Weed Identification Introduction to Horticulture CDE Brandon Smith

Crabgrass  Summer annual grass  Germinates March through early May  Flowers and seeds extend like fingers  Two common species  Large crabgrass  Smooth crabgrass  Large crabgrass  Hairy leaves  Pale blue-green  2-6 inches long  Smooth crabgrass  Smooth leaves  Dull green  1-4 inches long, sharply pointed ends

Crabgrass Large crabgrass Smooth crabgrass

Crabgrass Notice the flowers emerging like fingers from base of stalk -> Wide leaves ^

Chickweed  Winter annual  Mat forming  Leaves are oval shaped  Leaves on lower parts of stem have petioles  Leaves on upper portions sit on stem  Weak stems  Flowers are white and star-shaped  Prefers cool, moist areas  Can survive in compacted soils  Broadleaf weed

Chickweed

Dallisgrass  Perennial grass  Coarse, fast growing  Warm season grass  Clumping, can grow up to 4 ft. high if left unmown  Seed stalks are approximately 1 ft. or larger  Flower head has 3-5 terminal branches  Leaf sheath is reddish and slightly swollen  Flowers will open out then droop  Leaf sheath can be pubescent at the base

Dallisgrass

Goosegrass  Summer annual grass  Germinates in spring, approximately 2 weeks later than crabgrass  Stems are pale at the base  Do not root at nodes as crabgrass does  Grows flat  Particularly troublesome in athletic field environments  Flowers occur in July and September  Flowers occur on fingers  Prefers full sun and can tolerate compated soils and poorly drained soils

Goosegrass

Crabgrass compared to goosegrass

Henbit  Winter annual  In the mint family  Square stems  3-12 inches tall  Green to purple stems  Leaves crinkled at edges  Lower leaves have petioles  Upper leaves attach directly against stem  February through June, henbit has ¾ inch tubular, purple flowers  Plants die down in summer  Seeds survive and sprout in fall

Henbit

Oxalis  Broadleaf perennial  More commonly a problem in ornamentals  Also called woodsorrel  Cool season is most noticeable, but can have new seedlings in summer  Slender stems, pronounced taproot  Blooms from May through September  ½ inch yellow flowers with 5 petals  Seed pods very noticeable, 1 inch long  When pods are dry they easily pop open to disperse seed up to 6 ft.

Oxalis

Spurge  Summer annual  Freely branched stems that are mat-forming  Leaves are small, oval, close to stem  Can have pubescence and small purple spots  Blooms June through October  Flowers small, clustered  Flowers located near bases of the leaves  Seeds germinate in temperatures ranging from 60 degrees F to 90 degrees F

Spurge

White clover  Creeping perennial  Large production of seeds  Can spread by creeping stems that root at the nodes  Leaves have 3 round leaflets that can have a faint, white crescent mark  Flowers May through September  Ball shaped flower heads with white or pink flowers  Can occur throughout growing season  Can thrive in moist, infertile soils  You probably have a large amount of this growing in your lawn  For luck, find a four leaf one of these

White clover

Wild garlic  Management practices mirror that for biennial and perennial broadleaf weeds  Small, dark green grass-like weed  Grows during winter and spring, then dies down  Leaves are hollow and slender  Also can be found in the lawn with great frequency  Leaves are almost completely round  Can sometimes bloom and produce seed  Sometimes referred to as wild onion  Very noticeable odor when leaves are damaged

Wild garlic

Yellow nutsedge  #1 Identification rule with nutsedge…..  SEDGES HAVE EDGES!  Perennial  Warm growing season problem  Pale green, upright sedge  Looks like grass  Spreads from rhizomes that produce tubers  Yellow green leaves are shiny and waxy on top and dull on back  Yellowish brown flowers are spikelets  Stem is triangular (rule #1)  Blooms from July to September

Yellow nutsedge

References  Ornamental and Turfgrass Pest Management. Produced by NC Cooperative Extension Service – NC State University, Cooperative Extension Service- The University of Georgia, Clemson Cooperative Extension Service- Clemson University.  NC State Turf Files website. NC State University.