Attendees will gain a basic understanding of the processes influencing herbicide availability which is essential to diagnose performance issues in the field.
13. Keys to Resistant
Weed Management
• Know your enemy
• Optimize herbicide effectiveness
14. Evolution of Herbicide Rates
Full label rate Acetochlor Flumetsulam Clopyralid
Pre RR 3 pts Harness + 2.6 lbs 0.9 oz 2.5 oz
5 oz Hornet
Post RR 2 pts SureStart 36% 50% 50%
Post RRv2.0 3 pts SureStart 54% 75% 75%
% herbicide remaining
Waterhemp emergence
# emerged/week
April May June July
15. Keys to Resistant
Weed Management
• Cultural practices
– Manipulation of cropping conditions to
reduce the density and competitiveness of
weeds
or
16. Effects of Cultural Practices
in Nebraska Wheat Fields
Row Direction Drill Type
E-W N-S Disk Hoe
40 6
30
4
20
2
10
0 0
LQ Pig Grass Fox Kochia Stinkgrass 8 Others
Wicks et al. 2003. Weed Technol.
20. Cultural Practices For
An Herbicide Era
• Row spacing
• Planting rate
• Planting date
• Variety characteristics
21. Herbicide Resistance
• Weeds adapt to all tactics, all herbicides
• The greater the reliance on a tactic, the
greater the speed of adaption
• Integrated management programs
needed to stay ahead of evolution