Explore How Planting Green Affects Crop Insects and Disease

Planting green can be a risky business.

The practice of planting cash crops into green, living cover crops is gaining popularity, as farmers try to capitalize on its ability to create more cover crop biomass and better suppress weeds. But the potential of leaving a “green bridge” for insects and diseases to infest the emerging crop stand remains a concern for some growers and researchers.

A seminar series from the ag tech research organization, Precision Sustainable Agriculture (PSA), is featuring some of the work ag scientists are doing to figure out just how planting green affects crop pests. 

Planting Green & Insects

This April 2022 PSA seminar tackles the insect side of the issue with Matt Boucher, the state soil scientist for Maine, who conducted this featured research during his previous tenure at Penn State’s Tooker Lab

Boucher presented one year of data on how planting green affects crop pests such as slugs and cutworms, as well as their beneficial insect predators.

Overall, cover crop fields did show higher slug activity in the spring compared to conventional plots, the PSU team found.  But planting green didn’t significantly increase slug activity in the springtime compared to cover crop fields burned down earlier in the spring (planting brown). Even more interesting, higher spring slug populations in planting brown and planting green fields did not correlate with more slug damage to the crop, Boucher discovered. In contrast, the planting green fields did have a significantly higher probability of black cutworm damage. 

As for insect predators, the data was very clearly positive: They really liked the planting green fields. 

Overall, beneficial insects were significantly more active and effective against crop pests like slugs in planting green fields, Boucher said. “They’re present and they’re feeding like crazy!” he said. “It’s indicating that we’re increasing the amount of time that predators become an effective biological control.” 

Boucher also examined other factors, such as fall slug populations and corn stand establishment in planting green fields. See his full seminar presentation here or on PSA’s YouTube Channel:

Planting Green & Disease

In this November 2022 PSA seminar, Iowa State University research scientist Rashelle Matthiesen discusses her research on how cereal rye termination timing affects corn yield, seedling disease and stalk rot.

She found a curious mix of results. In some planting green treatments, rye termination timing did appear to have a significant effect on seedling disease. But for another group of common corn diseases – stalk rots – the planting green treatments had significantly less disease.

As for yield, Matthiesen found that planting green resulted in equal or higher yield than the control in 54% of the tested locations, while the practice was associated with lower yields than the control in 46% of the sites.

To see Matthiesen’s full research presentation, watch her seminar below.

You can find PSA’s entire seminar series under the Resources page of the group’s website here.

For more information on how planting green can help with weed suppression, visit GROW’s Cover Crop page in the Weed Management Toolbox. 

Article by Emily Unglesbee, GROW. Videos courtesy PSA.