Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/27/2009
Publication Date: 10/9/2009
Citation: Mirsky, S.B., Curran, W.S., Mortensen, D.A., Ryan, M.R., Shumway, D.L. 2009. Control of cereal rye with a roller/crimper as influenced by cover crop phenology. Agronomy Journal. 101(6):1589-1596.
Interpretive Summary: There is a need to integrate the soil improving properties of no-tillage agriculture with those of organic farming. Weed suppressive cover crop mulches are an essential component of this integration, however, effective cover crop control and the timing in which management must occur are not well understood. Our research addresses this need by assessing the influence of planting and termination date on successful mechanical control of a cereal rye cover crop using a roller/crimper. Percent mechanical control of cereal rye was improved as rye matured. The two cereal rye cultivars were both consistently controlled at flowering. Cereal rye growth and development to flowering was best estimated when separating the effects of growing degree days accumulated in the fall from those accumulated in the spring. Cash crop fall harvest and spring planting times constrain opportunities for incorporating cover crops into crop rotations. As a result, a growing degree day-based phenological model coupled with an understanding of the optimal growth stage for mechanical termination enables more strategic decisions regarding cereal rye planting and termination date. This information will be used as a decision support tool by extension personal and farmers as well as facilitate wider adoption of cereal rye cover crops.
Technical Abstract: Adoption of reduced tillage practices have been driven by the need to enhance soil quality, minimize field labor time, and scale up farm size. However, concerns about increased reliance on herbicides and in organic production call for production practices that can reduce tillage while also reducing herbicide use. This research assesses the influence of planting and termination date on mechanical cover crop control efficacy using a roller/crimper to limit tillage and herbicide use. A thermal-based phenological model using growing degree days (GDD; base 4.4 ºC) was developed to predict cereal rye (Secale cereale L.) growth stage. Mechanical control of cereal rye increased as rye matured. Variations in cereal rye cultivar growth rates were observed; however they responded similarly to rolling when terminated at the same growth stage. Consistent control was achieved at a Zadoks growth stage 61 (rye anthesis). A thermal-based phenological model separating the effects of heat units accumulated in the fall (FallGDD) from those accumulated in the spring (SpringGDD) best predicted the phenological development of cereal rye. Predicting when cereal rye can be successfully controlled using a roller/crimper along with the use of the thermal-based phenological model should aid growers in decision-making regarding cereal rye planting and termination date.