Cover Crop Burndown 2014

Matthew Wiggins

Jackson, Tenn.
   Springtime is finally here and it is time to consider terminating winter-annual cover crops.  Many people have been questioning the timing of cover crop termination.  Much of West Tennessee has encountered a cool and wet spring, which has limited the biomass accumulated by the cover crops when compared to the last several warmer winter/springs. So do we delay cover crop termination to get more growth or wait?
   So far, spring of 2014 has been very different than 2013. In 2013, single-pass applications of gramoxone and glyphosate provided inconsistent control (15 percent - 75 percent) when cover crops were actively growing. Cover crops were rapidly growing and accumulating above ground biomass last April. These large amounts of vegetative biomass proved quite difficult to control with a single-pass of paraquat or glyphosate without tankmixing residual products (metribuzin, atrazine, fluometuron, etc.). Take this in to consideration as we move closer to planting season and this year’s cover crops start growing more aggressively. It might make sense to go ahead and tankmix a residual product with either paraquat or glyphosate to control more mature cover crops.
   Currently, cover crops are just now starting to grow as we get some sunshine and warmer weather.  This limited cover crop growth has allowed us to very effectively control (>85 percent) cover crops with a single-pass of gramoxone or glyphosate. I would expect this to change as we continue to get warmer weather. There are many benefits to allowing cover crops to grow, such as erosion prevention, early-season weed control, and even removing moisture from the soil profile to allow an earlier planting date.  However, cover crops can accumulate too much growth. Excessive growth can hinder planter effectiveness in maintaining seed-soil contact and can remove too much moisture from the soil profile and reduce germination. Therefore, most cover cropping scenarios need to be managed on a case-by-case basis, dependent on cover crop specie and growing environment. ∆
   Matthew Wiggins: Graduate Research Assistant, University of Tennessee