Agriculture: Walnut Pest Management Guidelines

Summer Annual Weeds

Names link to more information on identification and biology.

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Seedling of barnyardgrass, Echinochloa crus-galli.
Barnyardgrass
(Echinochloa crus-galli) Grass family; summer annual; first leaf dull gray-green; stem flattened, purplish; no ligule.

Bearded sprangletop seedling, Leptochloa fascicularis.
Bearded sprangletop
(Leptochloa fasicularis): Grass family; summer annual; first leaves light green, usually with white midrib; blades somewhat rolled; sheaths loose near base of plant; ligule long, thin, membranous and tears easily.

Seedling of California burclover
Common knotweed
(Polygonum arenastrum): Knotweed family; summer annual; seed leaves are long, very narrow, rounded at the tip and light green with a white cast; true leaves are much broader, emerging from an encircling, membranous sheath at the leaf base.

Seedling of common purslane, Portulaca oleracea.
Common purslane
(Portulaca oleracea): Purslane family; summer annual; seed leaves oblong, somewhat club shaped, succulent, maroon on lower surface, and green or maroon on upper surface; young leaves smooth, succulent, oblong, green on upper surface, maroonish underneath, and broadest around leaf tip, with short petioles.

Photo not available.
Fall panicum
(Panicum dichotomiflorum): Grass family; summer annual; the first leaf blade opens parallel to the ground, is lance shaped to linear, and about 5 times longer than wide; leaves are rolled in the shoot; ligule is a fringe of hairs, collars are very hairy, and auricles are absent; lower leaf blade surface is hairy, upper surface is without hair.

Seedling of  				hairy fleabane, Conyza bonariensis, at the four-leaf stage.
Hairy fleabane
(Conyza bonariensis): Sunflower family; summer annual; seed leaves gray-green; first leaves narrow and covered with short, soft hairs; often wrinkled or distorted.

Seedling of horseweed, Conyza canadensis, at the four-leaf stage.
Horseweed
(Conyza canadensis): Sunflower family; summer annual; seed leaves dull green, oval with fine hairs, and with short stalks that sometimes may be tinged brown-purple; first true leaves covered with hairs on upper surface and margins; undersides of early leaves smooth.

Crabgrass seedling.
Large crabgrass
(Digitaria sanguinalis): Grass family; summer annual; first leaf blade linear to lance shaped, with stiff, jagged, and papery ligule; hairs on margins of the collar wide; no auricles; leaves covered with coarse hairs; leaves rolled in bud.

Puncturevine seedling.
Puncturevine
(Tribulus terrestris): Caltrop family; summer annual; seed leaves thick, brittle, 2 to 3 times longer than wide; petioles pinkish; true leaves dark green with grayish underside and rough margins.

Spotted spurge seedling.
Spotted spurge
(Chamaesyce maculata): Spurge family; summer annual; seed leaves oval, tips roundish, blue-green with smooth margin; first true leaves rounded, leaf surface smooth and dull, dark green with reddish tinge.

Witchgrass
Witchgrass
(Panicum capillare): Grass family; summer annual; light green to red-purple and resembles crabgrass seedling but has slightly narrower leaf blades and longer silky hairs with swollen bases.

 

Text Updated: 12/07
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