Prohibited Noxious Weeds These 11 weeds MUST be controlled on all land in the state under the noxious weed law.. Garlic Mustard (Alliaria petiolata) Hemp, marijuana (Cannabis sativa)Plumeless thistle (Carduus acanthoides)Musk thistle (Carduus nutans)Canada thistle (Cirsium arvense)Bull thistle (Cirsium vulgare)Field bindweed (Convolvulus arvensis)Leafy spurge (Euphorbia esula)Purple loosestrife (Lythrum salicaria)Perennial sowthistle (Sonchus arvensis)Poison ivy (Toxicodend9447
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1. Noxious Weeds in Mille Lacs County Identification and Control
2. Prohibited Noxious Weeds These 11 weeds MUST be controlled on all land in the state under the noxious weed law.
Garlic Mustard (Alliaria petiolata)
Hemp, marijuana (Cannabis sativa)
Plumeless thistle (Carduus acanthoides)
Musk thistle (Carduus nutans)
Canada thistle (Cirsium arvense)
Bull thistle (Cirsium vulgare)
Field bindweed (Convolvulus arvensis)
Leafy spurge (Euphorbia esula)
Purple loosestrife (Lythrum salicaria)
Perennial sowthistle (Sonchus arvensis)
Poison ivy (Toxicodendron radicans)
3. Garlic Mustard (Noxious) Biennial (1st year rosettes are 4” high)
Shade tolerant (woodland)
Has a mustard-like appearance & garlic scented when crushed
Leaves have distinctive triangular shape with squared off base
4. Garlic Mustard First year plants Avoid spraying in early spring when native wild flowers are present
Cut plants close to the ground before they flower (April)
Looks like Creeping Charlie but smells like garlic
5. Garlic Mustard (Noxious) CONTROL:
Attack early, before it has a chance to become widespread
Small infestations can be readily controlled by pulling
6. Garlic Mustard Seed Heads Biennial, only spread by seed
Control strategies must center on depleting seed bank
Cut flower heads can still produce seed
Cut flowers and seed heads must be bagged and removed
Clean shoes, clothing and tools after working in infested area.
7. Leafy Spurge (Noxious) Perennial
Most visible mid-May (lime green)
Toxic to livestock (except sheep & goats)
Leaves and stem contain milky latex
2’tall & spread by underground rhizomes as deep as 15’+
Seeds mature July-September, capsule may pop seed up to 15 feet away
8. Leafy Spurge (Noxious) CONTROL:
Preventing the spread is the best plan!
Soils from infested lands should never be transferred to new areas for agricultural or construction purposes. Hay from infested pastures should never be taken off site. Additionally, machinery that passes through leafy spurge infestations should be thoroughly checked over, and sprayed down if possible, prior to entering another field.
9. Leafy Spurge Control
10. Biological Control Leafy Spurge
11. Poison Ivy (Noxious) Native, woody, perennial
Causes blistering of the skin
All parts of plant cause blistering of the skin: If burning poison ivy, do not inhale fumes!
Not all plants will flower or bear fruit (round, white, hard berries)
Bright green leaves turn brilliant red or orange in the fall
12. Poison Ivy (Noxious) CONTROL:
Burning produces soot particles which carry the oil into the air.
Poison ivy is best controlled with a brush killer herbicide. Apply it directly to leaves
Apply the herbicide when poison ivy is growing actively. You may have to spray more than once since poison ivy is a tough plant to kill.
13. Marijuana/Hemp (Noxious) Annual
2 to 10 ft tall
Entire plant is odiferous (smelly!)
Coarse, grooved, rough, hairy stems
Leaves are palmately divided into 5 to 11 leaflets
Flowers from July to September
14. Marijuana/Hemp (Noxious) CONTROL:
Pulling, cutting, tilling, repeated close mowing, etc., before seeds are produced
Chemical control when plants are young and actively growing
15. Purple Loosestrife (Noxious) Perennial
Is an escaped ornamental
Stem four sided & grows 4 to 6 ft
Over 2 million seeds may be produced by an average mature plant
Flowers from July to September
Reproduces by seed, underground roots & can spread by sprouting from pieces broken off the plant
16. Purple Loosestrife (Noxious)
Pulling or digging before plants go to seed. Be sure to remove ENTIRE plant as root and stem fragments can sprout
Chemical control applied in fall. Be sure herbicides are approved for use in or near water!
17. Perennial Sowthistle (Noxious) Creeping, rooted perennial
2-7 ft, reproduces by seeds & underground roots
All plant parts filled with bitter, milky juice
Leaves are slightly toothed and have weak, marginal prickles
Yellow, 1” flowers, June - August
18. Perennial Sowthistle (Noxious) CONTROL:
Grazing or repeated cutting, mowing, or cultivation will reduce seed production but may not eliminate plants.
Chemical control can be used in fallow fields or non-cropland
A combination of methods using herbicides, cultivation, and competitive crops may be most effective in cropland
19. Perennial Sowthistle
20. Canada Thistle (Noxious) Perennial - 2 to 5 feet tall
Reproduces by seed, but mainly by roots which send up new shoots
New shoots can arise from creeping roots 8” deep & from fragments as fast as 5 days
Plant can accumulate toxic levels of nitrates
Flowers June – Sept. & seeds mature 8-12 days after full bloom
Seeds may be viable in soil up to 20 years
21. Canada Thistle (Noxious) CONTROL:
Herbicides are most effective when applied to rosette stage in late September or early October.
Tillage is effective if cultivated before thistles are 3” tall and repeated before regrowth reaches 3” all season until freeze-up
Vinegar at 5 % acetic acid concentration has variable results
22. Canada Thistle Late Summer
23. Bull, Musk & Plumeless Thistle (Noxious)
24. Bull thistle
25. Musk Thistle
26. Plumeless Thistle
27. Bull, Musk & Plumeless Thistle biennial CONTROL:
Avoid overgrazing pastures
Reproduce by seed
Mow prior to flower development (June -ish)
Chemical is most effective if applied in the rosette stage (spring and fall)
28. Flodmans Thistle (Cirsium flodmanii) Minnesota Native Thistle
Single stem covered with white fuzz
Underside of leaves have whitish fuzz
1” wide head with rounded base
29. Field Bindweed Extensive root system, may penetrate 20 to 30’ into soil
Grows prostrate or will climb any object or plant
Spreads by seed or root
Perennial twining vine
Arrowhead shaped leaves
Problem in uncultivated areas
Flowers May - September
30. Field Bindweed Not extensive in Mille Lacs County
repeated cultivation and tillage during flowering season
Fall application of
31. County Secondary Weeds These weeds MUST also be controlled in Mille Lacs County
Giant Foxtail (Setaria faberii)
Wild Mustard (Brassica kaber)
Velvetleaf (Abutilon theophrasti)
32. Giant Foxtail (County secondary) Annual
Reproduces by seed
Branches at base
Leaves covered with short hairs on upper surface
Plants may fall over unless supported by each other or other vegetation
Often found nodding when mature
33. Giant Foxtail (County secondary) CONTROL:
Control recommendations vary with crop
Often present during land transition from Agriculture to Residential:
Mow prior to seed head development
34. Velvetleaf (County secondary) Annual
Reproduces by seeds
6-8 feet tall
Soft velvety, heart shaped leaves
Flowers July to October or till first killing frost
Mature seed present 3 weeks after flowering
Produces allelopathic chemicals which inhibit germination or growth of other plants.
35. Velvetleaf (County secondary) CONTROL:
Difficult to control
Herbicides can be effective, depending on the crop
Crop rotation prevents the formation of continuously favorable habitat.
Remove new plants before they produce seed.
Shallow cultivation about 3 weeks after planting will uproot seedlings.
36. Wild Mustard (County secondary) Flowers from May to July
Annual; winter annual
Reproduces by seed
Often a problem on Ag land
Palatable to animals in young stages, but seeds may cause serious illness in livestock if ingested in large quantities.
37. Wild Mustard (County secondary) CONTROL:
Can be controlled by mechanical cultivation of emerged seedlings.
However, cultivation of infested land is often impossible since wild mustard seed germinates at about the same time as spring planted annual crops.
Chemical control recommendations vary with crop
38. Duties of Local Weed Inspectors Public notice to control
Tours and inspections
39. Enforcement steps
Examine all lands within your jurisdiction.
Contact individuals in person or by letter to informally notify them of their noncompliance.
When informal notification fails, use “individual notice” to formally enforce the law.
Issue permits to transport infested material or equipment.
Submit reports and attend meetings as required.
Reports: Annual County Weed Meeting
Meetings: Annual County Weed Meeting