1. Mechanical Weed Management
Chuck Mohler
Cornell University

2. Outline Basic principles of cultivation
Row crop cultivators and how to use them
In-row weeding with tine weeders and rotary hoes
Importance of good tilth for cultivation
Machines that work very close to the row
Closing remarks

3. Some basic principles of mechanical weed control
In-row weeding is essential!
Cultivator rows = planter rows (or some nice fraction)
Exceptions – tine weeders & rotary hoes
Cultivator must be appropriate for the growth stage of the weeds and crop
Create and maintain a size difference between weeds and crop

4. More principles
When weeds are very dense, cultivators take out a smaller fraction of them
Increase planting density to compensate for stand loss from in-row machines
Especially in small grains
Good soil drainage helps a lot!
Chop crop residue if you reduce tillage
Create a dust mulch

5. A row crop cultivator – 5 shanks

6. At lay-by cultivation

7. Rolling cultivators need sweeps!

8. A high residue cultivator – 1 shank + a coulter + disk hillers

9. No inter-row weeds

12. How cultivators kill weeds
Burial
Dismemberment
Especially, severing root from shoot
Desiccation – want to shake soil free from roots

13. Conditions determine what you want to do to the weeds
Desiccation only works if soil is going to dry.
If soil will remain moist, bury the weeds
Cultivation close to a young crop row -- go for severing roots from shoots

14. Clean out near-surface weeds without harming the crop

18. Comparison of tine weeders
Machine
Arm
“Tooth”
Diam.
Angle
Spacing
Mounting
Kovar
15”
20”
Straight 5”
3.5”
5/16 or 1/4
5/16 or 1/4 1/4
45°
80°
~ 1.5”
Chain
Einbock
~ 60 ° 1”
Rigid
Rabewerk
10.5”
1/4
45 °
Chain +
plate
Lely
4.5”
3/16
75 °
1.6”

19. Three ways to adjust aggressiveness of a tine weeder
Tine angle
Gauge wheels
Speed

20. Blind cultivation

22. When to tine weed Corn – pre-emergence to about 8”
Avoid acute 60° to 80 ° tines, especially at spike to 2 leaf stage
Soybean, beans – pre-emergence; seedling to 8”
Avoid crook stage!
Barley, wheat, spelt – pre-emergence; 4 leaf to stem elongation
Oat – pre-emergence; 2 leaf to stem elongation

23. Rotary hoe

24. Minimum tillage rotary hoe

25. Points about rotary hoeing
Crop stages – similar to tine weeders
Weeds must be tiny – small window of opportunity
Great for breaking crusts
Break crusts with rotary hoe, then tine weed
Gauge wheels
High speed! – 9 to 12 mph

26. Tilth matters for cultivation!
Loose soil shakes off of roots better
Good tilth allows more uniform coverage of weeds in the crop row

27. Clods neutralize in-row tools.

28. Machines for getting very close to or into the crop row
These machines require careful guidance
Usually requires belly mounting or a second person to steer

29. Basket weeder

30. Brush hoe

32. Brush weeder

33. Buddingh finger weeder

34. Einbock

35. Wiggle hoe

36. Regi Eco Weeder

37. In-row flaming

38. Weeds after flaming

39. Flaming beds

40. Torsion weeder forward motion spreads tips

41. Spyders and spring hoes

42. Energy use System What Cal/A % Rotary hoe 2X + shovel cultivate 2X
Diesel only
57,000
100
Atrazine + Dual
Herbicide only
69,000
122
Roundup 1 qt/A
68,000
120

43. Recomendations
Start with a 45° tine weeder, and a good row-crop cultivator
Having more tools around will allow a better job
and save the day in tough situations!
Adjustments, adjustments, adjustments!
A hydraulic top link is a good investment
For best results – take care of the soil!