Illustration: Common Weeds of the United States
Smallflower galinsoga (Galinsoga parviflora), an annual weed, is also most appropriately known as quickweed because it reproduces quickly from seed. Quickweed plants are capable of producing multiple generations each growing season because their seeds have no dormancy requirements.
The erect, branching stems of quickweed ultimately reach a height of 1-2 feet but the plant will bloom when it's only a few inches tall, well before it reaches maximum size. Its tiny, daisy-like flowers each have five white petals (ray flowers) around the edge of a yellow center. Quickweed leaves are oval to lance-shaped with pointed tips; they're positioned opposite each other on the stem.
The most effective way to control quickweed in the garden is to hand pull or hoe out any plants as soon as you see them. If possible, remove them before flowers appear in order to prevent seed formation. Weeding must be continued all summer long to be effective, as seeds already in the soil continue to germinate through spring and summer.
Mulching the garden helps control all weeds as well as conserve soil moisture, and protect soil structure. Maintain a level of 2 to 4 inches of mulch once soil temperatures warm in mid- to late June. Straw, grass clippings or compost all make excellent mulch materials.
To achieve some chemical control, apply an appropriate pre-emergent herbicide. Bensulide (Betasan), DCPA (Dacthal), and trifluralin (Preen) are labeled for use in gardens. Benefin (Balan) and siduron (Tupersan) are labeled for use in turf only. Read the label carefully to determine if reapplication is necessary during the season.
Pre-emergent herbicides will prevent not only weed seeds from sprouting but also seeds from many desired plants. The best time to apply pre-emergent herbicides is after the preferred plants are up and growing and transplants have had a week or so in which to send out new roots. Read the label carefully to determine if the product is approved for use with the plants in your garden, and as always READ AND FOLLOW LABEL DIRECTIONS CAREFULLY.