HPIPM:Witchgrass

Taxonomy

Domain	Eukarya
Kingdom	Plantae
Phylum	Magnoliophyta
Class	Magnoliopsida
Superorder	Lilianae
Order	Poales
Family	Poaceae
Subfamily	Panicoideae
Tribe	Paniceae
Genus	Panicum

Scientific Name

Panicum capillare

Common Name

witchgrass

Witchgrass (Panicum capillare)

Compiled by Mary Rumph, Montana State University, Powder River County Extension

and Marjolein Schat, Montana State University from the following sources:

http://plants.usda.gov/java/profile?symbol=PACA6

http://www.ipm.ucdavis.edu/PMG/WEEDS/witchgrass.html

http://www.illinoiswildflowers.info/grasses/plants/witch_grass.htm

http://www.cdfa.ca.gov/PHPPS/ipc/weedinfo/panicum.htm

Identification and Life Cycle

Witchgrass (Panicum capillare) is an annual in the grass family (Poaceae). Other common names for witchgrass are panicgrass, ticklegrass, tumble panic, tumbleweed grass, and witches hair. Panic grass is a hairy, bushy plant branched from the base. Seedlings resemble those of crabgrass but have longer silky hairs with swollen bases. Mature plants are 1 to 2 feet tall. Sheaths are erect, reaching 32 inches in height, somewhat flattened, and covered with hairs. Sheaths have split margins that are overlapping. Leaves are 1/4 to 1/2 inch broad with fringed ligules and no auricles. Leaf blades have a conspicuous white midvein and are from 4 to 10 inches long, The large, open panicled inflorescence has spikelets that each bear a solitary seed at the tip of a branch. The panicle may range from 8 to 16 inches in length and may account for as much as half of the entire height of the plants.

Habitats

Habitats include disturbed areas of prairies (including sand and gravel prairies), limestone and sandstone glades, chert and granite glades, gravelly bars near rivers, gravelly areas along railroads (including the limestone ballast), fields, and barren waste areas.

Impacts

Witchgrass is primarily a weed of agronomic crops, gardens, and landscapes. Competition by witchgrass in newly planted fields of Kentucky bluegrass reduces vigor and stand of bluegrass seedlings and may significantly reduce seed yields the first harvest year. In some years a seeding may be lost.

Biology and Ecology

Most seed germinates from late spring through midsummer. Some seeds may germinate throughout the year under favorable conditions. The blooming period occurs during late summer and early fall. Shortly afterwards, the panicles and their spikelets become light tan. The entire panicle can detach from the plant and roll across the ground, like a tumbleweed, distributing the seeds. Seeds disperse to greater distances with human activities, soil movement, water, and as seed or hay contaminants.

Biological Control

There are no biological control agents available for witchgrass.

Mechanical and Cultural Control

Cultivation or mowing in late spring before seed develops can control infestations.

Chemical Control

In 1981 there were reports of witchgrass resistance to photosystem II inhibitors in Ontario Canada. For more information about this report, please see http://www.weedscience.org/Summary/USpeciesCountry.asp?lstWeedID=121&FmSpecies=Go

For herbicide recommendations for specific grain rotations and weeds in Montana, please see the MSU Herbicide Chooser Tool.

Examples of herbicides that can be used to manage witchgrass

Consult herbicide labels for additional rate, application, and safety information. Additional herbicide information can be found at http://www.greenbook.net.

Herbicide Active Ingredient trade name	Mode of Action	Product per Acre	Application Time or Growth Stage
Alfalfa
Clethodim	Inhibition of acetyl CoA carboxylase (ACCase)
*Select Max		9 - 16 ounces	Do not harvest for forage or hay or graze within 15 days after application. See label for tank mix recommendations.
Peas and Lentils
Pendimethalin	Microtubule assembly inhibition
* Prowl H2O		3 pints	May be applied 60 days prior to planting up to immediately before planting. After application, rotary hoeing and shallow cultivation/ tillage can be practiced without reducing weed control. Avoid tillage that will bring untreated soil to the surface.
Grass Grown for Seed
Pelargonic acid	Cell membrane disruption (Cellular pH disruption)
*Scythe		3 - 5% Spray solution	Apply for vegetative burndown for general control of weeds for seedbed and site preparation. Apply pre crop emergence or to dormant fields after harvest.
Winter Wheat - Preplant
Diclofop	Inhibition of acetyl CoA carboxylase (ACCase)
*Hoelon 3EC		2 - 2.6 pints	See label for specific state by state instructions. Apply preplant and incorporate to a maximum depth of 2 inches. Incorporate one time within 48 hours of application followed by a second incorporation in a different direction.
Wheat - Post Emergence
Diclofop	Inhibition of acetyl CoA carboxylase (ACCase)
*Hoelon 3EC		2 pints	Apply when weeds are in the 1 to 3 leaf stage. Do not apply less than 77 days before harvesting wheat.

The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.

References

For more information and images please visit IPM Bugwood. http://www.ipmimages.org/search/action.cfm?q=Panicum%20capillare&Start=1&results=18