P&PDL Picture of the Week for
October 23, 2006

Foxtail in Title Only – Carolina Foxtail

Glenn Nice, Weed Diagnostician, Department of Botany & Plant Pathology, Purdue University

When the tail of foxtail is spoken of in Indiana, it is generally about the summer annual grasses, green, yellow, and the ever popular giant foxtails that is referred to. However, in reality the term foxtail is simply part of the common name game, a name tagged to several plants. A quick search using the word ‘foxtail’ on the USDA’s plant database and you get approximately 40 common names using the word “foxtail” covering several genera ranging from a pine tree to several grasses. 

Last spring we received several calls regarding Carolina foxtail (Alopecurus carolinianus Walt.). This foxtail, unlike the green, yellow and giant is a cool season native grass that will produce seed in the spring and early summer. Its distinguishing characteristic is its timothy-like seed head (figure 1). Many spikelets are crowded into a soft spike. Each spikelet has one flower. Although the seed spike looks like a tiny timothy, with closer inspection with a hand lens, one can see a small awn emerging from one side of the scale, timothy scales do not have this. Carolina foxtail is a short stature grass generally about 4 to 6 inches tall1.  It has a small membranous ligule, something else that distinguishes it from green, yellow and giant foxtails. Leaves are 2 to 5 inches long and 0.03 to 0.2 inches wide. 

For the most part, Carolina foxtail is not difficult to control. Research from Purdue reported Glyphosate (Roundup Weathermax, Touchdown, Glyphomax, etc) provided excellent control of Carolina foxtail (98%) when applied in the fall2. Although no benefit to the control of grasses, the addition of 2,4-D can be added to reduce selection pressure of glyphosate resistant marestail (horseweed). Canopy EX also provided excellent control (99%) of Carolina foxtail. Research done in Southern Illinois reported fall application of Basis and simazine controlled Carolina foxtail 100 and 96%, respectively3. Be aware that some herbicides applied in the fall have rotation restrictions that limit what can be planted the following year.

For the most part Carolina foxtail finishes its life cycle once the hot dry months of summer arrive; however, I have seen it in late June in Tippecanoe County. Mostly forgotten about in late summer, the best time to control Carolina foxtail is in the fall or early spring.

PHOTO Credit:

Figure 1.  Carolina foxtail seed head. Robert H. Mohlenbrock. USDA SCS. 1989. Midwest wetland flora: Field office illustrated guide to plant species. Midwest National Technical Center, Lincoln, NE. Courtesy of USDA NRCS Wetland Science Institute.

Figure 2. Carolina foxtail spikelet scale. Steve Hurst. Provided by ARS Systematic Botany and Mycology Laboratory. Peoria Heights, IL.

References

1Kansas Grasses, Kansas State University.  Accessed Oct. 23, 2006.   (http://spuds.agron.ksu.edu/digikey.htm).

22006 Annual Research Report.  Bill Johnson, Purdue University (not published).

3Winter Annual Weed Control with Fall-Applied Corn (Zea mays) Herbicides.  R.F. Krausz, B.G. Young, and J.L. Matthews.  Weed Technology: Vol. 17, No. 3, pp. 516-520.

 

Click image to enlarge

Carolina foxtail

Carolina foxtail seed

Purdue Plant & Pest Diagnostic Lab Purdue Cooperative Extension Service