Mechanical Weed Control in Organic Crops

Transcription

1 EWRS Mechanical Weed Control in Organic Crops Eric N. Johnson 1 and Steven J. Shirtliffe 1 Agriculture and Agri-Food Canada, Scott, SK 2 Mechanical Weed Control Research in Saskatchewan DIAS Hand weeding intra-row weeds: -5 hours per hectare in carrot and direct sown onion and leek 3 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 4 Pre-seeding tillage 5 6 1

2 Interaction of Seed Date and Flax Cultivar on Yield. Mean of 2 sites (Saskatoon, Scott). 3 Effect of seeding date and weed management on weed biomass in flax. Scott and Saskatoon, SK 3-5. kg ha May 15 June 1 June 15 Seed Date Seed Date X Cultivar interaction p <.1 Bethune Vimy Normandy Line 6 Line 5 g/sq.m. Pre-seed tillage Pre-seed burnoff Pre-seed burnoff + in-crop herbicide May 15 June 1 June 15 Seeding Date 7 8 Effect of seeding date and weed management on yield of flax. Scott and Saskatoon, SK Pre-seed tillage Pre-seed burnoff Pre-seed burnoff + in-crop herbicide ~7% MECHANICAL WEED CONTROL RESEARCH IN SASKATCHEWAN Post-seeding / Pre-emergence Tillage in field pea kg/ha 8 May 15 June 1 June 15 Seeding Date 9 1 Interaction of Seeding Date, Seed Depth/Tillage System on Weed Biomass in Field Pea. Scott Questions Check Harrow Rod Wd 1 Seed shallow and compete?? Seed deep / pre-emerge till?? Seed early?? Seed late?? Wd biomass (g/m2) Early 11 Early May Mid May Late May 12 2

3 Yield (kg/ha) Effect of Seeding Date, Seed Depth/Tillage System on Field Pea Yield. Scott Check Harrow Rod Wd Early If timed properly, pre-emergence tillage can be effective in large seeded crops Field pea seeded May 4 3 depth - The best seed date X seed depth/pre-emergence tillage combination resulted in 8% of the yield obtained with the best seed date/ seed depth/ herbicide combination Early May Mid May Late May 13 Field pea seeded May 18 3 depth - Pre-emergence rodweed 14 Maintenance of Crop Residues Effect of rotary hoe passes on the maintenance of cereal stubble residue, Scott, SK No Rotary Hoe No. of passes % surface residue LSD.5 12 CV 13 6 passes - Rotary Hoe Rotary hoeing done after seeding but prior to field pea emergence

4 Effect of number of passes from rotary hoeing on field pea and lentil density at two growth stages. Weed-free conditions. Scott 4-6 Effect of number of passes from rotary hoeing on field pea and lentil density at two growth stages. Weed-free conditions. Scott Plants/m Yield (bu/acre) Pre-emergence Ground-crack Pre-emergence Ground-crack Field Pea Lentil Pre-emergence Ground-crack Pre-emergence Ground-crack Field Pea Lentil 19 2 Pre-emergence Rotary hoe Heavy harrow shovel Proof of Concept Study Check 1 pass 2 pass 3 pass 4 pass 5 pass Heavy Harrow / Small Shovels Proof of Concept Pre-emergence Tillage With Small Shovels Field Pea Density Scott 8 Unreplicated strip trials in fallow and stubble Stubble had moderate amounts of trash Seeded to field pea Treatments 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 23 Plants/m Stubble Fallow 24 4

5 Pre-emergence Tillage With Small Shovels Field Pea Yield Scott 8 Pre-emergence Tillage With Small Shovels Field Pea Yield Scott 8 Stubble Fallow Stubble Fallow bus/acre % dockage Tilling at 3-node stage Post-emergence Tillage Flex-Tine Lely Selectivity of Harrow Types Mechanical In-Crop Weed Control Selectivity Flex-Tine Einbock Tine Rotary 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 Relationship between crop burial and yield of field pea from post-emergence harrowing at 3 above-ground node stage. Weedy conditions. Scott 4 & 6. single harrow double harrow Field pea yield (% of check) 18% 16% 14% 12% 1% 8% 6% 4% 2% y = x x x R 2 =.6236 % % 2% 4% 6% 8% 1% 12% Crop burial (%) 31 Field pea density (plants m -2 ) Tine low Tine high Rot. low Rot. high Harrow Type / Setting 32 Effect of harrow type and disturbance level on wild oat fresh weight (g m -2 ), Scott, 1999 Crop Tolerance to Post-Emergence Harrowing g m Tine Low Tine High Rotary Low Rotary High 1 back High Harrow Type 45 back Low 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 Effect of timing of post-emergence harrowing on crop burial mean of oats, barley, and wheat. Scott/ Saskatoon Oat and barley had higher resistance to crop burial than wheat 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<.5) than barley (44%) and oat (38%). 35 Estimated Crop Burial (%) 1 y = x R 2 = Later growth stages had 6 y = x higher Leaf stage resistance 5 R 2 =.9989 to crop burial y = x R 2 = Number of Harrow Passes 36 6

7 Effect of post-emergence harrowing on yields of oats, barley, and wheat relative to untreated checks. Weed-free conditions. Scott/ Saskatoon Post-emergence rotary hoeing Wheat had poorer recovery than oat and barley (as well as resistance) Later growth stages had better resistance but poorer recovery (oats and barley) year study at Scott Rotary Hoe Effect on Field Pea Density Scott Field pea Treatments 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 39 Plants (#/m2) Ground Crack 1 Ground Crack + 3 Node Ground Crack + 3 Node + 5 Node Number of Passes 4 Rotary Hoeing Effect on Weed Biomass Rotary Hoeing Effect on Field Pea Yield Weed Fresh Weight (g/m2) Ground Crack Ground Crack + 3 Node Ground Crack + 3 Node + 5 Node Number of Passes Yield (bu/acre) Ground Crack Ground Crack + 3 Node Ground Crack + 3 Node + 5 Node Treatment Number of Passes with Rotary Hoe 42 7

8 Rotary Hoeing 4 6 passes is a lot! Only done by crazy scientists! Inter-row Cultivation Pre-emerge + =?? Post-emerge Inter-row cultivation - benefits limited by in-row weed competition Integration of Mechanical Weed Control Methods Pre-emerge rod-weed X post-emerge harrow X inter-row cultivation Pre-emerge rod-weed, crossharrow and inter-row cultivate Yield Response from Pre-Emergence Rod-Weed, Post-emergence Harrow, and Inter-row Cultivation. Mean of 3 years, Scott (, 1 and 3) Interaction of Pre-Emergence Rod-Weed and Inter-row Cultivation on Yield of Field Pea, Scott, Mean of 3 years (, 1, 3) Bu/acre 3 25 Harrow 1 IR Cult 2 IR Cult Pre-Emergence Rod- Weed Post-Emergence Harrowing bu acre Inter-row Cultivation NS No PE Rod Wd PE Rod Wd

9 Weed Clipping Effect of clipping on wild oat seedling recruitment. Mean of 2 years. Scott 7 Wild oat seedlings / m2 No 45 weed clipping Weed clipping Weedy 55 GDD.5 7 Continuous * Statistically lower than the herbicide check at P<.5 plants m * * * * * * * Check Tine Lely-Low Lely-Mod Lely-High Harrow Type 52 Effect of harrow passes on weed biomass. Mean of 4 harrow settings. Scott Effect of harrow passes on weed biomass. Mean of 4 harrow settings. Scott Weed biomass (g/m2) Numbers represent p values for contrasts vs. check Check Yield (t/ha) * * * * * * Tine Lely-Low Lely-Mod Lely-High No of Passses

10 Rotary Harrow Soil Disturbance Settings Low 15 Harrow High Single Harrow 3X emg, 3 & 5 lf Double Harrow 3X emg, 3 & 5 lf Harrow