Giant ragweed is becoming more prevalent across Federated’s trade area. “It is a weed that needs to be controlled early,” said John Swanson, Federated agronomist at the Ogilvie location, “and it is one of the most competitive weeds for our crops.”

The best control for this challenging weed is a pre-emergence herbicide, and in corn “Acuron® with bicyclopyrone (SOA-27) is a great choice,” said Swanson (see article below).

Giant ragweed can be very difficult to control post emerge. “It grows so rapidly and we often do not get it sprayed small enough,” said Swanson. It needs to be sprayed when it is 2-4 inches tall or less.  

Post-emerge options to help control giant ragweed in corn include: 

• Buccaneer® Plus (glyphosate – if it is not resistant),
• Interline™ (glufosinate, SOA-10)
• Callisto® (SOA-27),
• Dicamba products such as Detonate® or Status® (SOA-4), and 
• Stinger® (SOA-4). 

In soybeans, controlling giant ragweed is also best with pre-emerge treatments. “A product containing FirstRate® (SOA-2), such as Sonic® or Authority® First, make great choices,” said Swanson. Some ragweed plants are resistant to ALS herbicides, and if FirstRate doesn’t do the job, according to Swanson, “we may have resistance.”

“If the pressure is moderate to light we can also use a Panther® (SOA-14) and Tricor®4F (SOA-5) tank mix as well,” he said.

Post-emerge options in soybeans include:

• Buccaneer Plus (glyphosate – if it is not resistant),
• Interline (glufosinate, SOA-10),
• Flexstar® (SOA-14),
• Cobra® (SOA-14),
• Xtendimax®, Engenia,® or FeXapan® (on dicamba-resistant soybeans only, SOA-4), and
• FirstRate (SOA-2). 

Swanson emphasized that the “best management practice is to lay down a pre-emergence herbicide and then follow it with a post application when weeds are 2-4 inches in height.”

Discuss giant ragweed control options with your Federated Agronomist soon – before the weeds are popping out of the ground.