It’s time to start planning ahead for fall dandelion management. The Weed Science website at the University of Wisconsin Extension has a thorough description of the dandelion’s life cycle and some suggestions for control. A group of researchers at the University of Wisconsin evaluated fall and spring herbicide applications for control of dandelion in 2011. Their key findings were:

1. Herbicide applications in the fall were most effective for early-season dandelion control compared to applications at normal corn planting in the spring.
2. Applications during the spring were ideal for late-season control when soybean planting occurs.

For specific information on herbicides, please see their slide presentation.

The flowering stage of dandelion is easily identified by most. However, identifying the seedling stage is helpful because management is best before dandelions enter the adult stage. The following plant characteristics will help with identifying seedling dandelions:

• Seed leaves (cotyledons) are oval or spoon-shaped
• First true leaf is ovular and 0.4 inches (1 cm) long. Leaf margins have a few very small teeth that point back toward the base of the leaf. The midvein is prominent on the underside of the leaf.
• Later leaves are more elongated and will have the toothed margins and rosette arrangement typical of the mature plant.

Managing dandelions can either be done through the use of herbicide or physical removal in either the spring or fall. However, dandelions are more susceptible to herbicides applied in the fall. If physical removal is the management mode of choice, it must be done in the spring as well as the fall.

Management options for corn and soybean are listed below.

Corn

Chemical control options:

• Fall application of 2,4-D or dicamba at 1 pint per acre applied alone or as a tank mix prior to the first killing frost. Another option is glyphosate but for optimal activity applications need to be made when the air temperature is above 50 degrees F and the plant is still actively growing.
• Spring applications of 2,4-D ester at 1 pint per acre prior to corn emergence or a tank-mix of 2,4-D with glyphosate will provide some dandelion control. Also, post-emergence applications of growth regulator herbicides typically provide acceptable control.

Mechanical control options:

• Moldboard or chisel plowing will weaken the plant by disturbing the taproot and may make chemical applications more effective.

Soybean

Chemical control options:

• 2,4-D ester may be applied prior to soybean planting if a seven-day interval is observed between application and planting.
• There are no good post-emergence options for dandelion control in soybeans.
• If possible, control heavy infestations of dandelions in the fall if the field is to be planted to no-till soybeans.

References:

1. http://www.extension.psu.edu/pests/weeds/weed-id/common-dandelion, site accessed July 27, 2014.
2. http://www.umanitoba.ca/outreach/naturalagriculture/articles/dandelion.html, site accessed July 27, 2014.
3. http://fyi.uwex.edu/weedsci/2002/11/12/dandelion/, site accessed July 27, 2014.

Authors:

Madeline Fischer and Liz Bosak

Madeline Fischer is an undergraduate research assistant working for WCWS at the Arlington Agricultural Research Station. In Fall 2014, Madeline will be a sophmore pursuing a degree in Life Science Communcations and Environmental Studies.

This article was posted in WCWS and tagged Agriculture, corn, dandelion, fall, farm, herbicide, integrated pest management, integrated weed management, IPM, mechanical control, taraxacum officinale, University of Wisconsin, Weed, Wisconsin.