Giant foxtail, Setaria faberii
Weed Control Options 
Life Cycle
AnnualPropagation
Reproducing only by seed.Stems
Up to 2 m high, smooth.Leaves
Leaf sheaths mostly smooth, except hairy along the margins; leaf blades 30 - 55 cm long, 3 - 17 mm wide, usually finely hairy throughout the entire upper surface (G, H) of all leaves and occasionally also on the undersurface (seen by rolling the leaf over a finger and viewing it against the light); ligule a dense band of hairs, about 1.0 mm long; no auricles.Flowers and Fruit
Inflorescence dense, spike-like, erect or the larger ones usually somewhat curved or nodding, 4.5 - 17 cm long and 1.5 - 3 cm thick, surrounded by light yellowish-green awn-like bristles which give the inflorescence a bottle-brush appearance; spikelets 1.5 - 3 mm long; grains (“seeds”) light green and abundantly cross-wrinkled. Flowers from late July to October.Roots and Underground Structures
Fibrous root system.Habitat
Giant foxtail is native to China and was recently introduced from the USA where it is a very common weed; it is becoming abundant in fields and waste places in southern and eastern Ontario.Competitiveness
Corn yield loss (%)*:2 % at 1 plant/m2
10 % at 5 plant/m2
Soybean yield loss (%)*:
3 % at 1 plant/m2
12 % at 5 plant/m2
*assumes that the weed has emerged with the crop and has been left uncontrolled all season.
Distinguishing Features
It is distinguished from Green foxtail by its usually larger, nodding inflorescence, its distinctly cross-wrinkled grains and usually hairy upper surface of leaves, and from Yellow foxtail by its larger, greenish-yellow rather than orange-yellow inflorescence, and by the upper surfaces of its leaf blades being finely short-hairy throughout their length rather than bearing a few long, kinky hairs near the stem. The technical character that distinguishes Giant foxtail from Green foxtail is that its second or upper glume covers only about ¾ of the fertile floret, whereas in Green foxtail it covers nearly the entire floret.Toxicity
Giant foxtail is not known to be toxic.Human Health Issues
Giant foxtail is not a known allergen.Forage Quality
No information exists at this time.Species Benefits
No information available at this time.Often Mistaken For
Green Foxtail (SETVI), Fall Panicum (PANDI)Power Ranking Corn
Power ranking↑ 11
Power Ranking Soybeans
Power ranking↑ 12
Biological Control
Currently none available for this weed. For the latest research on biological weed control: Click here
Biopesticide Control
Currently none available for this weed.Herbicide Resistance
Populations resistant to sulphonylurea and imidazolinone (WSSA group 2)herbicides exist in Lambton county (ON).For more information on weed resistance:
Click here
Media Items
Figure 1: Giant foxtail: G. Yound plant showing finely hairy leaf surfaces. H. Leaf-base showing dense covering of very short hairs on upper surface of leaf-base, hairy ligule with longer hairs at margins of collar, and short hairs along edge of leaf sheath. Top
Figure 2: Ligule: hairy. Top
Figure 3: Leaf blade: Hairy upper leaf surface and hairless lower leaf surface. Top
Figure 4: Leaf sheath: Hairy margins. Top
Figure 5: Seed head. Top
Figure 6: Entire plant. Top