Mechanical Weed ManagementMechanical Weed Management

Chuck MohlerChuck Mohler

Cornell UniversityCornell University

Some basic principles of Some basic principles of mechanical weed controlmechanical weed control

In-row weeding is essential! In-row weeding is essential!

Cultivator rows = planter rows (or some Cultivator rows = planter rows (or some nice fraction)nice fraction)– Exceptions – tine weeders & rotary hoesExceptions – tine weeders & rotary hoes

Cultivator must be appropriate for the Cultivator must be appropriate for the growth stage of the weeds and cropgrowth stage of the weeds and crop

Create and maintain a size difference Create and maintain a size difference between weeds and cropbetween weeds and crop

More principlesMore principles

When weeds are very dense, cultivators When weeds are very dense, cultivators take out a smaller fraction of themtake out a smaller fraction of them

Increase planting density to compensate Increase planting density to compensate for stand loss from in-row machinesfor stand loss from in-row machines– Especially in small grainsEspecially in small grains

Good soil drainage helps a lot!Good soil drainage helps a lot!

Chop crop residue if you reduce tillageChop crop residue if you reduce tillage

Create a dust mulchCreate a dust mulch

A row crop cultivator – 5 shanksA row crop cultivator – 5 shanks

Brillion high residue cultivatorBrillion high residue cultivator

No inter-row weedsNo inter-row weeds

How cultivators kill weedsHow cultivators kill weeds

BurialBurial

DismembermentDismemberment– Especially, severing root from shootEspecially, severing root from shoot

Desiccation – want to shake soil free from Desiccation – want to shake soil free from rootsroots

Conditions determine what you Conditions determine what you want to do to the weedswant to do to the weeds

Desiccation only works if soil is going to Desiccation only works if soil is going to dry.dry.

If soil is moist, bury the weedsIf soil is moist, bury the weeds

Cultivation close to a young crop row -- go Cultivation close to a young crop row -- go for severing roots from shootsfor severing roots from shoots

Clean out near-surface weeds Clean out near-surface weeds without harming the cropwithout harming the crop

Germinating crop seeds

Weed seedlings that can reach the surface

Comparison of tine weedersComparison of tine weedersMachineMachine ArmArm ““Tooth”Tooth” Diam.Diam. AngleAngle SpacingSpacing MountingMounting

KovarKovar 15”15”

20”20”

20”20”

StraightStraight

5”5”

3.5”3.5”

5/16 or 1/45/16 or 1/4

5/16 or 1/4 5/16 or 1/4 1/41/4

00

45°45°

80°80°

~ 1.5”~ 1.5” ChainChain

EinbochEinboch ~ 60 °~ 60 ° 1”1” RigidRigid

RabewerkRabewerk 10.5”10.5” 5”5” 1/41/4 45 °45 ° 1”1” Chain +Chain +

LelyLely 15”15” 4.5”4.5” 3/163/16 75 °75 ° 1.6”1.6” RigidRigid

Blind cultivationBlind cultivation

When to tine weedWhen to tine weedCorn – pre-emergence to about 8”Corn – pre-emergence to about 8”– Avoid acute 60Avoid acute 60° to 80 ° tines, especially at ° to 80 ° tines, especially at

spike to 2 leaf stagespike to 2 leaf stage

Soybean, beans – pre-emergence; Soybean, beans – pre-emergence; seedling to 8”seedling to 8”– Avoid crook stage!Avoid crook stage!

Barley, wheat, spelt – pre-emergence; 4 Barley, wheat, spelt – pre-emergence; 4 leaf to stem elongationleaf to stem elongationOat – pre-emergence; 2 leaf to stem Oat – pre-emergence; 2 leaf to stem elongationelongation

Rotary hoeRotary hoe

Minimum Minimum tillage tillage rotary rotary hoehoe

Points about rotary hoeingPoints about rotary hoeing

Crop stages – similar to tine weedersCrop stages – similar to tine weeders

Weeds must be tiny – small window of Weeds must be tiny – small window of opportunityopportunity

Great for breaking crustsGreat for breaking crusts– Break crusts with rotary hoe, then tine weedBreak crusts with rotary hoe, then tine weed

Gauge wheelsGauge wheels

High speed! – 9 to 12 mphHigh speed! – 9 to 12 mph

Tilth matters for cultivation!Tilth matters for cultivation!

Loose soil shakes off of roots betterLoose soil shakes off of roots better

Good tilth allows more uniform coverage Good tilth allows more uniform coverage of weeds in the crop rowof weeds in the crop row

Clods neutralize in-row tools.Clods neutralize in-row tools.

Machines for getting very close Machines for getting very close to or into the crop rowto or into the crop row

Basket weederBasket weeder

Brush hoeBrush hoe

Brush weederBrush weeder

BuddinghBuddingh

EinbochEinboch

Torsion Torsion weederweeder

forward forward motion motion

spreads spreads tipstips

In-row flamingIn-row flaming

Weeds after flamingWeeds after flaming

Energy useEnergy use

SystemSystem WhatWhat Cal/ACal/A %%

Rotary hoe 2X + shovel Rotary hoe 2X + shovel cultivate 2Xcultivate 2X

Diesel onlyDiesel only 57,00057,000 100100

Atrazine + DualAtrazine + Dual Herbicide Herbicide onlyonly

69,00069,000 122122

Roundup 1 qt/ARoundup 1 qt/A Herbicide Herbicide onlyonly

68,00068,000 120120

ConclusionsConclusions

Start with a 45Start with a 45°° tine weeder, and a good tine weeder, and a good row-crop cultivatorrow-crop cultivator

Having more tools around will allow a Having more tools around will allow a better jobbetter job– and save the day in tough situations! and save the day in tough situations!

Adjustments, adjustments, adjustments!Adjustments, adjustments, adjustments!– A hydraulic top link is a good investmentA hydraulic top link is a good investment

For best results – take care of the soil!For best results – take care of the soil!