2020
Impact and Potential Control Measures for Vole Populations in No-Till Soybean Fields Year 2
Contributor/Checkoff:
Category:
Sustainable Production
Keywords:
Biotic stressCrop protectionField management Pest
Lead Principal Investigator:
Matthew Springer, University of Kentucky
Co-Principal Investigators:
Project Code:
Contributing Organization (Checkoff):
Institution Funded:
Brief Project Summary:

Cover crops have been implemented to help decrease loss of soil to erosion, improve soil quality, and act as a part of an integrated weed management strategy. Adoption rates have been high across the country but not without new problems arising for some producers. The act of planting crops and having vegetation present during winter months has created quality vole habitat within cover cropped fields. Unfortunately, little is understood about the extent of damage caused by voles or any techniques to limit or control vole populations within soybean fields. Rodent control in this situation is made difficult due to restrictions associated with rodenticide application within production fields....

Unique Keywords:
#insects and pests
Information And Results
Project Deliverables

Objective 1: Survey soybean producers and fields across the state to estimate the amount of vole damage on soybean production and if there are certain types of cover crops that inherently have lower vole populations than average.
Results from surveys should help us understand the overall impact voles are having on soybean production within the main regions of Kentucky. Information on vole-caused replanting, loss in production, and occurrence of vole issues by acreage will all help us determine the severity of the vole issue. Preliminarily determining the role of different cover crops and how they correlate to vole damage will help inform future research in regards to selecting the types of cover crops to plant. This information may be an initial way for producers to help reduce vole populations and issues as we do not have any information related to this option at this time.
Objective 2: Evaluate three different pre-planting “burn down” application periods and their effect on vole populations and subsequent damage rates to emerging soybeans.
Previous research has shown “burn down” timing to be important for vole control within soybean fields (Hines 1993). Testing different timings of burn down while monitoring vole populations and movement related to cover crop vegetation will help us determine the importance of this potential vole control method. The results from this object will guide future recommendations to producers along with any needs for further research to help solve the vole problem for producers.
Objective 3: Determine how the three pre-planting burn down treatments affect weed populations and communities that may influence soybean production.
Results from this objective will help determine if there a decrease in weed control benefits from cover crops due to the different burn down treatments. We need to ensure that any methods used to control vole damage are not countered by a potential proliferation of weeds and poor soybean establishment.

Deliverables to Soybean Board and Soybean Association Members: Estimate the rates at which voles are impacting the production and incomes of Kentucky soybean farmers. Participation in extension field days to help educate producers on best management practices for dealing with vole populations on their farms. Creation of extension publications outlining estimation and effective methods to use for vole population control.

Final Project Results

Updated November 11, 2020:

View uploaded report Word file

Holey Voley: Vole Issues in Kentucky Soybeans Matthew T. Springer, Assistant Extension Professor of Wildlife Management, Kentucky Wildlife Extension Specialist There are many things that are on the minds of soybean growers as they work diligently to produce a quality soybean yield each year. Historically, voles issues were not even an afterthought. Unfortunately, it seems that in Kentucky, much of the upper-South, and probably even more so in Midwestern soybean fields, voles are now something that are on producers minds as a potential problem. So what is driving the change? There is anecdotal evidence that this uptick in vole related issues is tied to no-till production practices. Potentially adding to that are the increasing presence of cover crops in fields. Voles are forage feeders that have a wide variety of diet. Unlike some small mammals, voles are active feeders year-round and have been known to store food in their burrows for winter. Due to the nature of the vole’s diet, they can be immensely destructive on agricultural plants (Figure 1) and can very much take advantage of cover crops as a food and cover source through winter. Mice are less likely to cause an issue with newly growing plants due to a different diet(Figure 2). The number of producers having issues with voles was noticeable to me as I started my Wildlife Extension position in 2016. Our county ANR agents began asking more questions on voles in crop fields and when I talked with soybean producers the topic would come up in conversation in increasing frequency. After researching potential control methods, it was quickly evident that there were many folks across the country dealing with the issue but very little research developing methods to combat the problem at the scale our row crop producers’ work. Many suggested solutions included, snap trapping populations, mowing field borders, or encouraging natural predators. One of the few research projects on voles in no-till systems occurred in Southern Illinois in the early 90s by Ron Hines at the University of Illinois. He had tried a few different methods to control voles in no-till fields including alternatively feeding them cracked corn when beans sprouted, tilling, and application of pre-emergent herbicide 1 month prior to planting. His preliminary data suggested that the later technique may hold the most merit to limit vole damage over time, especially since the application of tilling causes the loss of all the soil health and erosion advantages of a no-till system, and alternative feeding is another input cost as well as holding the potential to increase vole populations over time. In 2018, Kentucky Soybean Board (KSB) believed that dealing with voles was an important issue for producers and funded a proposal to test the impacts of different pre-planting herbicide application times to cover crops on vole populations from 2018-2020. In the winter of 2019, a University of Kentucky graduate student funded by the KSB, began research in Hardin County Kentucky to test Hine’s recommended herbicide treatment regime. The student began by reaching out to ANR county agents, soybean producers, and crop scouts to locate fields that had historically dealt with large vole populations and vole caused damages in their fields. Several producers were kind enough to let us check out fields they knew they had issues with voles in the past and the student began walking those fields to identify the locations of all vole colonies. What became obvious very quickly was the variable nature of the vole colony locations. It was believed that these colonies would be closely tied to field edges, near existing grasslands, a potential source population that had individuals immigrate into the field. What you can see is that vole colonies, marked in yellow, were spread out all over the fields not just along the outside edges (Figure 3). For the experiment, we identified and used 8 fields over two seasons, with each field having all three treatment plots, each 1 acre in size located in the areas with the highest numbers of vole colonies within the fields. These treatments included spraying cover crops 4 weeks, 2 weeks, and immediately before planting, The hypothesis was that the loss of vegetative cover and food prior to planting would make the voles leave the field or more likely to be predated. We monitored small mammals’ populations within these plots using Sherman traps during the entire study period. We were able to catch thousands of rodents and hundreds of voles during our trapping seasons. The results from the herbicide treatment were not a clear as Hines had found. Weather limited our ability to apply treatments at the planned times, but we were able to collect data in all of our plots. Unfortunately, little support exists within our data that terminating cover crops early impacts vole population numbers. This may be due to the variable pace at which cover crops died across the treatment plots. But the more important aspect to this is that these are real world scenarios for producers so the advice of burning down cover crops as early as possible may need to be paired with other practices like raptor perches, or maybe spot tilling in areas with extreme vole densities to impact vole numbers. With this being the first attempt at this problem we look to continue test alternative methods to help producers deal with this issue while maintaining all the benefits of cover crops. We believe that using the findings from KSB funded project, we will be able to obtain alternative funding from federal agencies to continue to identify a solution for our soybean producers.

The United Soybean Research Retention policy will display final reports with the project once completed but working files will be purged after three years. And financial information after seven years. All pertinent information is in the final report or if you want more information, please contact the project lead at your state soybean organization or principal investigator listed on the project.