Broadleaf Weed Control in Maize and Sorghum

Broadleaf weeds in maize cause significant yield losses through competition for water, nutrients, and light. Species such as black nightshade (Solanum nigrum), blackjack (Bidens pilosa), pigweed (Amaranthus hybridus), fat hen (Chenopodium album), and wild mustard (Sinapis arvensis) are the most economically important in Southern Africa.

Critical Weed-Free Period

Maize must remain free of broadleaf weeds for the first 6 weeks after planting (3-leaf to 6-leaf stage). Broadleaf weeds establishing after this point generally have less impact on final yield.

Pre-Emergence Control

Post-Emergence Control in Maize

Application Guidelines

• •Apply 2,4-D and dicamba only within the specified crop growth stage window — outside this window, severe crop damage occurs
• •Avoid applying dicamba in hot, humid conditions or when adjacent sensitive crops could be affected by vapour drift
• •Use flat fan nozzles for uniform coverage; avoid fine mist nozzles that increase drift risk
• •Apply when weeds are actively growing (2–4 leaf stage for best results)

Resistance Alert

Glyphosate-resistant populations of blackjack and other broadleaf weeds have been confirmed in parts of Southern Africa. Rotate herbicide modes of action and avoid over-reliance on glyphosate in minimum tillage systems.