reed canary grass

(Phalaris arundinacea)

 

Invasive implications

There are conflicting reports as to whether reed canary grass is native to specific areas of the Northwest or introduced from Eurasia by Euro-American settlers. Regardless, it is evident that Phalaris arundinacea has hybridized with introduced variations of this species, creating numerous strains that grow under a wide range of environmental conditions. To complicate matters, reed canary grass is still widely used for pastures and soil-erosion prevention and is common in grass seed mixes. Consequently, this cool-season perennial has run rampant in southern B.C., choking streams, irrigation ditches, and wetlands. Reed canary grass is very aggressive and capable of rapid and near total dominance over native wetland plant communities. It is particularly threatening to disturbed sites where it can single-handedly transform stream dynamics, preventing the establishment of deep-rooted trees and shrubs. Successful control of reed canary grass requires shading with native competitors as this weed grows poorly in dense vegetation. However, establishing native species in a monoculture of reed canary grass is an arduous task requiring persistent efforts and commitment from local volunteers, government agencies, and others.

 

Identification

Spring

Summer

Late Summer

Winter

  •  emerge a deep green colour

  •  rapidly grows vertically for next 5-7 weeks

  •  colour lightens in summer with tan seed heads
  •  reaches heights of up to 2m
  •  grass begins to brown and die, seeds disperse via wind

 

  •  grass brown and often flattened through flooding

Leaves

Stem

                       Inflorescence

 

 

  •  green with gray hue
  •  spread from stem at right angle, gradually tapering
  •  leaf blades are 9-25cm long, 0.6-1.9 cm wide, flat, and often rough on both surfaces
  •  light green to straw coloured
  •  hairless and hollow
  •  rhizomes are long, scaly and pinkish, spread extensively by creeping runners and rhizomes
  •  flowers and grains grow in dense but branched clusters
  •  turn purplish as plant matures in spring and fade to straw colour in late summer

 

 

Similar Plants

Reed canary grass closely resembles orchard grass (Dactylis glomerata). Reed canary grass leaves are wider, the inflorescence is more narrow and pointed, and the individual flowers have a different shape (see King Country Noxious Control).

 

Key Features

Phalaris arundinacea prefers full sun in moist to wet habitats, growing vigorously in poorly drained areas. It can withstand extended periods of both flood and drought conditions (can be submerged up to 50 days). Reed canary grass dominates native plants and has excessive capabilities to do so when exposed to moderate nitrates from fertilizer run-off in agricultural areas. This grass also has an extraordinary ability to tolerate large quantities of heavy metals and minerals that may be toxic to other plants. Typically, Reed canary grass germinates in early spring and grows vertically for 5-7 weeks, reaching heights of up to 2 meters. Infestations establish quickly and expand rapidly because of dense rhizome growth along with seeds capable of germinating immediately after ripening. These seeds appear in early summer, shattering when ripe and persisting with a seed bank. The native reed canary grass is not thought to be aggressive as its Eurasian counterpart although the two forms are virtually indistinguishable.

 

Control Measures

Many studies have explored possible control methods for P. Arundinacea with few promising results with the exception of using herbicides. Therefore, some believe that control strategies should focus on prevention, slowing further establishment through advocating against the release of new strains. However, several options such as burning, scraping, stomping, spraying and cutting have been used with limited success. Since this grass is prevalent in sensitive wetland areas, an unobtrusive mechanism is desirable. Prescribed fire can kill seeds and possibly rhizomes but burning restrictions for many areas may limit or prevent this method. One recommended strategy is to plant competitive native shrubs and trees amongst reed canary grass with the goal of partially or completely shading this species out. Planting must be accompanied by some type of control and monitoring to prevent reed canary grass from competing with newly planted trees and shrubs.

 

Non Chemical Control

  Hand pulling Stomping Cutting
How Pull out small clumps by hand. To be used is association with planting competitive native plants. Most effective if groups of people walk over or "stomp" down grass. To be used is association with planting competitive native plants. Can be done using a weed eater, scythe, machete, brush saw, and other various hand or power tools. To be used is association with planting competitive native plants.
When Any time of year Necessary to stomp three times in a season (early June, late July, late September) Two stompings are less effective and 1 has virtually no desirable effect Necessary to cut three times in a season  (early June, late July, late September) Two cuts are less effective and 1 cut has virtually no desirable effect
Duration

 

Should continue until planted trees are free growing above reed canary grass Should continue until planted trees are free growing above reed canary grass Should continue until planted trees are free growing above reed canary grass
Pros/Cons Works for small stands, not practicable for large areas This technique is advantageous for control of newly planted restoration sites as trees/shrubs are less likely to sustain damage Can be used with less manpower than other non chemical methods

 

Non Chemical Control

  Shading Burning
How Using shade cloth such as landscape fabric or plastic can slow the growth of grass. To be used is association with planting competitive native plants. Prescribed burning should be directed by certified individuals or groups. Should obtain appropriate burning permits from local authorities
When Cloth should be placed over grass before growth begins in April or May. Late autumn or late spring burning
Duration

 

Cloth may need to be replaced or patched throughout the growing season. Must continue for several growing seasons. May need to be repeated for 5 or 6 years.
Pros/Cons An effective strategy to inhibit growth although expensive and labour intensive. Landscape and plastic rarely last for more than one growing season. Grass tends to grow around, through or push up on the cloth. Is effective when there are other native species present in the seed bank since fire allows native, fire-adapted species to  compete successfully. Not a good method for monocultures reed canary grass where no native seed is present.

 

Chemical Control

 

Spray

How Roundup can be applied in areas without standing water. Do not spray so heavily that herbicide drips off the target species.
When Early spring application when Reed Canary grass is green
Duration The area should be checked after spraying and any surviving grass should be sprayed the following spring
Pros/Cons So far, Rodeo (a form of Roundup - safe for use near waterways) is not approved B.C.

 

Control Warnings:

Disposal - Make sure to properly discard all plant pieces in thick plastic bags and transport them to a sanitary landfill site or incinerator. Composting is not an appropriate means of disposal as this may result in further distribution. Remember that humans can actually spread invasive plants by taking seeds from one place to another on clothing, tires, equipment, etc.

Chemicals - Although some chemicals are approved for control of invasive plants, extreme caution must be taken as many pesticides are harmful to humans. Permits may be required for chemical use and buffer zones exist beside waterways to protect fish and wildlife. Chemical control is not a long-term solution and therefore should be part of a finite plan and applied sparingly. Please see the following web sites for further information: Provincial: MWLAP Pest Information  Federal: Pest Management Regulatory Agency

 

Additional Resources