Speedwell, Corn
(Veronica arvensis 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

Corn speedwell is prominent throughout Ontario primarily in cereal and forage crops as well as lawns and roadsides..

Life Cycle

Annual or winter annual reproducing only by seed. Will germinate in late autumn or early spring and flowers in late June and then again in Autumn. One plant can produce between 50 to 100 seeds.

Distinguishing Characteristics

Corn speedwell has erect stems that spread from the base. The leaves are small, hairy on both sides with margins that have slightly rounded teeth. The most distinguishable characteristic of corn speedwell is its blue-violet flowers (with 4 pedals) and the rounded, heart shaped seedpods. For more information, refer to Page 195 in OMAF Publication 505 - Ontario Weeds.

Corn Speedwell Pictures
Each thumbnail image links to a larger image

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Herbicide Control in Field Corn

Very limited work has been done on corn speedwell control in Ontario. This species was recently evaluated in a 2004 field trial, but not as the target species and in a non-crop situation, therefore only a handful of corn herbicides were evaluated. Results from this single trial would indicate that glyphosate (for Roundup Ready corn only), linuron (LOROX) and primisulfuron/dicamba (SUMMIT) provide effective control of corn speedwell (Table 1).

Scientific literature on the control of corn speedwell in corn is limited. Atrazine is cited as providing excellent control of corn speedwell (Saric et al., 1975).

 

Table 1. Corn speedwell control in corn with selected herbicides.

Active Ingredient	Trade Name (application timing)	% Control
glyphosate	glyphosate (2 L/ac - Roundup Ready corn only)	99
linuron	LOROX L (PRE)	97
primisulfuron/dicamba	SUMMIT (POST)	97
foramsulfuron	OPTION 35DF (POST)	0
nicosulfuron/rimsulfuron	ULTIM (POST)	0

Source:

Dr. François Tardif, University of Guelph.

Number of Trials:

Table 1 is based on a summary of 1 field trial with no grown crop.

Herbicide Rates:

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

Weed Stage:

Stage of the species was unkown since it wasn't the target species at application.

References

Saric, T., Numic, R. and N. Hadzihajdic. 1975. The results of 5-year experiments with herbicides in maize. Fragmenta Herbologica Jugoslavica. No.55, pp.14.

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

Very limited work has been done on corn speedweel control in Ontario. This species was recently evaluated in a 2004 field trial, but not as the target species and in a non-crop situation, therefore only a handful of soybean herbicides were evaluated. Results from this single trial would indicate that glyphosate (for Roundup Ready soybean only), linuron (LOROX) and metribuzin (SENCOR) provide effective control of corn speedwell (Table 1).

A scientific literature search on the control of corn speedwell in soybean came up with no information.

Table 1. Corn speedwell control in soybean with selected herbicides.

Active Ingredient	Trade Name (application timing)	% Control
glyphosate	glyphosate (2 L/ac - Roundup Ready corn only)	99
glyphosate + chlorimuron-ethyl	glyphosate (1 L/ac) + CLASSIC - Roundup Ready soybean only)	99
linuron	LOROX L (PRE - High Rate)	97
metribuzin	SENCOR (PRE - High Rate)	92
thifensulfuron-methyl	PINNACLE (POST)	54
chlorimuron-ethyl	CLASSIC (POST)	50

Source:

Dr. François Tardif, University of Guelph.

Number of Trials:

Table 1 is based on a summary of 1 field trial planted to no-till soybeans.

Herbicide Rates:

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

Weed Stage:

Stage of the species was unkown since it wasn't the target species at 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

In the mid-1990's, Mike Cowbrough scouted barley and wheat fields over a four month period in the United Kingdom. At that time "speedwells" were a considerable problem in many of the cereal crops. Grower's that he spoke with believed that they were getting better control in previous years when they had been using three way herbicide mixes that contained MCPA, mecoprop and dicamba (i.e. Sword, Target), instead of the popular bromoxynil/MCPA (i.e. Buctril M) combination.
In Ontario, Peter Sikkema (Ridgetown College) conducted a field experiment in 2003 that evaluated the control of Corn speedwell in winter wheat (see Table 1). His results are consistent with the experience of U.K. cereal producers in that herbicides that contained mecoprop, dichlorprop or high rates of MCPA generally provided acceptable control of Corn speedwell.

 

Table 1. Corn speedwell control in winter wheat with various post-emergent herbicides.

Active Ingredient	Trade Name (application timing)	% Control
MCPA Ester	Numerous Products Exist	99
thifensulfuron-methyl/tribenuron-methyl	REFINE EXTRA	95
dichlorprop/2,4-D	ESTAPROP, DICHLROPROP-D or TURBOPROP	93
MCPA Amine	Numerous Products Exist	90
dicamba/MCPA/mecoprop	SWORD or TARGET	90
2,4-D Ester	Numerous Products Exist	88
dicamba/MCPA	DYVEL	84
2,4-D Amine	Numerous Products Exist	63
dicamba	BANVEL II	55
bromoxynil/MCPA	BUCTIL M, BADGE or MEXTROL	50

UPDATE: In 2004, Dr. François Tardif and Mike Cowbrough observed 91% control of corn speedwell plots sprayed with REFINE EXTRA.

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:

Corn speedwell was at 5-10 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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