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Strawberry

Windblown Weed Seed—Previous Crop and Preplant

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  • Hairy fleabane
  • Cudweed
  • Horseweed
  • Common groundsel
  • Annual sowthistle
  • Prickly lettuce
  • Milkthistle

These weeds produce seeds with a tuft of fine bristles, called a pappus, that allows the seed to be carried on wind currents. Survey previous crops, adjacent crops, and field borders for these weeds and control them before they produce seed.

Use the photos below to identify weeds in the field. Names link to information on identification and biology.

Click on photos to enlarge
Seedling Mature
Seedling of 		hairy fleabane
Hairy fleabane
(Conyza bonariensis): Sunflower family; summer annual or biennial; seed leaves gray green; first leaves narrow and covered with short, soft hairs; often wrinkled or distorted.
Hairy fleabane
Hairy fleabane
(Conyza bonariensis): Sunflower family; summer annual or biennial; erect stems usually branched at base; gray-green foliage covered with hairs; whitish flower heads; narrow, oblong seeds with brownish white fuzzy bristles.
Seedling of purple cudweed
Purple cudweed
(Gnaphalium purpureum): Sunflower family; winter annual, summer annual, or biennial; seed leaves and first true leaves covered on both sides with whitish hairs; seed leaves 2 to 3 times longer than wide.
Cudweed
Cudweed
(Gnaphalium spp.): Sunflower family; most species annual, purple cudweed a winter or summer annual or biennial; plants sparsely branched, erect; leaves linear, lance shaped, or spoon shaped, with woolly hairs; flower heads small and numerous, in dense clusters; oblong seeds with numerous fine, white bristles that detach at maturity.
Seedling of 				horseweed, Conyza canadensis, at the four-leaf stage.
Horseweed
(Conyza canadensis): Sunflower family; summer annual or biennial; 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.
Horseweed
Horseweed
(Conyza canadensis): Sunflower family; summer annual or biennial; erect, tall single stems that branch only in the upper half; foliage hairless to densely covered with thick short hairs; whitish flower heads; narrow, oblong seeds with dirty white fuzzy bristles.
Seedling of common groundsel, Senecio vulgaris.
Common groundsel
(Senecio vulgaris): Sunflower family; winter annual, but seedlings can be present anytime at cool, moist locations; seed leaves narrow, with blunt narrow tip; first true leaves with shallow teeth; third and fourth leaves more deeply lobed.
Common groundsel
Common groundsel
(Senecio vulgaris): Sunflower family; winter or summer annual; plants more or less erect, with single stems or branched at base; leaves narrow, elongated, with lobed margins; yellow flower heads clustered at stem tips, often nodding; light brown, cylindrical seeds ribbed, with numerous soft, white bristles.
Sowthistle seedling
Annual sowthistle
(Sonchus oleraceus): Sunflower family; summer or winter annual; seed leaves markedly stalked, almost spoon-shaped, rounded at tip and often have grayish powdery bloom; injured tissue bleeds milky white latex.
Annual sowthistle
Annual sowthistle
(Sonchus oleraceus): Sunflower family; winter or summer annual; erect plants with thick, hollow stems; leaves alternate with toothed margins, lower leaves deeply lobed, upper leaves smaller with basal lobes clasping stem; yellow flower heads clustered at stem tips; seeds strongly flattened, with numerous soft, fine, white bristles.
Seedling of 				prickly lettuce, Lactuca serriola.
Prickly lettuce
(Lactuca serriola): Sunflower family; summer or winter annual or biennial; seed leaves about 2 times longer than wide; first true leaves with rounded margins; injured tissue bleeds milky white latex.
Cudweed
Prickly lettuce
(Lactuca serriola): Sunflower family; summer or winter annual or biennial; erect stems, often one per rosette; leaves oval or lance shaped, narrower at the base, margins prickly toothed, midveins with stiff, prickly hairs; flower heads at the tips of openly branched flowering stems; seeds mottled brown, ribbed, with numerous white bristles attached via a beak the same length or longer than the seed.
Milkthistle seedling
Milkthistle
(Silybum marianum): Sunflower family; winter or summer annual or biennial; seed leaves broadly oval, thick, smooth; first true leaves alternate, oblong, margins with prickly teeth, upper surfaces with white markings.
Milkthistle
Milkthistle
(Silybum marianum): Sunflower family; winter or summer annual or biennial; erect plants with thick, hollow stems, may form dense stands; leaves are lobed with prickly teeth, upper surfaces shiny green with conspicuous white markings; flower heads with numerous pink to purple flowers; slightly flattened, lance-shaped seeds mottled black and brown with numerous white fuzzy bristles fused at the base to form a ring.

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