herbicides common to soybean productions. Results indicate the repellents/detergents alone had no influence on plant growth. Some level of damage was recorded for each repellent plus herbicide combination tested. Downy plus Basagran produced the least injured treatment. Combinations of Basagran, Dual and Cobra produced significant injury to soybeans when combined with Tide or Irish Springs. This study showed a definite plant response to combinations of deer repellents and herbicide products used in soybean. Growers should use caution when tank mixing deer repellents with commonly used soybean herbicides.
Soybean Board Funded Research Update
January 4, 2021
Evaluation of detergents as a means of suppression of deer feeding injury to soybeans
Investigators:
W. Cory Heaton, Ph.D. Mike Marshall, Ph.D.
Wildlife Specialist Agronomic Weed Specialist
Sandhill REC Edisto REC
900 Clemson Road 64 Research Road
Columbia, SC 29224 Blackville, SC 29817
803-788-5700 803-284-3343
heaton2@clemson.edu marsha3@clemson.edu
Kendall Kirk, Ph.D.
Precision Agriculture Engineer
Edisto REC
64 Research Road
Blackville, SC 29817
803-284-3343
kirk2@clemson.edu
PROJECT OBJECTIVES AND GOALS:
The primary objective of this study was to improve our understanding of deer repellents and their utilization in soybean production. In order to reach our overall objective, we have identified the following as supportive objectives:
1. Determine optimum rates of detergents that may be applied to soybeans without injuring plants.
2. Determine tank mix compatibility of detergents with selected pesticides used in soybean production.
3. Determine effectiveness of detergents and rates for suppression of feeding injury.
4. Determine impact of detergent applications on soybean yields.
HOW PROJECT OBJECTIVES WERE MEASURED:
Preliminary Study
We evaluated the effectiveness of five common household detergents, soaps and/or fabric softeners for their ability to deter deer feeding injury. Trials began in March 2020 and continued thru May 2020. The five products tested were as follows: Downy Fabric Softener, Irish Springs bar soap, Gain, Snuggle, and Tide. For the preliminary tests, corn piles were placed in fields on Edisto REC. Game cameras were installed at each bait site to monitor deer activities. Once deer were observed feeding on every corn pile (about one week), a thirty-inch buffer was sprayed around the corn piles with a 5% solution of the respective detergent, soap or fabric softener. One bar of Irish Spring bar soap was boiled down into a concentrate and mixed with 10 gallons of water. The preliminary tests were replicated several times in each of the fields with varying distances between the plies to insure the products were not having an effect on adjacent piles.
Field Trials
Field tests were comprised of ninety-foot plots that were six rows wide with all rows being planted on thirty-eight inches. There were a total of seventy five plots arranged in a randomized block design and located within Barnwell County on four different farms, providing a total of 25 replications. Treatments at Barnwell County study sites included Irish Springs, Downy and untreated control. Additionally, field tests were conducted at Sandhill REC located in Richland County. Field tests at Sandhill evaluated Downy, Irish Springs, Gain, Snuggle, Tide and untreated control. Treatments at Sandhill REC were replicated 8 times. Plots at all study sites were located along the edge of fields in the border rows with the plots starting on the fourth row from the edge of the field. A four-wheeler equipped with a GPS and mapping software, outfitted with a ten-gallon tank and a three-row boom was used to spray plots. Plots were sprayed every two weeks beginning one or two weeks after planting for a total of three treatments. Damage ratings and plant heights were collected the same time plots were sprayed and two weeks after the last spray treatment. The center thirty feet of each plot was rated for deer feeding damage on a 0-5 scale (0 = no damage, 5 = 100% damage), and plant heights were collected randomly from ten plants in the center thirty feet of each plot.
Greenhouse Study
Greenhouse studies were conducted to evaluate the compatibility of deer repellent detergent products with commonly used soybean herbicides. Soybean seedlings were grown in the greenhouse in a commercial potting mix. At the 2-3 leaf growth stage, seedlings were sprayed with the following deer repellent products: Downy, Tide, and Irish Spring alone and in combination with Basagran (1 pt/A), Dual Magnum (1 pt/A), Xtendimax (22 oz/A), Reflex (1 pt/A), Roundup PowerMAX (32 oz/A), and Cobra (12.5 fl oz/A). The deer repellent products were mixed at a concentration of 5% of the final volume. The recommended adjuvants were included with the herbicides. The study was repeated twice with 4 replications per trial run. At 21 days after treatment, plants were clipped at the soil surface, placed in paper bags, and dried for 36 hours in 105F drying ovens. Afterward, biomass weights were collected. Data were analyzed using ANOVA and means were separated at the 5% level.
Findings
Preliminary Study
Analysis of trail camera photos indicated that deer were most reluctant to feed in corn piles that were treated with Downy fabric softener or Irish Springs bar soap. These conclusions were reached by considering the amount of time after applications before deer resumed feeding in the baited area. Findings from the preliminary study were used to select products for field trials.
Field Trials
Study plots in Barnwell County were harvested and yield data collected. Analysis of Barnwell County yield data indicated there were no statistical differences among treatments. The average yield from untreated control plots appeared higher than treated plots at every farm except the Long Branch Location (Figure 1), but the difference was not significant. The Long Branch Farm was comprised of smaller fields and located in a closer proximity to an occupied residence than the other fields. Downy and Irish Spring plots averaged about seventeen bushels per acre from the Long Branch location and the untreated plots averaged twelve and a half bushels, the difference between treated and untreated plots was not statistically different.
Study plots at Sandhill REC were not harvested and damage data was not analyzed. Differences in field topography and intensity of rain events compromised the integrity of the stand. Additionally, following the treatment period deer feeding intensity ramped up throughout the study field. Damage persisted thru the remainder of the growing season thru pod maturity. Deer were observed browsing on soybean pods extensively between leaf drop and dry down period prior to harvest. Once plants were suitable for harvest, moist soil conditions delayed harvest. Deer had completely removed the crop thru feeding activity prior to harvest.
Greenhouse Study
Soybean treated with the deer repellents alone did not show any injury (Figure 3). Overall, there was a trend when adding herbicides to the deer repellents where soybean injury increased. Downy plus Basagran was the least injured treatment compared to the untreated control. It was surprising to see growth reductions in the Xtendimax and Roundup treatments across all repellents. Similar to the Downy + Basagran, Xtendimax + Downy and Roundup + Downy had the least growth reductions compared to Tide and Irish Spring combinations. The oil containing herbicide formulations (Basagran, Dual, and Cobra) showed more injury across the repellents. This response was expected since they tend to produce significant foliar burn alone.
This study showed a definite plant response to combinations of deer repellents and herbicide products used in soybean. Growers should use caution when tank mixing deer repellents with commonly used soybean herbicides. The components of the detergent formulations can act to enhance the burn of the herbicides. More research is needed on investigating the cause of these effects on soybeans.
Figures
Figure 1. This chart displays the average yield for each treatment on each of the four farms in Barnwell County, and a combined average yield for all plots.
Figure 2. This chart displays the average node count among the treatments for each farm in the Barnwell County study area and the average node count for each treatment.
Figure 3. Soybean biomass as affected by deer repellents alone and in combination with herbicides. Abbreviations: UT, untreated; D, Downy; T, Tide; IS, Irish Spring.
Figure 4. Visual response of seedling soybean to selected deer repellents and herbicides. Photos were taken about 21 days after application.