Setting Up for a Clean, Profitable Growing Season Next Year
A well-planned fall herbicide program is often one of the highest return weed control investments available to Ontario growers. Whether you’re preparing ground for corn and soybeans or managing winter wheat, fall applications target weeds when they are most vulnerable and can significantly simplify spring management. Controlling winter annuals, biennials, and perennial weeds in the fall improves spring field conditions and reduces early-season crop competition.
Why Consider a Fall Herbicide Program?
- Easier Control of Problem Weeds
Many troublesome weeds are small rosettes in the fall and are much easier to kill than in spring.
Key targets include:
- Canada fleabane (marestail)
- Chickweed
- Shepherd’s-purse
- Field pennycress
- Henbit
- Purple deadnettle
- Dandelion
- Canada thistle
- Field bindweed
Fall-germinating weeds can become large and difficult to manage by planting season if left untreated. Canada fleabane is particularly susceptible at the seedling and rosette stage during fall growth.
- Better Perennial Weed Control
In the fall perennial weeds are moving carbohydrates and nutrients into their roots to prepare for winter. Herbicides applied during this period move with the plant’s natural transport system into roots and underground structures, often providing more complete control than spring applications.
Best examples:
- Dandelion
- Canada thistle
- Milkweed
- Field bindweed
- Cleaner Fields Next Spring
Fall burndown helps:
- Reduce spring weed biomass
- Improve seedbed conditions
- Allow faster soil warming
- Facilitate timely planting
- Improve pre-plant weed control effectiveness
Timing Recommendations
Ontario growers generally achieve the best results when:
- Weeds are actively growing
- Daytime temperatures remain above 8-10°C
- Several hours of favorable conditions follow application
- Applications occur after harvest but before hard freeze-up
For winter annual weeds, late October through November often provides an excellent control window.
Ontario Fall Burndown Excellent Prior to IP Soybeans
Most burndown programs are built around:
Glyphosate-based programs
Effective on:
- Dandelions
- Perennials
- Volunteer cereals
- Many annual weeds
Glyphosate + 2,4-D
Often considered the Ontario standard for many fields because it broadens control and improves activity on difficult broadleaf weeds.
Glyphosate + Dicamba
Useful where:
- Fleabane pressure exists
- Broadleaf weed spectrum is diverse
Observe all crop rotation and plant-back restrictions.
Fall Herbicides in Winter Wheat
Winter wheat offers one of the strongest opportunities to reduce whole-farm weed pressure.
Why Fall Treatment in Wheat?
Many growers wait until spring. However, fall applications can be advantageous where:
- Chickweed is heavy
- Fleabane is present
- Volunteer canola exists
- Shepherd’s-purse is abundant
- Deadnettle or henbit pressure exists
Smaller weeds are generally easier to control and may be eliminated before competing with wheat in spring.
Advantages of Fall Herbicides in Winter Wheat
Better Early Weed Control
Removing weeds early can:
- Protect tillering
- Improve stand uniformity
- Reduce spring competition
Reduced Spring Workload
Spring often compresses:
- Nitrogen applications
- Fungicides
- Planting operations
Fall weed control removes one management task from the busiest season. Also reduces the concerns over cold spring temperature when tank-mixing multiple products.
Improved Yield Protection
During critical spring growth stages winter annual weeds can compete for:
- Moisture
- Nutrients
- Light
