- Agronomic: corn
- Pest Management: botanical pesticides
I am investigating the efficacy of radish biomass management on slug and nematode populations and the impact on yield of no-till corn.
Use of improved, proprietary varieties of oilseed radish such a “Tillage” and “Groundhog” for cover crops has seen explosive growth in the past few years and industry representatives claim millions of acres are planted in the upper mid-west in any given year. Undoubtedly this growth in cover crop use has benefited the sustainability of agriculture by positively affecting soil quality, but experience indicates the potential for negative pest interactions, specifically the ability of radishes to create ideal habitat for slugs. These pests can devastate stands of subsequent crops, especially under no-till conditions, and we don’t have reliable control methods other than avoidance and helping the new crop out-grow its period of susceptibility early in the growing season.
Radishes may contain a built-in control method for slugs if managed for this purpose. All members of the mustard family produce glucosinolates which are converted to allyl-isothiocyanate upon plant decomposition. Mechanical disruption of cells (such as chopping the cover crop) may produce lethal concentrations of allyl-isothiocyanate to reduce pest populations. This is a common component of biofumigation, but is frequently followed by incorporation of plant residues and commonly, sealing the soil surface with plastic. Common wisdom and to a lesser extent, science suggests this step is necessary to maintain concentrations of the mustard gas because it’s highly volatile. Incorporation of residues requires tillage so is at cross purposes to no-till production.
It’s also possible that destruction of ideal slug habitat may reduce over-wintering populations and egg production. This may be the case where vegetation is chopped, allowing the biomass and soil surface to dry.
In field trials we are investigating the impact of radish management on pest populations, soil protection and corn performance and will communicate the results using a variety of outreach methods.
Project objectives from proposal:
Can manipulated (chopped) radish cover crop residues suppress slug and nematode populations and their damage to the subsequent corn crop?
Does manipulation (chopping) of the radish cover crop reduce its ability to protect the soil overwinter (does it reduce the conservation performance of the cover crop?)?