Weed Control for Certified Organic Farmers

1. Weed Control
For
Certified Organic Farmers
Tom Lanini
University of California, Davis

2. Organic Weed Control
•
•
•
•
•
Mulches
Water management
g
Cultivation
Flamers
Organic Herbicides

3. Mulches
• Act by blocking light
• Numerous organic and
synthetic materials can be used
th ti
t i l
b
d
for this purpose

4. Seedlin emerg
ng
gence (N
No./m2)
Seedling Emergence
relative to Light
Dark
600
500
400
300
200
100
0
Light
Light + Glass

12. String trimmer damage??
Rodents???

14. Lumite
Mulch
M l h
Wood chip
p
Mulch

15. Water Management

18. Preirrigation for weed seed
reduction prior to crop planting
d i
i
l i
Questions:
• Is furrow irrigation any different than
sprinkler irrigation as a preirrigation
method
• H
How l
long should you wait after
h ld
it ft
preirrigation before weed removal
• What is the most effective method of weed
removal – flamer or cultivation

19. Hand Weeding Time as Affected
by Preirrigation and Weed
by Preirrigation and Weed
Removal Timing and Method
g
H
Hand wee
eding time (min/plo
e
ot)
7 Day wait
14 Day wait
12
10
8
6
4
2
0
No Preirrigation
Furrow
Sprinkler

20. Preirrigation Conclusions
Preirrigation Conclusions
• Maximum weed emergence occurred at
120 to 130 cumulative degree days (base
temperature = 10°C)
10 C)
• Preirrigation/weed removal was less
beneficial when weed density is low
• Hand weeding times are reduced if preirrigation d
i i ti and weed removal are performed
d
l
f
d
prior to crop planting.

21. Cultivation
• Best when weeds are small
• Dry conditions after cultivation
help to prevent re-rooting
• Shallow cultivation reduces the
quantity of new seeds brought
to the surface

23. Weed Seed Emergence
relative to Depth (inches)
Optimum depth
Maximum depth
Wild oat
1.0
10
7.0
70
Shepherdspurse
0.2
0.8
Lambsquarters
0.3
2.0
g
Crabgrass
0.4
1.6
Foxtail
1.0
3.0
Chickweed
Chi k
d
0.4
04
0.8
08
King 1966

24. Night Cultivation?
• Some studies have found that
cultivation at night reduces weed
germination
• GPS guided systems (?)
p
• Better results after repeat treatments
• At worst, you lose a little sleep

26. Propane Flamers
• Kills weeds like a contact
eeds
herbicide
• Treated leaves go from a glossy
g
g
y
to a mat finish
• Fuel cost??

27. Just prior
to flaming

28. 5 minutes
after flaming

29. 10 minutes
after flaming

34. Organic Herbicides
Registered for
Food Use
•
•
•
•
•
C-Cide
Green Match O
Matran EC
Weed Zap
Green Match EX
Not Registered for
Food Use
• Pine Oil
• Racer*
• Acetic Acid –
must be food grade
All are contact type herbicides – no residual activity

37. C-Cide 33% @ 70 GPA
55º F at application

38. C-Cide 33% + 1% NuFilm P
@ 70GPA
74ºF

40. C-Cide 33% + 1% NuFilm P @ 70GPA
10 DAT

41. C-Cide 25% 70gpa + 0.5% Natural Wet
81 ºF at application

42. C Cide
C-Cide 25% 70gpa + 0.5% Natural Wet
81 ºF at 1st and 76 ºF at 2nd application – treated twice

43. For Control of Annual and Broadleaf
Weeds In Non-Crop Areas
ACTIVE INGREDIENT: d-limonene …………… 70%
INERT INGREDIENTS
INGREDIENTS:……….…..………….…. 30%
Total ........................................................................100%
KEEP OUT OF REACH OF CHILDREN
CAUTION
EPA Reg. No. 82052 - 1
R N
EPA Est. No. 82052-GA-1
Manufactured by:
Cutting Edge Formulations, Inc.
5106 Bristol Industrial Way
y
Buford, GA 30518
(866) 906-WEED
DIRECTIONS FOR USE:
It is a violation of Federal Law to use this product in a manner inconsistent with its labeling.
General information: GREENMATCH O is a broad spectrum weed killer that contains a
citrus extract. It is non-selective and controls most annual weeds, both grasses and broadleaves.
For best performance, complete coverage of target weeds is necessary. Spray until thoroughly
wet. It is recommended for non-food areas such as borders, driveways, sidewalks, around mature
trees and ornamentals, around buildings, in greenhouses and around flower beds.

44. GreenMatch O 10% + 1% NuFilm P @ 70 GPA
55ºF at application

45. GreenMatch O 15% + 1% Natural wet
@ 70gpa
81º F

46. GreenMatch O 15%+ 1% Natural wet
@ 70gpa - treated twice

48. Matran EC 10% + 1% Natural Wet @ 35 GPA
55º F at application

49. Matran EC 15% + 1% Natural Wet @ 35 GPA
55º F at application

50. Matran EC 10% + 1% NuFilm P
@ 70 GPA
74º F

51. Matran EC 10% + 1% NuFilm P
@ 70 GPA
10 DAT

52. Matran 15% + 0.05% Natural wet @ 70 gpa

55. Vinegar 20% + 1% NuFilm P
@ 70 GPA
55ºF
55 F

56. Vinegar 20% + 1% NuFilm P
@ 70 GPA Treated twice

57. Vinegar 20% + 1% NuFilm P
@ 70 GPA
74ºF

58. Vinegar 20% + 1% NuFilm P
@ 70 GPA
10 DAT

59. Vinegar 20% 70gpa + 0.05% Natural Wet
0 05%
81ºF at application

60. Vinegar 20% 70gpa
+ 0.05% Natural Wet –
Treated twice

63. 0.25% v/v Natural Wet
35 gallons per acre spray volume

64. 16 Days after treatment

65. WeedZap 15% + 1% Natural Wet @ 35 GPA
55º F at application
pp

66. WeedZap 20% + 1% NuFilmP
@ 35 GPA
10 DAT

67. WeedZap 10% @ 70 GPA
p
10 DAT

68. WeedZap 10% 70gpa
+ 0.05% Natural wet
0 05%

70. GreenMatch EX 15% @ 35 GPA
10 days after application

71. GreenMatch EX 15% 70gpa +
gp
0.05% Natural wet

72. GreenMatch EX
10% 70 GPA
1% NuFilm P

73. Does age (size) make a difference?
d
2nd application d
li i date
Gr
rass control (%
%)
Youngest
g
Oldest
100
90
80
70
60
50
40
30
20
10
0
C-Cide
GreenM
GreenM EX
Matran
Vinegar
WeedZap
S. Horimoto, unpublished

74. Organic Adjuvants
Organic adjuvants

75. Matran 10% - 2 DAT

76. Matran 10% + Organic Adjuvant 1% - 2 DAT

77. Matran + WE 1098 – 1 DAT
M t

78. Matran + WE 1098
8 DAT

79. Organic Herbicides
• Good spray coverage is essential
70 GPA?
• Work better in warm (sunny?) weather (80ºF)
• Organic adjuvants improve weed control
• Treat when weeds are small
• Repeat applications are needed for larger
weeds

80. Prevention
• Avoid letting weeds go to
seed
• Do not let weeds come in on
equipment

81. Questions?