The Enemy: Common groundsel (Senecio vulgaris)
Strategy: This is an annual weed that invades landscapes, gardens, edges of agricultural fields and other highly disturbed areas. Its multiple stems grow to about 18 inches tall. The leaves are deeply lobed, crispy and somewhat hairy. The lower part is usually purple looking on the underside of the leaves. The entire plant will look somewhat purple in early, cool spring. It produces multiple yellow flowers, with black-tipped bracts. When the head has gone to seed, it produces soft-looking plumes resembling a small cotton ball.
Attack: This annual produces thousands of seeds per plant and invades highly disturbed areas. It robs the soils of valuable nutrients and water. It is quite toxic to horses if found in a pasture or on the range. It can germinate multiple times throughout the season therefore re-establishing its seed numbers often.
Defense: Annuals are easy to control mechanically. Consider the amount of soil disturbance you may generate which increases seed germination, particular with this weed. If it is found in your garden, pulling it up in moist soil works well. If this is not feasible, use Roundup plus 2,4-D (50 percent solution) wiped onto the weed with a glove, paint brush or even a small spray bottle (2 percent solution) works best. Along the landscape or edges of fields, 2,4-D or stronger herbicides are great and will keep it under control. Controlling this plant for a couple of seasons will deplete the seeds in the soil and prevent future problems, though it takes a few years. Consider where you get your compost.