Dandelion (Taraxacum officinale Weber.)

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Table of Contents

  1. History
  2. Life Cycle
  3. Distinguishing Characteristics
  4. Control in Corn
  5. Control in Soybeans
  6. Control in Winter Wheat

History

One of the most widespread and abundant weeds in Ontario growing in virtually every type of habitat.

Life Cycle

Perennial, reproducing only by seed.

Distinguishing Characteristics

Probably the most easily identified weed, dandelion contains a milky white juice, a deep taproot, irregularly lobed leaves and a yellow flower head. For more information refer to Page 252 in OMAF Publication 505 - Ontario Weeds.

Dandelion Pictures
Each thumbnail image links to a larger image

Link to larger photo of Dandelion plant with yellow flower
Link to larger photo of Dandelion seeds
Link to larger photo of Dandelion leaves

Herbicide Control in Field Corn

Pre-Plant Control:

Pre-plant applications are effective at controlling established dandelions and newly emerged seedlings. A number of herbicides and tank-mixes will provide adequate control (Table 1). Certain products and tank-mixes stipulate cropping restrictions (Table 2).

Table 1. Visual control of dandelion in the spring, following pre-plant (PP) applications of various herbicides
Active Ingredient Trade Name (product rate/acre)
% Control
glyphosate glyphosate (2 L/ac)
94
glyphosate + 2,4-D Ester glyphosate (1 L/ac) + 2,4-D Ester (0.5 L/ac)
93
glyphosate glyphosate (1.5 L/ac)
91
2,4-D Ester 2,4-D Ester (1 L/ac)
89
glyphosate + amitrol glyphoate (1 L/ac) + AMITROLE 240 (1 L/ac)
88
glyphosate + dicamba glyphosate (1 L/ac) + BANVEL II (0.25 L/ac)
85
dicamba BANVEL II (0.5 L/ac)
51

Table 2. A summary of cropping restrictions that exist with fall or spring applications*
Trade Name Restrictions
AMITROL 240 If planting corn and whitebeans wait 10-14 days after application before planting. If planting soybeans wait 6 days after applications before planting.
BANVEL II If applied alone or with glyphosate before September 1st, then field corn, soybean, spring cereals and canola can be planted in the spring. If applied after September 1st or in the spring, then only field corn can be planted after application.
2,4-D Ester Use only the low rate (0.5 L/ac) in the spring. Only field corn or spring cereals can be planted after a spring application, however a 14 day interval between application and planting is required. No specific crop restrictions are mentioned when applied alone or with glyphosate in the fall. However, to be safe, 2,4-D should be treated the same as BANVEL II.

* A guideline only. The user must consult the manufacturer's product label before using any of the products mentioned in the section.

Pre or Post Emergent Control

A pre-plant or fall applied application is ideal for dandelion control in corn. If either one of those applications couldn't be made then based on limited research, a post-emergent application of Banvel II should provide good control of dandelion (Table 3).

Field experience has suggested that pre-emerge applications of isoxaflutole/atrazine (CONVERGE) or post-emergent applications of nicosulfuron/rimsulfuron + diflufenzopyr/dicamba (ULTIM TOTAL) can be effective at controlling dandelion.

Table 3. Control of dandelion in field corn using various post-emergent herbicides
Active Ingredient Trade Name (application timing)
% Control
dicamba BANVEL II (post - high rate)
89
dicamba/atrazine MARKSMAN (post)
74
diflufenzopyr/dicamba DISTINCT (post)
70
2,4-D/atrazine SHOTGUN (post)
40
atrazine numerous products exists (post)
25
bromoxynil + atrazine PARDNER or KORIL + atrazine (post)
23
primisulfuron/dicamba SUMMIT (post)
20
mesotrione CALLISTO (post)
13
prosulfuron/dicamba PEAKPLUS (post)
10
Post Harvest Control

Fall herbicide applications are ideal for controlling larger established dandelions. Cooler temperatures will trigger dandelion to move sugars down to the taproot for storage. Applying a systemic herbicide in the fall promotes movement of the active ingredient down to the roots providing effective long-term control. In general numerous products and tank-mixes provide adequate control of dandelion when applied in the fall (Table 4). Deciding on which one to use will depend on the weed spectrum, cost and rotational flexibility of the specific herbicide or tank-mix. Refer to Table 2 and the product label for information on rotational restrictions.

Table 4. Visual control of dandelion in the spring, following fall applications of various herbicides
Active Ingredient Trade Name (rate/acre)
% Control
amitrole AMITROL 240 (3L/ac)
96
glyphosate + dicamba glyphosate (1 L/ac) + BANVEL II (0.25 L/ac)
92
glyphosate glyphosate (1.5 L/ac)
91
dicamba BANVEL II (0.5 L/ac)
89
2,4-D 2,4-D Ester (1 L/ac)
89
glyphosate + 2,4-D glyphosate (1 L/ac) + 2,4-D Ester (0.5 L/ac)
89
amitrole AMITROL 240 (2 L/ac)
88
glyphosate + amitrole glyphosate (1 L/ac) + AMITROL 240 (1 L/ac)
86

Source:
Dr. Peter Sikkema, Ridgetown College, University of Guelph.

Number of Trials:

Tables 1 and 4 are based on a summary of 2 field trials.
Table 3 based on a summary of 1 field trial.

Herbicide Rates:
Rates used in this trial are listed in OMAF Publication 75 - Guide to Weed Control.

Weed Stage:
Dandelion size ranged from 5 to 40 cm om diameter at the time of application.

What has been your experience?
We want your feedback. Let us know what you have experienced with these or other products, as well as any other effective management strategies.


Herbicide Control in Soybeans

Pre-Plant Control:

Pre-plant applications are effective at controlling established dandelions and newly emerged seedlings. A number of herbicides and tank-mixes will provide adequate control (Table 1). Certain products and tank-mixes stipulate cropping restrictions (Table 2). BANVEL II or 2,4-D products CANNOT be applied in the spring prior to planting soybean as unacceptable crop injury can occur.

Table 1. Visual control of dandelion in the spring, following pre-plant (PP) applications of various herbicides
Active Ingredient Trade Name (product rate/acre)
% Control
glyphosate glyphosate (2 L/ac)
94
glyphosate + 2,4-D Ester glyphosate (1 L/ac) + 2,4-D Ester (0.5 L/ac)
93
glyphosate glyphosate (1.5 L/ac)
91
2,4-D Ester 2,4-D Ester (1 L/ac)
89
glyphosate + amitrol glyphoate (1 L/ac) + AMITROLE 240 (1 L/ac)
88
glyphosate + dicamba glyphosate (1 L/ac) + BANVEL II (0.25 L/ac)
85
dicamba BANVEL II (0.5 L/ac)
51

Table 2. A summary of cropping restrictions that exist with fall or spring applications*
Trade Name Restrictions
AMITROL 240 If planting corn and whitebeans wait 10-14 days after application before planting. If planting soybeans wait 6 days after applications before planting.
BANVEL II If applied alone or with glyphosate before September 1st, then field corn, soybean, spring cereals and canola can be planted in the spring. If applied after September 1st or in the spring, then only field corn can be planted after application.
2,4-D Ester Use only the low rate (0.5 L/ac) in the spring. Only field corn or spring cereals can be planted after a spring application, however a 14 day interval between application and planting is required. No specific crop restrictions are mentioned when applied alone or with glyphosate in the fall. However, to be safe, 2,4-D should be treated the same as BANVEL II.

* A guideline only. The user must consult the manufacturer's product label before using any of the products mentioned in the section.

Post Emergent Control

Field observations have shown that chlorimuron-ethyl (CLASSIC) will provide good post-emergent and residual control of dandelion seedlings provided they are less than 15 cm. in diameter.

Post Harvest Control

Fall herbicide applications are ideal for controlling larger established dandelions. Cooler temperatures will trigger dandelion to move sugars down to the taproot for storage. Applying a systemic herbicide in the fall promotes movement of the active ingredient down to the roots providing effective long-term control. In general numerous products and tank-mixes provide adequate control of dandelion when applied in the fall (Table 4). Deciding on which one to use will depend on the weed spectrum, cost and rotational flexibility of the specific herbicide or tank-mix. Refer to Table 2 and the product label for information on rotational restrictions.

Table 4. Visual control of dandelion in the spring, following fall applications of various herbicides
Active Ingredient Trade Name (rate/acre)
% Control
amitrole AMITROL 240 (3L/ac)
96
glyphosate + dicamba glyphosate (1 L/ac) + BANVEL II (0.25 L/ac)
92
glyphosate glyphosate (1.5 L/ac)
91
dicamba BANVEL II (0.5 L/ac)
89
2,4-D 2,4-D Ester (1 L/ac)
89
glyphosate + 2,4-D glyphosate (1 L/ac) + 2,4-D Ester (0.5 L/ac)
89
amitrole AMITROL 240 (2 L/ac)
88
glyphosate + amitrole glyphosate (1 L/ac) + AMITROL 240 (1 L/ac)
86

Source:
Dr. Peter Sikkema, Ridgetown College, University of Guelph.

Number of Trials:

Tables 1 and 3are based on a summary of 2 field trials.

Herbicide Rates:
Rates used in this trial are listed in OMAF Publication 75 - Guide to Weed Control.

Weed Stage:
Dandelion size ranged from 5 to 40 cm om diameter at the time of application.

What has been your experience?
We want your feedback. Let us know what you have experienced with these or other products, as well as any other effective management strategies.


Herbicide Control in Winter Wheat

Post Emergent Control

Estaprop, Turboprop or Dichlorprop-D are the only products that provide adequate control of dandelion. Winter wheat fields should be scouted for the presence of dandelions in mid to late April and if present in high enough populations should be treated as early as possible. Late applications of Estaprop, turboprop or Dichlorprop-D can cause unacceptable levels of crop injury and therefore should be applied before the late tillering or 1st node stage of winter wheat.

Table 1. Visual control of dandelion in winter wheat using various post-emergent herbicides
Active Ingredient Trade Name
% Control
dichlorprop/2,4-D ESTAPROP, TURBOPROP, or DICHLORPROP D
91
bromoxynil/MCPA BUCTRIL M, BADGE or MEXTROL
64
2,4-D 2,4-D Amine (Numerous Brands Exist)
61
MCPA MCPA AMINE (Numerous Brands Exist)
61
dicamba/MCPA/mecoprop SWORD or TARGET
61
thifensulfuron-methyl/tribenuron methyl REFINE EXTRA
56

Source:

Dr. Peter Sikkema, Ridgetown College, University of Guelph.

Number of Trials:

Tables 1 is based on a summary of 3 field trials.

Herbicide Rates:
Rates used in this trial are listed in OMAF Publication 75 - Guide to Weed Control.

Weed Stage:
Dandelion size ranged from 5 to 40 cm om diameter at the time of application.

What has been your experience?
We want your feedback. Let us know what you have experienced with these or other products, as well as any other effective management strategies.


For more information:
Toll Free: 1-877-424-1300
Local: (519) 826-4047
Email: ag.info@omaf.gov.on.ca