Lettuce, Prickly
(Lactuca scariola L.)

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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

Traditionally prickly lettuce would be found in waste places and older pastures. No-till crop production, particularly in soybean, has increased the presence of this weed in many areas. .

Life Cycle

Winter or summer annual reproducing only by seed. Will flower from June to late autumn.

Distinguishing Characteristics

Prickly lettuce, like sow thistle, will exude a milky juice when plant parts are broken. However prickly lettuce can be easily distinguished from any of the sow thistles by its single row of stiff, sharp prickles along the midrib on the underside of the stem leaves.

Prickly Lettuce Pictures
Each thumbnail image links to a larger image

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Herbicide Control in Field Corn

Field experiments have shown that many of the post-emergent broadleaf (Table 1) and "one-pass" grass and broadleaf co-packs (Table 2) provide adequate control of prickly lettuce.

Source:

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

Number of Trials:

Table 1 is based on a summary of 2 field trials in corn.

Table 2 is based on a summary of 1 field trial in corn.

Herbicide Rates:

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

Weed Stage:

Prickly lettuce ranged from the 3 to 20+ leaf stage (2 to 45 cm in height) 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.

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Herbicide Control in Soybeans

Pre-Plant Control

A pre-plant application of glyphosate at 2 L/ac (Table 1) should provide season long control provided the soybean crop achieves full canopy so as to inhibit any further seed germination.

Pre-Emergent Control

A residual soil applied herbicide along with a glyphosate (1 L/ac) burndown (Table 2) will also provide good control of prickly lettuce and is particularly effective for controlling secondary emergence of this weed. However, it should be noted that the activity of glyphosate is antagonized when products that contain metribuzin (i.e. Sencor, Boundary) and linuron (i.e. Lorox) are tank-mixed.

Post-Emergent Control

Aside from glyphosate, there are no post-emergent herbicides that provide adequate control of prickly lettuce (Table 3). Therefore, when growing conventional soybeans, a pre-plant glyphosate application along with a residual soil applied herbicide is critical for the control of prickly lettuce.

Source:

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

Number of Trials:

Table 1 and 2 are based on a summary of 1 field trial in soybean.

Table 3 is based on a summary of 4 field trials in soybean.

Herbicide Rates:

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

Weed Stage:

Prickly lettuce ranged from the cotyledon to 20 leaf stage (1 to 42 cm in height) 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.

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Herbicide Control in Winter Wheat

Post-Emergent Control

Field experiments have shown that many of the broadleaf herbicides registered for use in winter wheat will provide adequate control of prickly lettuce. The exception to this would be dicamba (Banvel II), which provided less than acceptable control (Table 1).

Source:

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

Number of Trials:

Table 1 is based on a summary of 2 trials in winter wheat.

Herbicide Rates:

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

Weed Stage:

Prickly lettuce ranged from the 2 to 12 leaf stage (1 to 27 cm in height) 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.