Michigan law regulates the sale, advertising, or transport of certain noxious weeds. Noxious weed seeds are generally considered to be serious nuisances or economically detrimental and are divided into two categories. Prohibited noxious weed seed cannot be sold or transported in the state. Restricted noxious weed seeds are only permitted when strict limits on the percentage or number of such seeds found in any lot of seed are observed.

The various Acts and Regulations that pertain to the sale or transport of seed consisting of or containing noxious weeds are summarized below:

• Act 329 of 1965 – Michigan Seed Law – includes limit on percentage of weed seed
• Regulation 715 – Seed Law Implementation – list prohibited and restricted noxious weeds

A complete list of the prohibited and restricted noxious weed seeds covered by Regulation 715 follows:

Prohibited Noxious Weeds

• Bindweed, Field - Convolvulus arvensis
• Bindweed, Hedge - Convolvulus sepium
• Dodder - Cuscuta species
• Horsenettle - Solanum carolinense
• Johnsongrass - Sorghum halapense, including sorghum almum and seed which cannot be readily distinguished from Johnsongrass
• Knapweed, Russian - Centaurea picris
• Knapweed, Spotted - Centaurea maculosa
• Morning glory, Ipomoea species
• Nutsedge, Yellow - Cyperus esculentus, both seed and tubers
• Puncturevine - Tribulus terrestris
• Quackgrass - Agropyron repens = Elytrigia repens
• Sowthistle, Perennial - Sonchus arvensis
• Spurge, Leafy - Euphorbia esula
• Thistle, Bull - Cirsium vulgare
• Thistle, Canada - Cirsium arvense
• Thistle, Musk - Carduus nutans
• Thistle, Plumeless - Carduus acanthoides
• Tussock, Serrated - Nasella trichotoma
• Whitetop = hoary cress = perennial peppergrass - Cardaria draba

Restricted Noxious Weeds

• Alyssum, Hoary Berteroa incana
• Carrot, Wild - Daucus carota
• Charlock - Sinapis arvensis
• Cocklebur - Xanthium strumarium
• Dock, Curled - Rumex crispus
• Fanweed, Thlaspi arvense
• Foxtail, Giant - Seteria faberii
• Garlic, Wild - Allium vineale
• Jimsonweed - Datura stramonium
• Mustard, Black - Brassica nigra
• Mustard, Indian - Brassica juncea
• Nightshade complex, including all of the following Solanum species and any other species with indistinguishable seed: (i) Bitter nightshade, Solanum dulcamara. (ii) Black nightshade, Solanum nigru. (iii) Eastern black nightshade, Solanum ptycanthum. (iv) Silverleaf nightshade = purple nightshade, Solanum eleagnifolium. (v) Hairy nightshade, Solanum sarrachoides.
• Oat, Wild - Avena fatua
• Onion, Wild - Allium canadense
• Plantain, Buckhorn - Plantago lanceolata
• Radish, Wild -Raphanus raphanistrum
• Rocket, Yellow - Barbarea vulgaris
• Velvetleaf - Abutilon theophrasti

The number of restricted noxious weed seeds that may be found in any particular lot of seed is limited to 1 seed of any or all of the restricted noxious weed seeds to 2,000 seeds of the seed sold, offered, exposed, or transported for sale, except that for buckhorn and yellow rocket, the limit shall be 1 seed to 1,000 seeds of the seed sold, offered, exposed, or transported for sale.

If present in a lesser ratio, the seed consisting of or containing the restricted noxious weeds may be sold, provided that the name of the restricted noxious weed(s) must be named on the tag together with the number of the restricted weed seeds per pound, unless they are buckhorn or yellow rocket. If the restricted noxious weeds are either of these, they need not be shown on the tag unless they exceed 90 seeds per pound.