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Agronomic Crops Network

Ohio State University Extension


Statewide Slug Monitoring Project – Update #3

As we move into June, we continue to receive reports of slug damage on soybeans across Ohio. Slugs are more likely to be found in no-till fields where cover crops are grown. Slugs feed directly on the soybean, causing both seed and foliar damage that can result in complete loss of the plant. Because slugs are nocturnal, when you scout your fields, slugs may not be present; however, you may see signs of slug feeding such as holes in the cotyledon (Figure 1) or slime trails (Figure 2). You are more likely to find slugs actively present in your field if you scout early in the morning or on cloudy/rainy days.

Soybean fields that were planted within the last 2 weeks into no-till fields should be scouted for slug damage. Slugs can cause significant damage to young soybean plants at the VE stage compared to older plants that can outgrow the damage. If you notice poor emergence and holes in the cotyledons, slugs may be feeding on your plants. Additional scouting is necessary to confirm slug activity before management tactics, such as baits or replanting, are implemented. To learn more about slugs a newly updated fact sheet is available and can be viewed here:

One of our research objectives this year is to better understand slug populations in Ohio. To do this, we are participating in a multi-state project funded by the United Soybean Board, to monitor slugs in soybean fields across the region. Fields are monitored using shingle traps for 9 weeks (3 weeks before plant, and 6 weeks after plant). The data collected from this study will allow us to have a better understanding of the slug variations in Ohio and across the region. Weekly results are being posted in the newsletter, but it is important to note that a low county average does not mean slugs are not present in your county. If you planted soybeans into no-till fields, your fields should be scouted for slugs.

Figure 1. Slug feeding on soybean cotyledon. Yellow arrow pointing to slug on the plant. Photo credit: Amy Raudenbush

 Figure 2. Example of soybean damage on cotyledon and slime noticeable. Photo credit: Maddie Brillhart                                                                                                            

Currently, we are monitoring slugs in 12 counties across Ohio. The figure below shows the average number of slugs found under the shingle trap in each county from May 27th – June 2nd (Figure 3). Over the past week, the average number of slugs in some counties increased. Wayne County had the highest average of 6.2 slugs/shingle over the past week, up from 1.7 the previous week. The majority of counties in Ohio continue to report low numbers of slugs under the shingle traps; however, if you recently planted soybean into a no-till field, make sure you scout your fields, even if your county has a low average.

Slug Monitoring in Ohio

May 27th – June 2nd

Figure 3. Average slugs captured from May 27th to June 2nd. The bold number on the left indicates the average slug count for the week, followed by the standard number on the right which indicates the total traps set up in that county.


Crop Observation and Recommendation Network

C.O.R.N. Newsletter is a summary of crop observations, related information, and appropriate recommendations for Ohio crop producers and industry. C.O.R.N. Newsletter is produced by the Ohio State University Extension Agronomy Team, state specialists at The Ohio State University and the Ohio Agricultural Research and Development Center (OARDC). C.O.R.N. Newsletter questions are directed to Extension and OARDC state specialists and associates at Ohio State.