Weed Control for Seed Growers in Direct Seeding Systems
Neil Harker
Agriculture and Agri-Food Canada
Lacombe Research Centre
Lacombe, AB
Can I Be a Seed Grower and Direct Seed?
What is Different?
- More volunteers - primary challenge
- Dependence on glyphosate burn-off treatment
-
- all volunteers will not emerge before burn-off
- Some HT Canola volunteers may escape burn-off
treatment
-
- keep good field records
- tank-mix glyphosate with a phenoxy
- No pre-harvest glyphosate on seed crops
What Can be Done?
- Volunteers
-
- replant same variety year after year
-
- the current variety registration system is not
helping
- 30-40 new varieties with few important
differences
- frustration of guessing which variety will be
popular
- spend some time changing the system so that only
significant improvements Þ new varieties
- avoid semi-dwarfs (tend to have higher dormancy)
- extend rotations (ß volunteers and diseases)
- make arrangements to exchange land with neighbours
(broken hay land - grow Foundation)
- fall harrowing immediately after harvest
-
- also good for straw and chaff management
- but watch for dandelions and winter annuals
Pre-harvest Glyphosate Acres Treated - W. Canada

What Can be Done?
- Pre-harvest glyphosate in non-seed years
-
- need to get it into the system for perennial weeds
- Agronomic Management of Weeds
-
- use silage, forages and winter crops if possible, i.e.,
diversify the rotation to keep weeds off balance
- chaff collection (Martin Entz - U of Man.)
- Weed Management Research at Lacombe
-
- plant competitive varieties (avoid
semi-dwarfs)*
- increase crop seeding rate*
- reduce weeds with early-cut barley silage*
Barley Variety Effects on Wild Oat
Wild Oat Biomass - 1997

Barley Yields - 1997
Optimal Cropping Systems - Effects on Weeds
- Objective:
-
- Combine several agronomic factors at optimal levels as
the first level of management against weeds - herbicides
are 2° consideration
- Materials and Methods
-
- Barley/Pea Rotation
- Early & normal seeding dates
- 1 and 1.5X seeding rates
- Fall- versus Spring-banded fertilizer
- 0 and 1/2 herbicide rates (change to 1/3 and 2/3)
Seeding Rate and Herbicide Rate
Cleavers dry wt. - Barley

Seeding Rate and Herbicide Rate
Barley Yield

Barley Silaging Effects on Wild Oat Populations
- Objective:
-
- Assess wild oat populations after early- (heads fully
emerged) and normal-cut (soft dough) barley silage versus
barley grain production
- Materials and Methods
-
- add 1/2 rates of wild oat herbicide to silage
production systems
- Conduct experiments at same site each year: assess wild
oat population dynamics after several years in the silage
or grain system
Treatment List
- 1. Barley grain - no herbicide
- 2. Early-cut barley silage - no herbicide
- 3. Normal-cut barley silage - no herbicide
- 4. Barley grain - Assert (1/2)
- 5. Barley grain - Assert (1)
- 6. Barley grain - Achieve (1/2)
- 7. Barley grain - Achieve (1)
- 8. Early-cut barley silage - Assert (1/2)
- 9. Early-cut barley silage - Achieve (1/2)
- 10. Normal-cut barley silage - Assert (1/2)
- 11. Normal-cut barley silage - Achieve (1/2)
97 Wild Oat Emergence
(#/m2)
98 Wild Oat Emergence
(#/m2)

Summary
- Extended Rotations with extra Diversity
- Fall Harrowing - volunteers
- Good Agronomics
- Early-cut silage for weed management