South Dakota: Pre-Harvest Weed Control Options

Row crops are maturing fast and some are showing a lot of weed escapes from waterhemp, velvetleaf, and marestail. To reduce germination of weed seeds and help with harvest late spraying or pre-harvest spraying may be an option for these fields.

Herbicide Options

The growth regulator herbicide 2,4-D, can be sprayed on corn after the brown silk stage according to most labels. To control broadleaf weeds use the maximum recommended rate. Other herbicides used for pre-harvest weed control have to be applied after the crops are mature and in the dry-down stage. Growth regulator-type herbicides like 2,4-D or dicamba, can kill or reduce germination of most weed seeds provided they are not fully mature.

Recommendations for row crops:

  • Corn: 2,4-D, glyphosate, paraquat, and Aim.
  • Soybeans: Glyphosate, dicamba, paraquat, and Aim.
  • Sorghum: Glyphosate and Aim
  • Sunflowers: Paraquat and glyphosate.

Herbicide Resistance Info

Application Considerations

Always use the rate on the label of the product used. With generic products like 2,4-D, dicamba, glyphosate, and paraquat rates vary from product to product. Remember, if glyphosate was used earlier this season and did not control all of the weeds it is unlikely that it will control them now.

Before using any product pre-harvest make sure that the chemical being used is labeled to control the target weeds. Make sure to follow all time restrictions before harvesting the crop. Secondly if forage is going to be used for feed or bedding from the field make sure the application allows for this practice.