Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/17/2007
Publication Date: 1/10/2008
Citation: Mcgiffin, M., Spokas, K.A., Forcella, F., Archer, D.W., Poppe, S., Figueroa, R. 2008. Emergence prediction of common groundsel (Senecio vulgaris). Weed Science. 56:58-65.
Interpretive Summary: Common groundsel is a troublesome weed in many horticultural crops, especially strawberry, in northern growing regions. Only a few herbicides are labeled for groundsel control in strawberry. Because chemical residues in fruit are a concern, these herbicides can be applied only within restrictive time periods that may not be optimal for groundsel control. Understanding and predicting the patterns of groundsel seedling emergence may help growers schedule herbicide applications in a more timely manner. Consequently, we developed simple predictive seedling emergence models based on soil temperature or an index that combined the effects of soil temperature and soil water content. We also checked the accuracy of these models using field data from Minnesota and Ohio. The soil temperature model did not predict patterns of seedling emergence as well as the combined temperature-water model. An index of soil temperature-water, adjusted for shading effects caused by straw mulch in strawberry, improved seedling emergence predictions. While common groundsel generally emerges from sites at or near the soil surface, the temperature-water model predicted emergence better when using index data derived from a 2-inch soil depth rather than the soil surface. The model allows growers, extension educators, and agrichemical industry personnel to understand the seedling emergence behavior of an important horticultural weed and, thereby, schedule weed control operations in a more timely and effective manner.
Technical Abstract: Common groundsel is an important weed of strawberry and other horticultural crops. There are few herbicides registered for common groundsel control in such crops, and understanding and predicting the timing and extent of common groundsel emergence may facilitate its management. We developed simple emergence models based on soil thermal time and soil hydrothermal time and validated them using field-derived data from Minnesota and Ohio, USA. Soil thermal time did not predict the timing and extent of seedling emergence as well as hydrothermal time. Soil hydrothermal time, adjusted for shading effects caused by straw mulch in strawberry, greatly improved the accuracy of seedling emergence predictions. While common groundsel generally emerges from sites at or near the soil surface, the hydrothermal model better predicts emergence when using hydrothermal time at the 5 cm depth rather than 0.005 cm, probably due to the volatility of soil temperature and water potential near the soil surface.