Fight back against weeds in your soybeans this season

By Blake Jackson

Recent rains have spurred weed growth in Pennsylvania soybean fields, making weed control a critical focus. Here's a summary of key considerations for soybean farmers:

Palmer Amaranth and Waterhemp: These pigweed species are spreading rapidly. Early scouting is crucial to identify the pigweed type for effective management. Aim to control them before they reach 4 inches, as larger plants are much harder to eliminate.

Herbicide Options:

• XtendFlex or Enlist Soybean Systems: These offer excellent control.
• Glyphosate-Based System: Consider adding a Group 14 herbicide (Reflex, Cobra, Ultra Blazer) and a Group 15 herbicide (Zidua/Anthem Maxx/Perpetuo, Dual/Prefix, Warrant/Warrant Ultra) for residual control.
• Liberty (Glufosinate): Effective control in LibertyLink, Enlist E3, or XtendFlex varieties. Research shows a tank mix of Liberty and Enlist One in E3 soybeans provides excellent control.

Marestail: There are ALS- and glyphosate-resistant marestail populations in Pennsylvania.

• LibertyLink Varieties: Use glufosinate (Liberty) at a high rate for control. Tank-mixing with 2,4-D choline (Enlist One/Duo) in E3 or Xtendimax, Engenia, Tavium in Xtend varieties can improve control.
• Non-ALS-Resistant Marestail: FirstRate can still be effective.
• Roundup Ready System: A double dose of glyphosate or multiple in-crop applications can suppress marestail. Early treatment is crucial.

Volunteer Corn: Glyphosate-resistant and glufosinate-resistant volunteer corn is common. Use post-emergence grass herbicides like Assure II, Select, clethodim, or Fusilade for control. Always include the appropriate adjuvants (crop oil concentrate, methylated seed oil) for optimal results.

Important Dates:

• XtendiMax, Engenia, Tavium: Application cut-off for Xtend/XtendFlex soybeans is June 30th.
• Enlist Products: Applicable to Enlist E3 soybeans through R1 (flower initiation) growth stage.

Alternative Herbicides (post June 30th): Glyphosate, glufosinate, Pursuit, Raptor, Classic, FirstRate, Reflex/Flexstar, Cobra, Ultra Blazer (all have application timing restrictions).

Remember to consult herbicide labels for specific rates, application instructions, and pre-harvest intervals. By following these guidelines and scouting fields regularly, Pennsylvania soybean farmers can effectively manage weeds and ensure a successful harvest.

Photo Credit: istock-sandramatic