Syngenta Thrive

Field Insights

Test Your Weed Knowledge

Test your weed identification skills to protect yields from common corn and soybean weeds like waterhemp and Palmer amaranth.

Can you recognize common corn and soybean weeds? Characteristics like leaf shape, petiole length and the presence of hairs can help you identify these yield-robbers. Learn to tell the difference between these common weeds (including waterhemp and Palmer amaranth!) and put your knowledge to the test.

Plus, get fast facts about other weeds like horseweed, common lambsquarter and giant ragweed.

An infographic titled 'What's That Weed?' depicting Polaroid-style photos that feature silhouettes of various weeds, each with a description of that weed’s scientific name, life cycle, habitat, and appearance. The silhouette photos flip over to reveal a full-color image of each weed.

Waterhemp, aka Amaranthus tuberculatus. FAMILY: Amaranthaceae (Pigweed). LIFE CYCLE: Summer annual. HABITAT: Native to North America and widespread from central to eastern U.S. DESCRIPTION: Seedling leaves are oar-shaped;
true leaves are alternate, oval to lanceolate in shape (wider at base and taper toward leaf tip) and measure 0.5 to 6 inches long and 0.25 to 1.25 inches wide. Waxy, hairless stems and leaves with prominent veins and small notch at leaf tip. Brightly-colored stems range from red-pink to green.

Palmer amaranth, aka Amaranthus palmeri. FAMILY: Amaranthaceae (Pigweed) LIFE CYCLE: Summer annual. HABITAT: Native to Southwest U.S./Northern Mexico and is widespread throughout the country. DESCRIPTION: Seedling leaves more oval- or diamond-shaped; true leaves are alternate and lanceolate in shape, measuring 2 to 8 inches long and 0.5 to 2 inches wide. Smooth, hairless stems and leaves with prominent white veins on undersurface. Single hair located at leaf tip notch of first few true leaves can often (but not always) distinguish Palmer amaranth fromwaterhemp.

Horseweed, aka Marestail or Erigeron canadensis. FAMILY: Asteraceae (Composite) LIFE CYCLE: Winter and summer annual. HABITAT: Native to North and Central America. DESCRIPTION: Seedlings feature basal rosette with oval- to egg-shaped leaves; true leaves are alternate, linear, hairy and irregularly-toothed, measuring 4 inches long and 0.25 to 0.5 inches wide. Sessile leaf pattern, meaning no petiole is present. Leaves are progressively smaller towards top of stem.

Giant ragweed, aka Ambrosia trifida. FAMILY: Asteraceae (Composite). LIFE CYCLE: Summer annual. HABITAT: Native to North America and widespread from central to eastern U.S. DESCRIPTION: First pair of true leaves are unlobed and lanceolate in shape. All other subsequent leaves are 3-lobed or 5-lobed. Leaves are opposite and hairy with toothed margins, measuring 6 inches long and 4 to 8 inches wide.

Common cocklebur, aka Xanthium strumarium. FAMILY: Asteraceae (Composite). LIFE CYCLE: Summer annual. HABITAT: Exact origins debated; native to the Americas and possibly Eurasia. DESCRIPTION: Seedlings feature lanceolate leaves and purple stem base; first pair of true leaves appear opposite one another. Subsequent true leaves are alternate, triangular and ovate with stiff hairs and irregular margins, measuring 2 to 6 incheslong. Thick, rough stems featuring dark purple or black spots.

Common lambsquarters, aka Chenopodium album. FAMILY: Amaranthaceae (Pigweed). LIFE CYCLE: Summer annual. HABITAT: Believed to have originated in Eurasia. DESCRIPTION: Dull green color with mealy, whitish-gray coating on upper leaf surface. Seedling leaves are opposite and narrow with rounded tips, no veins visible. True leaves are alternate, triangular to lanceolate in shape with undulate to toothed margins.

July 2024 | Syngenta Thrive

2 Min Read

HIGHLIGHTS
  • Correct identification of weed species is crucial to help inform your herbicide decisions.
  • Some key weeds like waterhemp and Palmer amaranth can be difficult to tell apart.
  • Besides leaf shape, distribution, size and color, other characteristics like toothed leaf edges or the presence of hairs can aid in identification.

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