North Dakota State University
NDSU Extension Service

Survey of Weeds in North Dakota - 2000

ER-83, May 2003
R. K. Zollinger, NDSU Extension Weed Specialist

Table 10. The 20 most abundant weeds in North Dakota based on weed index.

Spring 2000		Summer 2000		Average of 1978 and 1979
Weed species	Weed Index	Weed species	Weed Index	Weed species	Weed Index
Green foxtail	103.0	Green foxtail	73.8	Green foxtail	236.0
Wild mustard	50.0	Wild oat	38.8	Wild oat	61.8
Wild buckwheat	46.2	Yellow foxtail	37.5	Wild buckwheat	53.3
Wild oat	35.4	Kochia	33.1	Redroot pigweed	42.4
Canada thistle	30.4	Wild buckwheat	28.6	Yellow foxtail	28.5
Kochia	30.2	Canada thistle	26.5	Common lambsquaters	24.7
Yellow foxtail	28.0	Pigweed species	19.6	Wild mustard	22.8
Pigweed species	26.8	Volunteer cereal	10.6	Russian thistle	19.3
Common lambsquarters	23.3	Common ragweed	10.4	Kochia	16.9
Volunteer cereal	14.8	Field bindweed	8.7	Field bindweed	11.5
Sunflower	13.8	Common lambsquarters	8.6	Canada thistle	10.7
Russian thistle	13.5	Quackgrass	8.6	Volunteer sunflower	8.0
Quackgrass	13.0	Russian thistle	7.7	Perennial sowthistle	7.5
Field pennycress	9.9	Wild mustard	7.1	Prostrate pigweed	5.8
Field bindweed	9.7	Eastern black nightshade	5.6	Nightflowering catchfly	5.4
Common ragweed	9.1	Perennial sowthistle	5.3	Quackgrass	3.9
Canola	6.6	Common milkweed	5.1	Prairie wild rose	3.6
Eastern black nightshade	6.2	Sunflower	4.5	Field pennycress	3.0
Common cocklebur	6.0	Common cocklebur	4.4	Ragweed	2.5
Soybean	5.0	Field pennycress	4.3	Common cocklebur	2.2

Table 11. The 20 most abundant weeds in HRS wheat, durum wheat, barley, tame oats.

Spring 2000		Summer 2000		Average of 1978 and 1979
HRS wheat, durum wheat, barley, tame oat		HRS wheat, durum wheat, barley		Spring wheat, barley, oat
Weed species	Weed Index	Weed species	Weed Index	Weed species	Weed Index
Green foxtail	114.0	Green foxtail	82.3	Green foxtail	250.2
Wild buckwheat	54.2	Wild oat	52.6	Wild oat	64.5
Wild mustard	48.8	Yellow foxtail	43.2	Common lambsquarters	62.1
Wild oat	36.4	Wild buckwheat	35.3	Wild buckwheat	57.8
Kochia	35.8	Kochia	35.3	Redroot pigweed	41.4
Pigweed species	29.8	Canada thistle	25.6	Yellow foxtail	27.7
Canada thistle	26.3	Pigweed species	18.7	Russian thistle	22.6
Yellow foxtail	23.1	Field bindweed	9.9	Wild mustard	20.5
Common lambsquarters	22.8	Quackgrass	9.0	Kochia	18.7
Sunflower	17.9	Common lambsquarters	7.9	Field bindweed	13.4
Russian thistle	16.9	Common ragweed	7.6	Canada thistle	11.4
Field bindweed	11.9	Russian thistle	6.8	Volunteer sunflower	9.4
Field pennycress	11.4	Common milkweed	6.7	Perennial sowthistle	9.2
Quackgrass	10.4	Perennial sowthistle	4.8	Nightflowering catchfly	6.2
Common ragweed	8.9	Sunflower	4.1	Prostrate pigweed	5.5
Canola	8.5	Wild mustard	4.0	Quackgrass	4.8
Soybean	6.1	Field pennycress	3.8	Prairie wild rose	3.9
Eastern black nightshade	5.4	Barnyardgrass	3.2	Common cocklebur	2.5
Perennial sowthistle	5.2	Common cocklebur	3.0	Common purslane	2.1
Volunteer cereal	4.2	Common mallow	2.6	Ragweed	1.8

Table 12. The 20 most abundant weeds in flax.

Spring 2000		Average of 1978 and 1979
Weed species	Weed Index	Weed species	Weed Index
Green foxtail	129.4	Green foxtail	201.1
Wild mustard	69.6	Wild buckwheat	64.1
Wild buckwheat	68.1	Wild mustard	52.8
Volunteer cereal	52.7	Wild oat	44.2
Wild oat	52.1	Redroot pigweed	43.1
Kochia	39.7	Common lambsquarters	36.0
Yellow foxtail	35.2	Yellow foxtail	30.4
Field pennycress	27.4	Russian thistle	23.8
Canada thistle	26.3	Kochia	21.5
Quackgrass	21.4	Canada thistle	12.7
Pigweed species	20.4	Field bindweed	12.4
Common lambsquarters	17.7	Barnyardgrass	10.4
Field bindweed	17.4	Volunteer sunflower	9.7
Canola	12.3	Prostrate spurge	8.2
Russian thistle	11.5	Perennial sowthistle	7.9
Shepherd's-purse	9.9	Prostrate pigweed	7.7
Flixweed/Tansy mustard	8.8	Field pennycress	6.7
Downy brome	7.9	Quackgrass	6.6
Sunflower	6.3	Common cocklebur	5.6
Perennial sowthistle	5.7	Musk thistle	3.9

Table 13. The 20 most abundant weeds in sunflower.

Spring 2000		Summer 2000		1979
Weed species	Weed Index	Weed species	Weed Index	Weed species	Weed Index
Green foxtail	100.8	Green foxtail	92.0	Green foxtail	149.6
Wild mustard	67.6	Yellow foxtail	39.1	Wild mustard	57.0
Canada thistle	43.7	Kochia	31.5	Yellow foxtail	46.1
Volunteer cereal	41.8	Canada thistle	31.5	Redroot pigweed	32.9
Wild buckwheat	34.1	Wild buckwheat	29.3	Wild buckwheat	30.5
Wild oat	32.6	Volunteer cereal	29.2	Wild oat	28.0
Yellow foxtail	27.1	Pigweed species	25.9	Common lambsquarters	27.1
Pigweed species	25.2	Wild oat	21.8	Canada thistle	15.4
Kochia	21.5	Common ragweed	18.4	Russian thistle	12.8
Quackgrass	17.3	Russian thistle	15.4	Kochia	11.8
Prickly lettuce	10.5	Eastern black nightshade	13.1	Field bindweed	9.3
Russian thistle	10.0	Field bindweed	11.6	Prostrate spurge	8.6
Common ragweed	9.8	Canola	11.3	Quackgrass	7.9
Field pennycress	9.4	Prickly lettuce	10.8	Prostrate pigweed	7.3
Common milkweed	8.6	Wild mustard	10.5	Ragweed	6.8
Common cocklebur	8.5	Flixweed/Tansy mustard	10.0	Field pennycress	6.6
Canola	7.9	Common lambsquarters	9.6	Perennial sowthistle	5.7
Common lambsquarters	6.1	Quackgrass	9.3	Prairie wild rose	4.8
Common mallow	5.9	Perennial sowthistle	7.6	Common purslane	4.6
Field bindweed	4.9	Field pennycress	6.6	Shepherd's-purse	3.8

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EB-83, May 2003

NDSU Extension Service, North Dakota State University of Agriculture and Applied Science, and U.S. Department of Agriculture cooperating. Sharon D. Anderson, Director, Fargo, North Dakota. Distributed in furtherance of the Acts of Congress of May 8 and June 30, 1914. We offer our programs and facilities to all persons regardless of race, color, national origin, religion, sex, disability, age, Vietnam era veterans status, or sexual orientation; and are an equal opportunity employer. This publication will be made available in alternative format upon request to people with disabilities (701) 231-7881. North Dakota State University NDSU Extension Service