Statewide Slug Monitoring Project – Update #2

Many counties across Ohio are noticing slug damage in their fields this year. Slugs prefer fields that are no-till, especially 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. Management is difficult due to the nocturnal nature of slugs. During the day they take shelter under leaf litter and other debris in the field (Figure 1). Adding to management difficulties, slugs have all life stages present at any time in the field (eggs, juveniles and adults) (Figure 2). To learn more about slugs a newly updated fact sheet is available and can be viewed here: https://aginsects.osu.edu/sites/aginsects/files/imce/Slugs%20on%20Field%20Crops%20_%20Ohioline.pdf

Despite the growing concern, little is known about slug populations across Ohio. To better understand Ohio slugs, we are participating in a multi-state project  funded by the United Soybean Board, to monitor slugs in soybean fields across the region. Each field will be monitored using shingle traps for 9 weeks (3 weeks before plant, and 6 weeks after plant). Shingle traps consist of a 1-sq.ft. white roofing shingle secured to the ground with tent stakes. These traps provide a refuge for slugs to hide under during daylight. Each week, traps are checked in the morning by lifting the shingle and counting the number of adult and juvenile slugs underneath each trap. The data collected from this study will allow us to have a better understanding of the slug variations in Ohio and across the region.

Figure 1. Slug found on underside of leaf litter. 

Figure 2. Slug eggs.

While reports of slugs in fields are high across the state, the average number of slugs found under the shingle traps across Ohio remains low. The highest average from any reporting field in Ohio has been 1.8 slugs/shingle in Seneca County. The figure below shows the average number of slugs found under the shingle trap in each county from May 20^th – 26^th (Figure 3). The majority of counties in Ohio are reporting low numbers of slugs found under the shingle traps. Seneca had the highest average number of slugs (1.8) followed by Wayne (1.7). It is important to note that low slug numbers under shingle traps does not necessarily mean there are low numbers of slugs in the field, monitoring the number of slugs underneath traps slug trap numbers using shingle traps and analyzing what those numbers mean for overall slug pressure in Ohio is  

Slugs in Ohio

May 20^th – May 26^th

Figure 3. Average slugs captured from May 20^th to May 26^th. 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.