Common Mallow

Common mallow

The issue: Common mallow or cheese weed (Malva neglecta) is a non-native weed that will germinate from spring through fall. Fall-germinated seedlings will overwinter and continue growth during the next spring. While it is an all-season annual, it may behave more like a biennial or even a short-lived perennial. The cotyledons (seed leaves) are heart-shaped and the true leaves are nearly round with scalloped margins. The seed head is disc-shaped, and individual seeds are like a wedge that separates from the disc. Common mallow has a deep, tough taproot.

Common mallow invades disturbed areas, yards and gardens, pastures, no-till fields, ditch banks and rights-of-way. It only reproduces by seed, so all control efforts should be focused on keeping it from going to seed.

Integrated pest management options:

· Mechanical: Tilling, digging, hoeing, and field cultivation of common mallow works very well year-round. Hand-pulling is also very effective, although the taproot makes pulling mature plants quite difficult. If the plants have seed heads, throw them away rather than leave them lying on the ground. A weed burner used on seedlings in the fall can be effective, but is less effective on more mature plants.

· Cultural: Encourage competition from desirable plants.

· Biological: None available, but grazing young plants delays flowering.

· Chemical: Herbicides formulated for home use are not very effective on common mallow. 2,4-D, applied to seedlings, would be the most effective. In pastures and rights-of-way metsulfuron and chlorsulfuron (Escort & Telar) would be a better choice. Applying horticultural vinegar to seedlings may be effective. Be sure the target weed and crop or landscape situations are listed on the product label. Always read and follow herbicide label directions.

Combine them:

Weed control should be on our minds throughout the year. Combine different IPM options to help improve the effectiveness of your efforts.

For more information, contact Ron Patterson, University of Idaho Extension horticulture/agriculture educator in Bonneville County.