Smartweed, Swamp
(Polygonum coccineum Muhl.)

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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

A native plant which, as the name implies, can be found in wet areas such as along lakes, ponds, rivers and ditches, but can also persist in poorly drained depressional areas in cultivated fields throughout the province.

Life Cycle

Perennial, reproducing by seed and by underground horizontal roots (i.e. rhizomes).

Distinguishing Characteristics

Like all members of the smartweed family (i.e. Lady's-thumb, wild buckwheat etc.) swamp smartweed will have an ocrea at the base of each leaf stem. An ocrea is a membraneous "skin-like" piece of tissue that surrounds the stem at each node. Swamp smartweed will be distinguished from other annual smartweeds (i.e. lady's thumb) by the presence of rhizomes. Swamp smartweed can be most often confused with water smartweed, however swamp smartweed lacks a "leaf-like" flange at the top of its ocrea, which is characteristic of water smartweed.

Swamp Smartweed Pictures
Each thumbnail image links to a larger image

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Herbicide Control in Field Corn

Pre-Emergent Control

None of the products tested provided control or even supression of swamp smartweed (Table 1).

Post-Emergent Control in Corn

The post-emergent herbicides provided better control then any soil-applied herbicides, however none of the herbicides tested offered control of swamp smartweed. SUMMIT, offered the greatest level of activity at 66% control (Table 2). The "one pass" grass and broadleaf herbicide combinations such as ULTIM TOTAL, ACCENT TOTAL and OPTION 35 DF + DISTINCT offered equivalent or marginally better activity on swamp smartweed (Table 3).

Source:

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

Number of Trials:

Table 1 is based on 1 field trial conducted in Ontario.

Table 2 is based on 3 field trials conducted in Ontario.

Table 3 is based on 2 field trials conducted in Ontario.

Herbicide Rates:

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

Weed Stage:

Swamp smartweed had not emerged for pre-emergent applications and was between 4 to 60 cm in height at the time of post-emergent applications.

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

Post-Emergent Control

Post-emergent control of swamp smartweed was achieved with BLAZER in conventional soybean and glyphosate in "Roundup Ready" soybean (Table 1).

Source:

Dr. Peter Sikkema, University of Guelph.

Number of Trials:

Table 1 is based on a summary of 1 field trial in no-till soybean.

Herbicide Rates:

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

Weed Stage:

Swamp smartweed ranged from 4 to 60 cm in height at the time off all post-emergent applications.

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

Limited research would suggest that 2,4-D, BANVEL II, ESTAPROP, DICHLORPROP D or TURBOPROP offer in season control of swamp smartweed.

Source:

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

Number of Trials:

Tables 1 is based on a summary of 1 field trial in winter wheat.

Herbicide Rates:

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

Weed Stage:

Swamp smartweed was at the 2-9 leaf stage 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.