White cockle is a persistent weed in hayfields and no-till corn and soybean fields and it seems to be an increasing problem based on recent questions. I’ll start with a few key points about white cockle and end with some management comments. 

 

1. White cockle’s name is officially white campion, but you will most likely still see it as white cockle on some herbicide labels if it is listed.

2. White cockle’s life cycle is a biennial or short-lived perennial. It grows from the same crown and does not spread by roots. It is very successful in establishing from seed that germinates in either spring or fall.

3. Identification: White cockle seedlings are yellowish-green and soon grow into a rosette with opposite leaves with soft hairs. As plants get older, they may have a grayish-green color because of the hairs. The opposite leaf arrangement is easier to see on the stems that produce the showy white flowers. Flowers have 5 notched petals. 

 

Odd fact: White cockle plants have either male or female flowers. The female flowers swell and develop into the familiar round seedpods.

 

Important fact: White cockle, like many other weeds in the pink family, is not very sensitive to 2,4-D. Therefore, 2,4-D used alone in burndown treatments or 2,4-D used for weed control in winter wheat is not effective unless mixed with another herbicide. 

 

Management: White cockle generally is not a problem in spring-tilled corn and soybean fields. In no-till fields, herbicides are generally most effective in the fall. In particular, glyphosate will be more effective in the fall and should be used at a minimum of 0.75 lb ae/a (i.e. the old 1 quart rate). In the spring, glyphosate will give good suppression at this rate, but control may not be complete. The addition of Valor to glyphosate in the spring may increase glyphosate’s control of existing plants. Valor’s residual activity will help to control emerging seedlings. We’ve been highly successful in controlling white cockle in the spring with Gramoxone plus Sencor on a warm, sunny day, but only had good suppression on a cooler, cloudy day. Sencor is good to add to Gramoxone because it synergizes the Gramoxone. Sencor’s residual activity also helps to control emerging seedlings.

 

If white cockle is not controlled before planting corn or soybeans, many of the plants will likely be starting to or flowering by the time postemergence applications are made. In Roundup Ready soybeans or corn, glyphosate can be used to suppress these plants. However, no herbicide will control white cockle adequately in conventional soybeans. In corn, dicamba-based products (i.e. Banvel, Clarity, Distinct, Status) should suppress larger plants and kill seedlings. A preemergence application of atrazine should also prevent white cockle from emerging in corn in the spring. 

 

Overall, it is probably best to scout fields that might have white cockle in the fall. These fields might be those that previously had cockle or are hay fields going to corn or soybeans. If white cockle is found, a fall treatment of glyphosate should remove many plants and limit the problem the following spring. Also, plan programs that control spring seedlings by using either a residual preemergence herbicide or an effective postemergence herbicide. Otherwise, these little seedlings will develop into the rosettes that are more difficult to control in the fall or the next year.