Be Thankful For a More Normal Spring, But Be Wary of Slugs as Planting Progresses
Posted: May 7, 2013
Thus far in 2013, we are pretty close to average degree-day accumulations. The PA-PIPE system displays maps with degree-day accumulation and departure from average, which can help time planting and scouting (click here to access these maps, follow the link at the top of the page, choose “Public Map”, and then the mapping options are on the right side of the page). The “departure from average” map shows that the southern, southeastern, and some of the central regions are a bit 50-100 or so heat units behind average, whereas western, northern, and the remainder of the central region are near normal accumulations or even slightly ahead.
While the activity of some pest species is predictable with degree-day accumulations, one exception thus far has been slugs. Slug egg hatch seems to be driven by a combination of heat and moisture. Eggs have started hatching in Delaware, according to Joanne Whalen at the University of Delaware, and based on our past experiences we can probably expect egg hatch in Pennsylvania this week or the next.
In recent years, growers in Pennsylvania and the Mid-Atlantic region in general have suffered from slug damage. We at Penn State have an active research program on slugs and different factors that influence their populations, but we have also been collaborating with extension specialists and educators in the region to gather the best information we can on slug biology and management. Ron Hammond, for example, at Ohio State put out a nice update on slug management this week in their CORN newsletter.
One of our regional slug collaborations has resulted in a website that we see as a local clearinghouse for biological and management information on slugs and was funded in part by the Northeastern IPM Center and Penn State. This site has information from University-based resources around the region (Penn State, Delaware, Ohio State, Virginia Tech, Maryland), but also has a new mapping function. The goal of the mapping capability is to identify fields that are usually infested with slugs to determine if soil type, quality, slope, etc. influence slug populations. This portion of the site requires registration, so if you are interested in collaborating with us on this effort, please drop me a note. Otherwise, when you have slug questions, please use the site and send me any feedback you might have.