QUACKGRASS

QUACKGRASS Agro-pyron rep ens- Showingfoliage, nature of rootgrowth, seedheads, sec-tion of leaf illustratingauricle, and two viewsof seed. (Seed magni-fied two diameters.)

COOPERATIVE EXTENSION SERVICE i OREGON STATE UNIVERSITY CORVALLIS

Cooperative Extension work in Agriculture and Home Economics, F. E. Price, director.Oregon State University and the United States Department of Agriculture cooperating.Printed and distributed in furtherance of Acts of Congress of May 8 and June 30, 1914.

Extension Bulletin 734 Revised December 1962

QUACKGRASSAgropyron repens

Other names : Couchgrass, Wheatgrass, Witchgrass

REX WARREN, Extension Farm Crops SpecialistOregon State University

Description

QUACKGRASSis found in all sections of the

state and adapts itself to almost all soiltypes. It is not an arid-climate weed, how-ever, and is seldom found in Oregon in areaswith less than 12 inches of rain, except oncreek bottoms or subirrigated land. It is agrass that produces a fair quality of forageand hay, and is one of the best soil binders.Quackgrass is a serious weed where notwanted because it spreads rapidly and tendsto take possession of any field once it becomesestablished.

The Oregon Seed Law classes quackgrassas a prohibited noxious weed. Vegetable andcrop seeds containing quackgrass seed cannotbe sold in the state.

Quackgrass is a long-lived perennial plantreproducing from both creeping rootstocksand seeds. Its root systems develop from 2 to8 inches deep. Most of the roots are found atthe 4-inch level. At each joint of the root-stock there is a tough, brownish sheath hav-ing a scaly appearance. Branches are pro-duced at nearly every joint. The ends of therootstock are often very sharp. This sharpgrowing point will penetrate potatoes andsimilar objects. Stems are 11 to 3 feet tall.

CultivationCultivation is a practical and economical

way of controlling large infestations ofquackgrass on cropland. Two common meth-ods of control by cultivation are (1) dryplowing, followed by delayed cross harrowingand (2) normal plowing and frequent disc-ing or rototilling. Choice of method dependson the kind of tillage equipment available.

Control by dry plowing. Crop residueshould be removed for hay silage, or the

They are usually smooth and with 3 to 6joints. Leaves have auricles (claw-like fing-ers) which clasp the stem and ligules (paper-like growths between leaf and stem) 1/32inch long. Leaves are often covered withwhitish bloom.

Seedheads resemble those of ryegrass butthe groups of seeds (grain), like wheat, areattached with their flat side against the stem.Heads vary from 3 to 10 inches in length.Quackgrass seeds (grain), because of sim-ilar size, are difficult to remove from rye-grass, orchardgrass, fescue, and most wheat-grasses.

Method of spreadQuackgrass spreads by seeds and root-

stocks. The most common method of spread isby planting quackgrass seed with impuregrain or forage seeds. Once established in thefield, it is readily spread by the dragging ofrootstocks with farm machinery. Pasturefields containing quackgrass should be clippedearly if the clipped forage is to be fed. Whenquackgrass forage is used for either hay orbedding, quackgrass seeds are spread to cleanfields with manure.

Methods of Control

area should be pastured before the field isplowed. Plow the field in such a mannerthat the furrow slice is left on edge. Thisis best accomplished by plowing with amoldboard plow.

Plowed fields should be left rough for3 to 4 weeks, exposing roots of quackgrassto the sun and wind. After 3 to 4 weeks,the quackgrass area should be cross-har-rowed, using a spring-tooth type harrow. Donot use a disc. The harrow pulls the plantroots to the surface, exposing them to

further drying. If the roots are numerous,they should be raked and burned. Reharrowthe area as often as quackgrass makesregrowth. Each harrowing should be done atright angles to the previous harrowing.

Control by discing or rototilling.Discing or rototilling cuts the quackgrassroots in small pieces which cannot be pulledto the soil surface for drying. When thismethod of tillage is used, the field is plowedshallowly and worked down with a disc orother cutting implement. Soil moisture ismaintained to encourage rapid growth of thecut quackgrass root sections. The area shouldbe reworked every time the new growth is 10days old. Continued working kills the newgrowth.

The cultivated field, whether dry plowed ornormally worked, should be seeded in theearly fall to adapted grain or forage crops.The crop planted should be seeded approxi-mately 30% heavier than for normal planting.Actual nitrogen at 20 to 30 pounds per acre,applied at the time of planting, will increasethe growth of the planted crop and providemore competition for the quackgrass. Theplanted crop should be removed for either hayor silage in the following spring. Immediatelyafter the crop is removed, the land should betilled in a manner similar to the previousyear's treatment.

Dry plowing following the harvesting offall-sown crops helps control light infesta-tions of quackgrass. With this control method,the field should be plowed immediately afterharvest, and the surface should be left rough,thus exposing the quackgrass roots. The fieldshould be cross-harrowed in approximately3 weeks. Straw from harvested crops must beremoved before plowing, otherwise it will bedifficult to pull the quackgrass roots to thesurface by harrowing.

Chemical control

Chemical control is usually limited to spotapplication, but some chemicals show realpossibilities of selective control when used ina cropping program with spray-tolerant crops.Most chemicals give better control in mineralsoils than on peat-type soils. More respray-ings are needed on peat soils.

Dalapon. Quackgrass can be controlledwith dalapon. The quackgrass should be

sprayed while there is enough soil moistureto provide active plant growth. An applica-tion of 10 pounds of dalapon per acre in 10or more gallons of water is recommended.For spot treating use 1 pound in 10 gallons ofwater. For eradication, the patch should be

resprayed with 5 pounds of dalapon peracre. This respraying should be done as oftenas green growth shows on the sprayed quack-grass. It is important to add a commercialwetting agent to the spray material. If cropsare to be grown in the dalapon-treated area,the area should be plowed 1 to 2 weeks aftertreatment and not planted for at least 4 weeksafter treatment.

Amitrole T (Amitrole or Cytrol). Likedalapon, amitrole T does not completely con-trol quackgrass with one application. Use 2gallons (4 pounds) of amitrole T in 10 gal-lons of water when applied with a boomsprayer. Use pound (1 quart) in 10 gallonsof water for spot treatment. Add a commer-cial wetting agent to the amitrole T spray.

Amitrole T can be applied any time there isgreen foliage present. Best results experi-mentally in western Oregon and irrigated sec-tions of eastern Oregon have been obtainedfrom early fall treatment.

Selective controlAmitrole T. Two gallons (4 pounds) of

amitrole T (Cytrol, Amitrole) can be used asa preplanting treatment for corn. The areashould be sprayed 10 to 14 days before thefield is plowed. Corn can be planted immedi-ately after plowing. Livestock should be keptout of the treated area.

Dalapon. Dalapon at 8 pounds per acre iseffective for controlling quackgrass whenused before planting corn. Spray the quack-grass when it is from 4 to 6 inches tall, thenwait 4 to 6 days after spraying before plow-ing. The corn should not be planted for 4 to 5weeks after plowing. Longer periods areneeded between plowing and corn plantingwhen the soil is excessively dry.

Atrazine. Atrazine is effective in selec-tively controlling quackgrass in sweet andfield corn fields. For best control, 3 pounds ofthe 80% atrazine should be sprayed on thequackgrass-infested field 3 weeks prior toplowing. Good control has been obtained when3 pounds of atrazine has been worked intopreviously plowed land before corn was

planted. A second application of 2 pounds of80% atrazine after planting kills surfacegerminating weed seeds and helps control themore persistent quackgrass plants. Many cropplants are damaged from residues of 3 to 5pounds of atrazine. For effective quackgrasscontrol on corn land, it is advisable to growcorn for 3 consecutive years. The field shouldbe treated the first and second years withatrazine, as previously outlined. No treatmentshould be made the third year. During thethird year, atrazine soil residues disappear,leaving the soil safe for planting to sensitivecrops such as oats, sugar beets, and manyvegetables.

Amitrole T and atrazine. A combinationof amitrole T and atrazine has given almostcomplete control of quackgrass in corn. Use2 pounds (1 gallon) of amitrole T. Thisshould be applied when the quackgrass is 4to 8 inches tall and growing actively. The in-fested field should be plowed 1 to 2 weeksafter the application of the amitrole T andafter the quackgrass has turned yellow orwhite. Corn may be planted immediately afterplowing. If corn is not planted immediatelyafter plowing, the soil should be worked toprevent any regrowth of quackgrass. Atrazineat 2 pounds of product per acre should be ap-plied on the corn as a pre-emergent or veryearly post-emergent treatment of the corn.This is the same atrazine treatment that isrecommended for annual weed control. Formaximum control, one cultivation is recom-mended when the corn is 4 to 8 inches tall.

Eptam. Eptam is effective in quackgrasscontrol when thoroughly incorporated intothe soil before resistant crops are seeded.Crops resistant to 4 pounds (5.3 pints) peracre are alfalfa, red clover, beans, and pota-toes. Eptam should be applied to a dry soilsurface and incorporated 5 to 6 inches deepin the soil. Discs are more effective for deepincorporation than are rototillers. Harrowsshould not be used when incorporating Eptamfor quackgrass control. The treated areashould be disced twice. The second discingshould be at right angles to the first discing.The chemicals should be applied with 20 to100 gallons of water per acre and incorpor-ated immediately. Alfalfa, red clover, beans,or potatoes can be planted immediately aftertreatment. There will be a slight retarding

effect on the planted crop, but resistant cropssoon recover from the effect of the Eptamtreatment.

Soil sterilantsKarmex diuron, Telvar monuron, simazine,

or atrazine are effective chemicals at heavyrates for eradication of quackgrass. Thesechemicals should be applied at the rate of30 pounds of the 80% chemical in 20 or moregallons of water per acre. For spot spraying,use .1 pound per gallon of water for eachsquare rod treated. Promotone at 32 pounds(16 gallons) has given effective quackgrasscontrol on peat soils in the Klamath Fallsarea. This material controls quackgrass onboth peat and mineral soils in low rainfallareas. These chemicals kill quackgrass slowly,and result in sterile soil for 2 to 5 years. Thelength of soil sterility depends on the rainfallor irrigation in the area treated.

Sodium chlorate and borate combinationsare effective for spot removal of quackgrass.The rate varies from 4 pounds per square rodwith chlorates to 12 pounds per square rodwith borates. Users should follow the recom-mendations on containers. Sodium chlorate isinflammable and should be applied dry.Clothes and equipment should be thoroughlycleaned immediately after treatment.

Soil fumigantsMethyl bromide and carbon bisulphide are

excellent chemicals for the control of quack-grass. Their use is confined to intensive areassuch as lawns, nursery beds, etc. Methylbromide requires covering of the treated areaat the time of application. Carbon bisulphideis injected directly into the soil with specialequipment. Areas treated with both of thesematerials can be seeded within 2 weeks.

SmotheringQuackgrass can be eradicated by flooding

with water or by covering the infested areaswith paper, canvas, or similar material. Thecovering must be kept over the quackgrassplants for at least one year.

Flooding is practical where large quanti-ties of water are available and where infestedareas are level enough so that dikes can bemade to hold water. The quackgrass must becompletely under water for 12 to 15 monthsfor effective eradication.