Post on 27-Apr-2020
1
Mechanical Weed Control in Organic Crops
Eric N. Johnson1 and Steven J. Shirtliffe1Agriculture and Agri-Food Canada, Scott, SK
2
EWRS
3
Hand weeding intra-row weeds:
200-500 hours per hectare in carrot and direct sown onion and leek
DIAS
4
Mechanical Weed Control Research in Saskatchewan
• Pre-seeding tillage• Pre-emergence tillage
– Rod-weeder, harrow, rotary hoe, small shovels on heavy harrow
• Post-emergence – Harrows, rotary hoe– Inter-row cultivation– Mowing, rolling, weed clipping– Alternative cropping study – long-term study
5 6
Pre-seeding tillage
2
7
Interaction of Seed Date and Flax Cultivar on Yield. Mean of 2 sites (Saskatoon, Scott). 2003
0200400600800
10001200140016001800
May 15 June 1 June 15
Seed Date
kg h
a-1
BethuneVimyNormandyLine 6Line 5
Seed Date X Cultivar interactionp < 0.01
8
Effect of seeding date and weed management on weed biomass in flax. Scott and Saskatoon, SK 2003-2005.
0.0
50.0
100.0
150.0
200.0
250.0
300.0
350.0
May 15 June 1 June 15
Seeding Date
g/sq
.m.
Pre-seed tillage Pre-seed burnoff Pre-seed burnoff + in-crop herbicide
9
0
200
400
600
800
1000
1200
1400
May 15 June 1 June 15
Seeding Date
kg/h
a
Pre-seed tillage Pre-seed burnoff Pre-seed burnoff + in-crop herbicide
Effect of seeding date and weed management on yield of flax. Scott and Saskatoon, SK 2003-2005.
~70%
10
Post-seeding / Pre-emergenceTillage in field pea
MECHANICAL WEED CONTROL RESEARCH IN SASKATCHEWAN
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Questions
• Seed shallow and compete ??• Seed deep / pre-emerge till ??• Seed early?? Seed late ??
12
Interaction of Seeding Date, Seed Depth/Tillage System on Weed Biomass in Field Pea. Scott 1999-2001.
0100200300400500600700800900
1000
Wd
biom
ass
(g/m
2)
Check Harrow Rod Wd
Early May
HerbicideEarly
2.5 7.5 2.5 7.5 2.5 7.5Mid May Late May
3
13
Effect of Seeding Date, Seed Depth/Tillage System on Field Pea Yield. Scott 1999-2001.
0
500
1000
1500
2000
2500
3000
3500
Yiel
d (k
g/ha
)
Check Harrow Rod Wd
Early May2.5 7.5 2.5 7.5 2.5 7.5
Mid May Late May
HerbicideEarly
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Field pea seeded May 4 3” depth - Herbicide
Field pea seeded May 18 3” depth - Pre-emergence rod-
weed
If timed properly, pre-emergence tillage can be effectivein large seeded crops
•The best seed date X seed depth/pre-emergence tillage combination resulted in 80% of the yield obtained with the best seed date/ seed depth/ herbicide combination.
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Maintenance ofCrop Residues
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17 18
Effect of rotary hoe passes on the maintenance of cereal stubble residue, Scott, SK. 2004 - 06.
No. of passes % surface residue0 641 612 584 615 566 55
LSD0.05 12CV 13
No Rotary Hoe
6 passes - Rotary Hoe
Rotary hoeing done after seedingbut prior to field pea emergence
4
19
Effect of number of passes from rotary hoeing on field pea and lentil density at two growth stages. Weed-free conditions. Scott 2004-06
0
20
40
60
80
100
Pre-emergence Ground-crack Pre-emergence Ground-crack
Plan
ts/m
2
0 1 2 3 4 5 6
Field Pea Lentil
20
Effect of number of passes from rotary hoeing on field pea and lentil density at two growth stages. Weed-free conditions. Scott 2004-06
0
10
20
30
40
50
Pre-emergence Ground-crack Pre-emergence Ground-crack
Yiel
d (b
u/ac
re)
0 1 2 3 4 5 6
Field Pea Lentil
21
Pre-emergence Rotary hoe
Check 1 pass 2 pass
4 pass3 pass 5 pass22
Heavy harrow shovel – Proof of Concept Study
23
Heavy Harrow / Small Shovels Proof of Concept
• Unreplicated strip trials in fallow and stubble• Stubble had moderate amounts of trash• Seeded to field pea• Treatments
– Untreated– Single Pass Till 5 DAS– Double Pass Till 5 DAS– Single Pass Till + Single Pass Rotary Hoe 5 DAS– Double Pass Rotary Hoe 5 DAS– Single Pass Till Ground Crack– Single Pass Till 3-node
24
Pre-emergence Tillage With Small Shovels – Field Pea Density Scott 2008
0102030405060708090
100
Unt
reat
ed
SP T
ill 5
DA
S
DP
Till
5 D
AS
SP T
ill, S
P R
. Hoe
5 D
AS
DP
R. H
oe 5
DA
S
SP T
ill G
. Cra
ck
SP T
ill 3
Nod
e
Plan
ts/m
2
Stubble
0102030405060708090
100
Unt
reat
ed
SP T
ill 5
DA
S
DP
Till
5 D
AS
SP T
ill, S
P R
. Hoe
5 D
AS
DP
R. H
oe 5
DA
S
SP T
ill G
. Cra
ck
SP T
ill 3
Nod
e
Fallow
5
25
Pre-emergence Tillage With Small Shovels – Field Pea Yield Scott 2008
010203040506070
Unt
reat
ed
SP T
ill 5
DA
S
DP
Till
5 D
AS
SP T
ill, S
P R
. Hoe
5 D
AS
DP
R. H
oe 5
DA
S
SP T
ill G
. Cra
ck
SP T
ill 3
Nod
e
bus/
acre
Stubble Fallow
010203040506070
Unt
reat
ed
SP T
ill 5
DA
S
DP
Till
5 D
AS
SP T
ill, S
P R
. Hoe
5 D
AS
DP
R. H
oe 5
DA
S
SP T
ill G
. Cra
ck
SP T
ill 3
Nod
e
26
Pre-emergence Tillage With Small Shovels – Field Pea Yield Scott 2008
0
10
20
30
40
50
Unt
reat
ed
SP T
ill 5
DA
S
DP
Till
5 D
AS
SP T
ill, S
P R
. Hoe
5 D
AS
DP
R. H
oe 5
DA
S
SP T
ill G
. Cra
ck
SP T
ill 3
Nod
e
% d
ocka
ge
Stubble Fallow
0
10
20
30
40
50
Unt
reat
ed
SP T
ill 5
DA
S
DP
Till
5 D
AS
SP T
ill, S
P R
. Hoe
5 D
AS
DP
R. H
oe 5
DA
S
SP T
ill G
. Cra
ck
SP T
ill 3
Nod
e
27
Tilling at 3-node stage
28
Post-emergence Tillage
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Selectivity of Harrow Types
Tine Rotary
Flex-Tine Lely
Flex-Tine Einbock
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Mechanical In-Crop Weed Control Selectivity
• Selectivity
– differential tolerance in plant species.
– Ratio between weed control and crop damage
• Selectivity dependent on:
– How closely weeds resemble the crop
– length of seed germination period
– ineffective - perennial weeds
6
31
Relationship between crop burial and yield of field pea from post-emergence harrowing at 3 above-ground node stage. Weedy conditions. Scott 2004 & 2006.
y = -3.8378x3 + 4.6535x2 - 0.7566x + 1.0213R2 = 0.6236
0%
20%
40%
60%
80%
100%
120%
140%
160%
180%
0% 20% 40% 60% 80% 100% 120%
Crop burial (%)
Fiel
d pe
a yi
eld
(% o
f che
ck)
32
1999
Harrow Type / SettingTine low Tine high Rot. low Rot. high
0
20
40
60
80
100
..................................................................................................................................
single harrow double harrow
Fie l
d p e
a de
n sity
(pl
ants
m-2
)
Untreated
33
Effect of harrow type and disturbance level on wild oat fresh weight (g m-2), Scott, 1999
0100200300400500600
Tine Low Tine High Rotary Low RotaryHigh
Untreated
Harrow Type
g m
-2
10° back
High45° back
Low
34
Crop Tolerance to Post-Emergence Harrowing
• Crop tolerance is composed of two factors:
– Resistance: the ability of the crop to resist soil covering;
– Recovery: the ability of the crop to recover from soil covering.
35
Crop burial of barley, oat and wheat (from left to right) after four passes at the two leaf stage. Averaged over all treatments, crop burial of wheat (57%) was significantly greater (P<0.05) than barley (44%) and oat (38%).
Oat and barley had higher resistance to crop burial
than wheat
36
Effect of timing of post-emergence harrowing on crop burial – mean of oats, barley, and wheat. Scott/ Saskatoon
y = 5.8834x + 59.129R2 = 0.9318
y = 6.4145x + 17.746R2 = 0.9989
y = 2.1129x + 5.8R2 = 0.8764
0
10
20
30
40
50
60
70
80
90
100
0 1 2 3 4 5 6 7
Number of Harrow Passes
Estim
ated
Cro
p B
uria
l (%
)
2 4 6
Leaf stage
y = 5.8834x + 59.129R2 = 0.9318
y = 6.4145x + 17.746R2 = 0.9989
y = 2.1129x + 5.8R2 = 0.8764
0
10
20
30
40
50
60
70
80
90
100
0 1 2 3 4 5 6 7
Number of Harrow Passes
Estim
ated
Cro
p B
uria
l (%
)
2 4 6
Leaf stage
Later growth stages had higher resistance to crop
burial
7
37
Effect of post-emergence harrowing on yields of oats, barley, and wheat relative to untreated checks. Weed-free conditions.
Scott/ Saskatoon
Wheat had poorer recovery than oat and barley
(as well as resistance)Later growth stages had
better resistance but poorer recovery
(oats and barley) 38
Post-emergence rotary hoeing
39
2- year study at Scott
• Field pea• Treatments
– Untreated– Single Pass – Ground Crack stage (1)– Double Pass – Ground Crack stage (2)– Triple Pass – Group Crack stage (3)– Single Pass – Ground Crack + 3-node stage (2)– Double Pass – Ground Crack + 3-node stage (4)– Triple Pass – Ground Crack + 3-node stage (6)– Single Pass – Ground-Crack + 3-node + 5-node stage (3)– Double Pass – Ground-Crack + 3-node + 5-node stage (6)– Triple Pass – Ground-Crack + 3-node + 5-node stage (9)
( ) Total passes
40
Rotary Hoe – Effect on Field Pea Density Scott 2007 + 2008
0102030405060708090
100
0 1 2 3 4Number of Passes
Plan
ts (#
/m2)
Ground CrackGround Crack + 3 NodeGround Crack + 3 Node + 5 Node
41
Rotary Hoeing – Effect on Weed Biomass
0
100
200
300
400
500
600
700
0 1 2 3 4Number of Passes
Wee
d Fr
esh
Wei
ght (
g/m
2)
Ground CrackGround Crack + 3 NodeGround Crack + 3 Node + 5 Node
Herbicide
42
Rotary Hoeing – Effect on Field Pea Yield
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
0 1 2 3 4Number of Passes with Rotary Hoe
Yie
ld (b
u/ac
re)
Ground CrackGround Crack + 3 NodeGround Crack + 3 Node + 5 Node
Herbicide Treatment
8
43
Rotary Hoeing
• 4 – 6 passes is a lot!• Only done by crazy
scientists!
Pre-emerge
+
Post-emerge
= ??
44
Inter-row Cultivation
45
Inter-row cultivation - benefits limited by in-row weed competition
46
Integration of Mechanical Weed Control MethodsPre-emerge rod-weed X post-emerge harrow X inter-row cultivation
Untreated
Pre-emerge rod-weed, cross-harrow and inter-row cultivate
47
Yield Response from Pre-Emergence Rod-Weed, Post-emergence Harrow, and Inter-row Cultivation. Mean of 3 years, Scott (2000, 2001 and 2003)
NSInter-row Cultivation
2.0Post-Emergence Harrowing
5.9Pre-Emergence Rod- Weed
Bu/acre
48
Interaction of Pre-Emergence Rod-Weed and Inter-row Cultivation on Yield of Field Pea, Scott, Mean of 3 years (2000, 2001, 2003)
0
5
10
15
20
25
30
No PE Rod Wd PE Rod Wd
bu a
cre-1
0 Harrow 1 IR Cult 2 IR Cult
9
49
Weed Clipping
50
05
1015202530354045
Wee
dy
Her
bici
de 400
550
700
Con
tinuo
us
Wild
oat
see
dlin
gs /
m2
GDD0.05
Effect of clipping on wild oat seedling recruitment. Mean of 2 years. Scott 2007
No weed clipping Weed clipping
52
0
20
40
60
80
100
Check Tine Lely-Low Lely-Mod Lely-High
plan
ts m
-2
1 2 3 4
* * * * * * *
* Statistically lower than the herbicide check at P<0.05
Harrow Type
53
Effect of harrow passes on weed biomass. Mean of 4 harrow settings. Scott. 1999-2001
0100200300400500600700800900
Check 1 2 3 4
No of Passses
Wee
d bi
omas
s (g
/m2) 0.47 0.32
0.060.03
Numbers represent p values for contrasts vs. check
54
Effect of harrow passes on weed biomass. Mean of 4 harrow settings. Scott. 1999-2001
00.5
11.5
22.5
33.5
Untreated Herbicide Tine Lely-Low Lely-Mod Lely-High
Yiel
d (t
/ha)
1 2 3 4
* * * * **
10
55
Rotary Harrow – Soil Disturbance Settings
45°
45°Harrow
High15°
Harrow
Low
15°
56
Untreated Single Harrow 3Xemg, 3 & 5 lf
Double Harrow 3Xemg, 3 & 5 lf
Herbicide