North Dakota State University
NDSU Extension Service
ER-83, May 2003
R. K. Zollinger, NDSU Extension Weed Specialist
| Table 67. North Dakota weed infestations in previous crop of HRS wheat, durum wheat, barley, and tame oat based on 731 surveyed fields, spring 2000. | ||||||||
| Weed | ||||||||
| Weed | Field Uniformity | Weed Density | Density Range | Weed | ||||
| Weed species | Frequency | All | Infested | All | Infested | Low | High | Index |
| (%) | (%) | (%) | - - Plants/m2 - - | - - Plants/m2 - - | ||||
| Green foxtail | 68.1 | 24.7 | 36.3 | 26.1 | 38.3 | 2.3 | 29.0 | 108.4 |
| Wild mustard | 49.5 | 17.6 | 35.5 | 6.6 | 13.4 | 0.1 | 5.3 | 49.6 |
| Wild buckwheat | 45.0 | 15.6 | 34.7 | 6.1 | 13.5 | 0.1 | 5.2 | 44.8 |
| Wild oat | 34.3 | 12.6 | 36.7 | 6.8 | 19.9 | 0.1 | 7.9 | 40.0 |
| Canada thistle | 36.5 | 9.4 | 25.7 | 3.1 | 8.4 | <0.1 | 3.7 | 28.7 |
| Kochia | 28.2 | 9.1 | 32.3 | 4.1 | 14.6 | 0.1 | 9.4 | 28.1 |
| Volunteer cereal | 26.5 | 10.1 | 38.2 | 3.4 | 12.6 | <0.1 | 5.0 | 26.8 |
| Pigweed species | 24.1 | 8.4 | 34.9 | 3.7 | 15.2 | <0.1 | 6.3 | 25.0 |
| Yellow foxtail | 16.8 | 6.8 | 40.2 | 5.2 | 31.2 | 0.3 | 15.3 | 24.6 |
| Common lambsquarters | 21.2 | 5.6 | 26.2 | 1.8 | 8.5 | <0.1 | 3.8 | 16.8 |
| Quackgrass | 18.3 | 4.2 | 22.9 | 2.0 | 11.1 | <0.1 | 6.1 | 15.0 |
| Russian thistle | 15.9 | 4.4 | 28.0 | 1.8 | 11.5 | <0.1 | 4.8 | 14.0 |
| Field bindweed | 14.1 | 3.6 | 25.5 | 1.2 | 8.5 | <0.1 | 4.0 | 11.1 |
| Field pennycress | 13.3 | 3.6 | 27.2 | 1.3 | 9.8 | <0.1 | 5.7 | 11.1 |
| Common ragweed | 9.6 | 2.1 | 21.4 | 0.8 | 7.9 | <0.1 | 5.7 | 7.0 |
| Common milkweed | 6.7 | 1.2 | 17.8 | 0.3 | 4.7 | <0.1 | 2.7 | 4.2 |
| Common cocklebur | 5.1 | 1.5 | 29.5 | 0.4 | 7.9 | <0.1 | 2.9 | 4.1 |
| Eastern black nightshade | 5.7 | 1.3 | 23.1 | 0.3 | 5.5 | <0.1 | 2.9 | 4.0 |
| Prickly lettuce | 5.6 | 1.4 | 24.1 | 0.3 | 4.5 | <0.1 | 2.3 | 3.8 |
| Sunflower | 5.9 | 1.2 | 21.2 | 0.2 | 4.2 | <0.1 | 2.3 | 3.8 |
| Perennial sowthistle | 5.6 | 1.0 | 18.3 | 0.4 | 6.7 | <0.1 | 3.8 | 3.8 |
| Flixweed/Tansy mustard | 5.7 | 1.3 | 22.6 | 0.2 | 4.0 | <0.1 | 2.1 | 3.7 |
| Annual smartweed | 4.7 | 1.0 | 21.5 | 0.3 | 7.1 | <0.1 | 5.1 | 3.3 |
| Common mallow | 3.8 | 0.9 | 24.3 | 0.3 | 8.1 | <0.1 | 4.9 | 2.9 |
| Dandelion | 4.1 | 0.9 | 22.0 | 0.1 | 3.2 | <0.1 | 1.6 | 2.6 |
| Common purslane | 2.9 | 0.8 | 27.1 | 0.2 | 7.2 | <0.1 | 2.4 | 2.2 |
| Barnyardgrass | 2.1 | 0.7 | 32.7 | 0.2 | 11.9 | <0.1 | 4.2 | 1.9 |
| Shepherd's-purse | 2.1 | 0.5 | 23.3 | 0.2 | 10.8 | <0.1 | 4.4 | 1.7 |
| Fairy candelabra | 1.9 | 0.6 | 29.3 | 0.2 | 8.5 | <0.1 | 3.3 | 1.6 |
| Downy brome | 1.5 | 0.4 | 25.5 | 0.2 | 13.1 | <0.1 | 6.5 | 1.3 |
| Prairie wild rose | 1.9 | 0.3 | 15.7 | 0.1 | 2.8 | <0.1 | 1.9 | 1.1 |
| Canola | 1.1 | 0.4 | 32.5 | 0.1 | 9.4 | <0.1 | 5.5 | 1.0 |
| Sweetclover | 1.0 | 0.3 | 30.0 | 0.1 | 12.9 | <0.1 | 5.9 | 0.9 |
| Giant ragweed | 1.0 | 0.2 | 24.3 | 0.1 | 6.3 | <0.1 | 2.7 | 0.7 |
| Lanceleaf sage | 1.0 | 0.2 | 25.7 | 0.1 | 5.5 | <0.1 | 2.7 | 0.7 |
| Horseweed | 1.2 | 0.2 | 16.7 | <0.1 | 2.2 | <0.1 | 1.3 | 0.7 |
| Hedge bindweed | 0.7 | 0.2 | 36.0 | <0.1 | 6.9 | <0.1 | 2.2 | 0.6 |
| Prostrate pigweed | 0.7 | 0.2 | 30.0 | 0.1 | 8.2 | <0.1 | 3.4 | 0.6 |
| Wild-proso millet | 0.8 | 0.2 | 25.0 | <0.1 | 3.9 | <0.1 | 1.7 | 0.6 |
| Curly dock | 1.0 | 0.2 | 17.1 | <0.1 | 2.9 | <0.1 | 1.9 | 0.5 |
| Cutleaf nightshade | 0.8 | 0.2 | 21.7 | <0.1 | 5.0 | <0.1 | 3.3 | 0.5 |
| Greenflower pepperweed | 1.1 | 0.1 | 12.5 | <0.1 | 1.5 | <0.1 | 1.1 | 0.5 |
| Whitlowwart species | 0.8 | 0.2 | 21.7 | <0.1 | 2.9 | <0.1 | 1.5 | 0.5 |
| Common chickweed | 0.7 | 0.1 | 14.0 | <0.1 | 6.7 | <0.1 | 5.8 | 0.4 |
| Foxtail barley | 0.8 | 0.1 | 10.0 | <0.1 | 2.0 | <0.1 | 1.8 | 0.4 |
| Alfalfa | 0.5 | 0.1 | 20.0 | <0.1 | 4.3 | <0.1 | 2.3 | 0.3 |
| Buffalobur | 0.5 | 0.1 | 20.0 | <0.1 | 3.2 | <0.1 | 1.8 | 0.3 |
| Biennial wormwood | 0.5 | 0.1 | 20.0 | <0.1 | 2.4 | <0.1 | 1.3 | 0.3 |
| Hairy nightshade | 0.4 | <0.1 | 3.3 | 0.1 | 17.6 | <0.1 | 13.7 | 0.3 |
| Yellow woodsorrel | 0.4 | 0.1 | 26.7 | <0.1 | 5.0 | <0.1 | 2.3 | 0.3 |
| Erect knotweed | 0.4 | 0.1 | 16.7 | <0.1 | 5.7 | <0.1 | 2.7 | 0.3 |
| Venice mallow | 0.3 | 0.1 | 25.0 | <0.1 | 15.6 | <0.1 | 15.0 | 0.3 |
| Marshelder | 0.5 | 0.1 | 10.0 | <0.1 | 1.6 | <0.1 | 1.5 | 0.3 |
| Tall waterhemp | 0.4 | 0.1 | 20.0 | <0.1 | 3.9 | <0.1 | 2.0 | 0.3 |
| Horsetail | 0.4 | 0.1 | 13.3 | <0.1 | 3.9 | <0.1 | 3.3 | 0.2 |
| Nightflowering catchfly | 0.4 | 0.1 | 13.3 | <0.1 | 1.8 | <0.1 | 1.3 | 0.2 |
| Swamp smartweed | 0.4 | <0.1 | 10.0 | <0.1 | 1.1 | <0.1 | 1.0 | 0.2 |
| Soybean | 0.3 | 0.1 | 25.0 | <0.1 | 2.7 | <0.1 | 1.0 | 0.2 |
| Leafy spurge | 0.3 | <0.1 | 15.0 | <0.1 | 4.3 | <0.1 | 3.5 | 0.2 |
| False chamomile | 0.3 | 0.1 | 20.0 | <0.1 | 2.2 | <0.1 | 1.0 | 0.2 |
| Purslane speedwell | 0.3 | <0.1 | 15.0 | <0.1 | 3.2 | <0.1 | 2.0 | 0.2 |
| Safflower | 0.1 | 0.1 | 40.0 | <0.1 | 5.4 | <0.1 | 2.0 | 0.1 |
| Wild vetch | 0.1 | <0.1 | 10.0 | <0.1 | 1.1 | <0.1 | 1.0 | 0.1 |
| Flax | 0.1 | <0.1 | 10.0 | <0.1 | 1.1 | <0.1 | 1.0 | 0.1 |
| Weed free | 38.0 | 12.5 | 32.9 | - | - | - | - | - |
| Table 68. North Dakota weed infestations in previous crop of canola and tame mustard based on 135 surveyed fields, spring 2000. | ||||||||
| Weed | ||||||||
| Weed | Field Uniformity | Weed Density | Density Range | Weed | ||||
| Weed species | Frequency | All | Infested | All | Infested | Low | High | Index |
| (%) | (%) | (%) | - - Plants/m2 - - | - - Plants/m2 - - | ||||
| Green foxtail | 68.1 | 22.2 | 32.6 | 23.8 | 35.0 | 2.3 | 33.0 | 100.6 |
| Canola | 42.2 | 16.5 | 39.1 | 13.1 | 31.1 | 0.4 | 17.3 | 61.2 |
| Kochia | 39.3 | 15.3 | 38.9 | 6.9 | 17.5 | <0.1 | 8.1 | 44.3 |
| Wild mustard | 41.5 | 15.8 | 38.0 | 6.1 | 14.6 | <0.1 | 6.0 | 43.7 |
| Wild oat | 38.5 | 11.3 | 29.4 | 6.4 | 16.7 | 0.1 | 6.7 | 39.2 |
| Wild buckwheat | 39.3 | 13.8 | 35.1 | 5.2 | 13.2 | 0.1 | 4.7 | 39.0 |
| Canada thistle | 43.7 | 10.7 | 24.6 | 3.5 | 7.9 | <0.1 | 3.8 | 33.4 |
| Pigweed species | 28.1 | 7.7 | 27.4 | 3.6 | 12.8 | 0.1 | 9.1 | 25.5 |
| Russian thistle | 22.2 | 6.9 | 31.0 | 3.5 | 15.9 | 0.1 | 7.6 | 22.5 |
| Yellow foxtail | 14.1 | 5.1 | 36.3 | 4.3 | 30.7 | 0.5 | 15.4 | 19.9 |
| Quackgrass | 23.0 | 4.9 | 21.3 | 2.8 | 12.0 | <0.1 | 6.5 | 19.0 |
| Field pennycress | 14.1 | 4.9 | 34.7 | 2.5 | 17.8 | <0.1 | 9.3 | 15.4 |
| Common lambsquarters | 18.5 | 4.4 | 23.6 | 1.6 | 8.6 | <0.1 | 5.2 | 14.3 |
| Field bindweed | 14.1 | 3.4 | 24.2 | 1.0 | 7.4 | <0.1 | 2.5 | 10.5 |
| Common mallow | 13.3 | 3.0 | 22.8 | 1.0 | 7.8 | <0.1 | 4.8 | 9.9 |
| Perennial sowthistle | 11.1 | 2.4 | 22.0 | 0.7 | 6.0 | <0.1 | 3.1 | 7.7 |
| Common ragweed | 10.4 | 2.1 | 20.7 | 0.8 | 7.6 | <0.1 | 5.8 | 7.4 |
| Prickly lettuce | 8.9 | 2.6 | 29.2 | 0.6 | 7.3 | <0.1 | 3.3 | 7.1 |
| Annual smartweed | 5.2 | 1.0 | 18.6 | 1.1 | 22.0 | 0.4 | 32.7 | 5.4 |
| Flixweed/Tansy mustard | 6.7 | 1.7 | 25.6 | 0.3 | 4.8 | <0.1 | 2.1 | 4.7 |
| Shepherd's-purse | 4.4 | 1.3 | 28.3 | 0.5 | 12.0 | <0.1 | 6.3 | 4.0 |
| Volunteer cereal | 3.7 | 1.2 | 32.0 | 0.5 | 14.0 | <0.1 | 9.6 | 3.6 |
| Sunflower | 3.7 | 0.9 | 24.0 | 0.5 | 14.0 | <0.1 | 4.0 | 3.3 |
| Common cocklebur | 4.4 | 0.7 | 15.0 | 0.1 | 2.9 | <0.1 | 2.0 | 2.4 |
| Dandelion | 3.7 | 0.9 | 24.0 | 0.1 | 3.7 | <0.1 | 1.6 | 2.4 |
| Barnyardgrass | 3.0 | 0.7 | 22.5 | 0.2 | 6.7 | <0.1 | 3.8 | 2.1 |
| Eastern black nightshade | 3.0 | 0.7 | 22.5 | 0.1 | 4.0 | <0.1 | 1.8 | 1.9 |
| Fairy candelabra | 2.2 | 0.6 | 26.7 | 0.2 | 11.1 | <0.1 | 5.3 | 1.9 |
| Common milkweed | 3.0 | 0.3 | 10.0 | 0.1 | 3.5 | <0.1 | 3.3 | 1.5 |
| Nightflowering catchfly | 0.7 | 0.6 | 80.0 | 0.3 | 36.6 | <0.1 | 7.0 | 1.5 |
| Prostrate pigweed | 2.2 | 0.4 | 16.7 | 0.1 | 4.7 | <0.1 | 3.7 | 1.4 |
| Giant ragweed | 1.5 | 0.4 | 30.0 | 0.1 | 8.1 | <0.1 | 3.5 | 1.2 |
| Curly dock | 1.5 | 0.2 | 15.0 | 0.1 | 9.1 | <0.1 | 8.0 | 1.0 |
| Common purslane | 0.7 | 0.4 | 50.0 | 0.2 | 22.6 | <0.1 | 6.0 | 1.0 |
| Hedge bindweed | 1.5 | 0.4 | 25.0 | 0.1 | 3.8 | <0.1 | 1.5 | 1.0 |
| Marshelder | 1.5 | 0.4 | 25.0 | <0.1 | 3.2 | <0.1 | 1.5 | 1.0 |
| Common chickweed | 1.5 | 0.1 | 10.0 | 0.1 | 6.5 | <0.1 | 15.5 | 0.9 |
| Downy brome | 0.7 | 0.3 | 40.0 | 0.1 | 8.6 | <0.1 | 4.0 | 0.7 |
| Purslane speedwell | 0.7 | 0.2 | 30.0 | 0.1 | 8.6 | <0.1 | 6.0 | 0.6 |
| Biennial wormwood | 0.7 | 0.2 | 30.0 | <0.1 | 5.4 | <0.1 | 3.0 | 0.6 |
| Lanceleaf sage | 0.7 | 0.1 | 20.0 | <0.1 | 4.3 | <0.1 | 3.0 | 0.5 |
| Field sandbur | 0.7 | 0.1 | 20.0 | <0.1 | 2.2 | <0.1 | 1.0 | 0.4 |
| Sweetclover | 0.7 | 0.1 | 10.0 | <0.1 | 3.2 | <0.1 | 3.0 | 0.4 |
| Yellow woodsorrel | 0.7 | 0.1 | 10.0 | <0.1 | 1.1 | <0.1 | 1.0 | 0.3 |
| False chamomile | 0.7 | 0.1 | 10.0 | <0.1 | 1.1 | <0.1 | 1.0 | 0.3 |
| Weed free | 25.2 | 6.9 | 27.4 | - | - | - | - | - |
| Table 69. North Dakota weed infestations in previous crop of soybean, dry bean, lentil and field pea based on 197 surveyed fields, spring 2000. | ||||||||
| Weed | ||||||||
| Weed | Field Uniformity | Weed Density | Density Range | Weed | ||||
| Weed species | Frequency | All | Infested | All | Infested | Low | High | Index |
| (%) | (%) | (%) | - - Plants/m2 - - | - - Plants/m2 - - | ||||
| Green foxtail | 59.4 | 21.6 | 36.3 | 19.1 | 32.2 | 1.4 | 20.1 | 85.9 |
| Wild mustard | 53.3 | 16.9 | 31.6 | 5.9 | 11.0 | <0.1 | 4.1 | 48.3 |
| Yellow foxtail | 31.0 | 9.6 | 31.0 | 10.2 | 33.0 | 0.4 | 16.8 | 43.8 |
| Wild buckwheat | 46.7 | 15.8 | 33.8 | 4.5 | 9.6 | <0.1 | 3.7 | 41.8 |
| Common lambsquarters | 35.0 | 11.5 | 32.8 | 5.9 | 16.8 | <0.1 | 8.1 | 36.9 |
| Soybean | 44.2 | 14.5 | 32.9 | 2.6 | 5.9 | <0.1 | 2.3 | 35.3 |
| Kochia | 27.4 | 7.1 | 25.9 | 4.2 | 15.2 | 0.1 | 14.4 | 26.0 |
| Canada thistle | 36.0 | 8.2 | 22.7 | 2.3 | 6.4 | <0.1 | 3.2 | 25.6 |
| Pigweed species | 24.4 | 7.6 | 31.0 | 3.2 | 13.3 | <0.1 | 7.1 | 23.2 |
| Wild oat | 21.3 | 5.8 | 27.4 | 3.3 | 15.7 | 0.1 | 10.5 | 20.7 |
| Eastern black nightshade | 19.8 | 5.6 | 28.5 | 2.2 | 11.3 | <0.1 | 4.5 | 17.5 |
| Common ragweed | 20.8 | 5.8 | 27.8 | 1.8 | 8.6 | <0.1 | 3.6 | 16.9 |
| Common cocklebur | 15.2 | 4.5 | 29.3 | 1.2 | 7.7 | <0.1 | 3.1 | 12.3 |
| Wild-proso millet | 5.1 | 1.6 | 31.0 | 0.7 | 14.1 | <0.1 | 6.8 | 4.9 |
| Common milkweed | 9.6 | 1.2 | 12.6 | 0.2 | 1.9 | <0.1 | 1.5 | 4.9 |
| Perennial sowthistle | 5.6 | 1.4 | 25.5 | 0.5 | 9.0 | <0.1 | 3.8 | 4.5 |
| Field bindweed | 7.1 | 1.1 | 15.7 | 0.2 | 2.3 | <0.1 | 1.6 | 3.9 |
| Sunflower | 4.6 | 1.1 | 23.3 | 0.2 | 5.1 | <0.1 | 2.1 | 3.1 |
| Russian thistle | 3.6 | 1.1 | 30.0 | 0.3 | 7.7 | <0.1 | 2.7 | 2.9 |
| Quackgrass | 4.6 | 0.7< | ||||||