THE ISSUE:   Pineappleweed

  Pineappleweed (Chamomilla suaveolens) is a common summer annual broadleaf plant. Found commonly in gardens, lawns, cropland, and open spaces, pineappleweed thrives in harsh soil conditions such as compacted soils and high traffic areas, but not in shade. Pineappleweed germinates in early spring and continues to germinate throughout the year. Flowers can be present all year beginning in late spring. 

With lacey leaves and a pineapple smell, pineappleweed is easily identified. Cotyledons are bright green, narrow, thick, and fleshy, pointed or rounded at the tip, hairless, and are about 1/12 to ½ of an inch long and 1/25 of an inch wide. The leaves of the first pair are opposite to one another on the stem, hairless, and their leaf edges range from smooth to deeply lobed. Subsequent leaves are alternate to one another along the stem, deeply lobed to deeply divided into narrow fingerlike lobes, and form a stem. Seedlings grow as a rosette, then the plant branches upward into a small bush (6-12 inches high). Flower heads are found at the ends of stems, are egg shaped, and are composed of densely packed, tiny, non-showy, yellowish green flowers.

Integrated Pest Management (IPM) Options:  

• Prevention – Learn to identify this plant. Never transport unknown plant material. Effective prevention includes maintaining healthy, competitive desirable vegetation. 

• Mechanical – Hand-pull plants in planting beds prior to seed development.

• Chemical – Pre-emergent herbicides may not be effective since pineappleweed germinates year-round. Apply an appropriate post-emergent herbicide directly to target weeds. Many restricted and non-restricted use herbicides are available, for more information visit https://pnwhandbooks.org/ then search “pineappleweed” in the weed section. Always read and follow herbicide label directions!

Tom Jacobsen, University of Idaho Extension Educator in Fremont County. (208) 624-3102
[email protected]