Research HighlightsEvaluating Deer Damage on Pennsylvania Soybean Varieties
By Barb Baylor Anderson
Deer pressure has gotten so high for farmers in southeast Pennsylvania that they can no longer profitably grow soybeans in fields that border timber lines. While it would be beneficial to rotate to soybeans rather than raise continuous corn in those fields, deer destroy the soybeans.
To find management solutions, the Pennsylvania Soybean Board provided checkoff funding in 2018 to Sarah Dohle, plant science assistant professor at Delaware Valley University. Dohle’s research plan sought to evaluate ways to mitigate deer damage in Pennsylvania soybean fields, including evaluating varieties that might be less susceptible to deer damage.
“When we talk about the value of funding research projects, I believe the value is in our return on investment (ROI),” says John Harrell, Pennsylvania Soybean Board chairman from Lebanon, Pennsylvania. “I see ROI in the quality and quantity of soybeans we produce. Quality is what sets U.S. soy apart from the rest if the world. We also get sustainability ROI through better herbicide and insecticide use and soil fertility which helps producers be better soil stewards.”
Dohle and a team of students established a field method for evaluating 28 current soybean varieties for deer tolerance. Tolerance was to be measured by change in yield with and without deer pressure. Yield changes could be based on deer preference for varieties or on rapid regrowth after grazing. However, deer pressure at the field site was so high – estimated at eight deer per acre – that none of the varieties survived without a deer fence. All plants were eventually eaten.
“The border strip had the first soybean shoots eaten while beans hidden below the weeds went relatively untouched by the deer until the later herbicide application exposed them,” Dohle says. “Based on this observation, delaying weed burndown or planting into cover crops may potentially protect soybeans from some deer damage early in the season.”
Dohle observed that fewer weeds were in the area protected by the deer fence because the soybean canopy closed out weed competition. No canopy developed with deer pressure.
As a follow-up, Dohle had a student in 2020 grow wild soybeans with extra pubescence from the USDA gene bank, hypothesizing that the hairy leaves might deter deer from eating them. However, when campus closed in March 2020 due to COVID-19, the project was abandoned.
“I still would like to test commercial and wild varieties in the field in replicated and randomized trials and sequentially fence the soybeans to allow for recovery after damage,” she says. “We figure the deer pressure will be so high that all the beans would be consumed again, but we hope that some of the genetics might promote faster recovery post damage.”
Ultimately, Dohle says wild soybeans tolerant to deer pressure in Pennsylvania could be crossed to breeding lines to add wild tolerance to cultivated high yielding lines. In addition, she says having an efficient, reliable method to evaluate deer preference and tolerance would make it easier for researchers to develop improved deer-resistant varieties in the future.
To find research related to this Research Highlight, please visit the National Soybean Checkoff Research Database.