Also known as disc mayweed, pineapple weed is an annual  herb and member of the aster family, Asteraceae, that also includes chamomile, daisies, and lettuce.  It is native to northeast Asia but was introduced into the US and now occurs in the compacted soils in gardens, unmowed areas,  waste areas, and along roadways in the eastern US and along the Pacific coast.  Plants prefer full sun and mesic conditions.

Description:  With a branching taproot, pineapple weed  grows up to eighteen inches tall with a  low branching habit.  It has fern like  pinnately compound leaves up to two inches long.  The flowerheads are produced in the axils of the upper leaves and are 1/3 inch  across. They consist of greenish yellow disk flowers  that are arranged into a dome shape and are surrounded by overlapping green bracts with papery margins.  Blooms appear during the summer for one to two months and are followed by an oblong achene. Both flowerheads and foliage have a pineapple aroma when crushed.  Plants spread by seed.

Control:  Mulch to prevent seeds from germinating; hoe or pull young plants as they appear. Pull, cut, or mow older plants before they set seed.  Although some herbicides are ineffective on pineapple  weed,  Dithiopyrn, Isoxaben, and  Simazine (preemergent), and Bromoxynil, and 2,4-D (post emergent), have been effective.

By Karen