Cover Crop Termination Plans

By Rosie Roberts, CFE Conservation Agronomist

As we start the gradual warm-up of spring, it’s time for anyone with winter hardy cover crops to start thinking about terminating their cover. Cereal rye is a common choice, either by itself or as a base for a multi-species mix. Cereal rye is a winter annual that is seeded and established in the fall, turns dormant to overwinter, and starts to actively grow once snow cover melts and the weather slowly warms. As we drive around the countryside, most fields with cereal rye have already started to actively grow and are a bright green in contrast to other fields. This plant cover provides a plethora of benefits, some of which include protecting the soil surface form wind and water erosion, inhibiting early season weeds from germination, and improving soil health through water and nutrient holding capacities.

Timing your cover crop termination can be critical, especially preceding a corn crop. The recommendation in corn is to terminate cereal rye 10-14 days prior to planting, which helps safeguard corn germination rates. During colder springs, there is an added challenge of temperature to think about. Burndown chemicals are most successful on warmer days, when the plants are actively respiring and photosynthesizing. Most burndown herbicide programs are built around Roundup and a growth regulator like Xtendimax (dicamba) or Enlist (2,4-D). These systemic herbicides must be taken into the plant’s growing points for an effective kill, and cold temperatures slow plant growth and uptake. This is why it’s critical to terminate during a warm spell. The earliest optimal temperature range is nighttime temperatures above 40°F and daytime temperatures above 50°F for a few days. There is a second option for termination, called planting green, that allows for added biomass accumulation, better weed suppression, and increased soil health. Planting green is more common among no-till soybean operations, where the cover crop is terminated with less time between the burndown application and planting the main cash crop. This extended window of time provides an increased chance for warmer weather and effective herbicide kill. When planting green, you should ensure the planter has adequate downforce pressure as well as frequently check planting depth, as sometimes row units can plant shallow due to accumulated surface biomass.

In order to have a successful transition from cover crops to your main cash crop, it’s important to create a termination plan that takes the weather into account. While Roundup prices are up from years past, this is not an area to cut back on herbicide rates. To have a successful corn or soybean season, it first starts with adequate spring planning and cover crop termination.

Consult your CFE agronomist for the best chemical program for your operation.