Weed Management

One major benefit of planting cover crops is their contribution to weed management. They provide a physical barrier and act as a weed suppressant. On this page, find resources on weed management and control with cover crops, including advice on using herbicides, pesticides, and burndown. Find tips on rotating cover crops and pesticide drift.

Weed Management With Cover Crops

Weeds are plants whose undesirable qualities outweigh their good characteristics. They also tend to be naturally strong competitors. An understanding of the life cycle of weeds allows producers to make informed choices on which weed management techniques to use. This knowledge also helps agronomic crop producers decide whether they can control annual and perennial weeds after silage harvest or in fallow areas.

Cover crops are commonly used as a smother crop. When used in this way they shade and out-compete weeds. Cover crops are also an effective herbicide-resistance management tool. Before seeding cover crops, however, there are several things to consider such as herbicide carryover, fall burndown applications, and herbicide rotational restrictions when the cover crop becomes a forage crop.

The use of herbicides is another method of controlling weeds. When applying herbicides to crops all private applicators and commercial businesses have to keep a Pesticide Application Recordkeeping Manual. Penn State Extension is currently researching the effectiveness of The Harrington Seed Destructor when used during harvesting of small grain crops.

Another way of managing weeds is to use conservation tillage systems. These systems utilize cultural, mechanical, and chemical control tactics.

Cover Crop Termination and Burndown Herbicides

Cover crop termination is crucial in order to maximize the yield from the main crop. One of the most common ways to kill cover crops is with herbicides. The effectiveness of herbicide burndown depends on the species and growth rate of the cover crop, the environment, the herbicide, and the rate at which crop producers use it.

The weather can make spraying burndown herbicides a challenge. Air temperatures before, during, and after application are also considerations that you shouldn’t overlook.

Herbicide Spray Drift

When applying herbicides, ensuring it stays on the intended target is critical. Wind can be a big problem when spraying herbicides, particularly if the crops being sprayed are adjacent to sensitive crops such as vineyards or specialty crops.

Herbicide drift and drift-related damage could prove very costly. You might not know it’s happened until you get a call from the Department of Agriculture or even a lawyer. Luckily, crop producers can take steps to reduce spray drift, such as spraying at low wind velocities, for example. Reducing spraying pressures and increasing carrier volumes and application rates are also very effective.

Herbicide Considerations for Cover Crops

Consider a variety of factors when applying herbicides. Timing, for example, is of paramount importance. Certain herbicides are more effective when applied prior to planting. There are herbicides that are better applied in the spring. Spring oat herbicide options include Callisto, Harmony SG, and Stinger.

At the other end of the production cycle, herbicides such as Aim, Anthem Flex, and PowerFlex HL are more effective when applied in the fall to help manage winter annual weeds.

During the application of herbicides, one of the most important considerations has to be soil persistence, or soil residual life. This factor is especially important when planting a sensitive rotation crop. Herbicide persistence can also influence successful cover crop establishment.

The application of herbicides can take place both pre- and post-planting. There are, however, application restrictions if the crop is being harvested for silage, forage, grazing, or grain.