Integrated Weed Management

Effective weed control in the Shire of Manjimup

The Shire of Manjimup are aiming to improve weed management on private and public land through a series of weed information articles.

Integrated weed management (IWM) is a term used that describes a number of tactics that if all used together can give the most effective control of invasive weeds.

There are economical and productivity benefits for adopting IWM. It includes many simple and cost-effective management changes that could lead to a reduction of herbicides and resistance can be avoided.

IWM examples:

• Map the weed spread and monitor ongoing spread or reduction.
• Use a range of control methods such as spraying, pruning, digging out, burning and mechanical control through the year (as appropriate for the species).
• Understand the seasonal cycles of the weed and undertake control methods at the time that is locally needed to reduce the weed seedbank.
• Concentrate the main effort on the target area, though also consider the edge effect and control the weeds in the adjacent area.
• In dense infestations work from the outside inwards to contain the weed.
• Prevent the introduction of weed seed and propagules from external sources though good hygiene practises.
• Investigate new technologies and techniques to increase efficiencies.
• Consider a weed management plan to schedule the timings and techniques for follow up control.

https://www.agric.wa.gov.au/grains-research-development/crop-weeds-integrated-weed-management-iwm

When managing weeds in bushland areas the Bradley Method can be effective.

https://www.nationaltrust.org.au/services/bushland-management/history/

More information can be found on the Department of Primary Industries and Regional Development website https://www.agric.wa.gov.au/pests-weeds-diseases

Remember to follow chemical manufacturer's safety directions when using herbicides.

Double Gee

(Rumex hypogaeus)

Spray Double Gee before seed is set.

Small infestations and isolated plants of Double Gee can be dug out.

If the plants are seeding, then they should be destroyed by burning them.

An effective control program will aim at killing all plants shortly after emergence and then followed up for several years.

'Prickle rollers' have been developed to gather and remove surface Double Gee fruit from drying greens in vineyards. Cultivation kills seedlings, and can be effective when combined with chemical control.

Wild radish

(Raphanus raphanistrum)

Wild Radish is poisonous in large quantities to mammals.

Hand remove isolated plants several times throughout the year.

Spray before flowering.

A combination of approaches is usually most successful.

Flinders Range Wattle

(Acacia iteaphylla)

Pretty wattle an invasive weed.

Shrub, 2-5 m high, leaves silvery blue-green.

Hand pull seedlings.

Cut and paint mature plants.

Monitor area for new seedlings annually.

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Paterson's Curse

(Echium plantagineum)

Paterson's purple curse germinates in June.

Plants are best treated when young.

Spot spray in winter when most of seed has germinated.

Spraying mature plants when flowers first appear can be successful.

Dig out isolated plants as long as 20 to 40 mm of taproot is removed.

Avoid slashing and mowing as it can cause out of season flowering and extra seed production.

Cape Weed

(Arctotheca calendula)

Cape weed reduces crop yield.

Chip out small infestations, ensuring root is severed well below ground level to prevent re-sprouting from the crown.

For large infestations, spray in early growth stages.

Spear thistle

(Cirsium vulgare)

Prickly thistle can be spread by birds.

Spray seedling and adult plants from rosette stage to early flowering.

Blanket wipers or wick applicators can provide some selective control.

Eliminating seed production is the most effective control technique.

Mowing/slashing at bud or early bloom stage will cause plants to re-sprout.

However, close mowing or cutting twice per season will usually prevent seed production.

Flax Leaf Fleabane

(Erigeron bonariensis)

Fleabane weed is difficult to control with herbicides.

Hand remove small and/or isolated infestations prior to seed set.

Re-sprouts from basal buds after top removal.

Spraying is only effective rosette stage and timing is critical.

Fleabane is very difficult to control with herbicide and can germinate all through year.

Twiggy Mullein

(Verbascum virgatum)

Garden escapee that takes over pastures.

Spray at rosette stage before flowering spike is formed.

Dig out small isolated patches.

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St John's Wort

(Hypericum perforatum)

St John's Wort, beneficial to humans, poisonous to livestock.

Spot spray at flowering (when half are in bud and the remaining half in open flowering.)

Spraying germination following autumn rains can be effective.

Timing of applications is crucial.

Mechanical removal is not advised as plants re-shoot from extensive rhizomes.

Cape Tulip

(Moraea flaccida)

Cattle poisoning symptoms from Cape tulip include loss of appetite and abdominal pain.

Spot spray just on flowering at corm exhaustion.

Dig out small and isolated patches.

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Sydney Golden Wattle

(Acacia longifolia)

Sydney Golden Wattle weed control.

Control techniques include; hand pull seedlings, cut and paint mature plants, applications to trunks of small trees, drill and fill and ringbarking.

Montpellier Broom

(Genista monspessulana)

Broom weed germinates prolifically after fire.

Hand pull or dig out small seedlings ensuring removal of all roots.

For mature plants cut and paint or foliar spray.

Monitor site for recruitment from seedbank.

Pampas Grass

(Cortaderia selloana)

Ornamental grass can clog up waterways.

Dig out small plants and dispose of offsite, as they will reshoot.

Repeated spraying of large clumps will be needed.

Remove flower heads and burn.

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Bridal Creeper

(Asparagus asparagoides)

Spray Bridal Creeper when flowering.

Spray when flowering for best results.

Dig out small patches, removing the large underground tuber.

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Watsonia

(Watsonia meriana var. bulbillifera)

Spray the Watsonia before it flowers.

Spray dense infestations just as flower spikes emerge at corm exhaustion.

Dig out small and isolated patches, remove bulbs and mature flowering spikes with bulbils attached offsite as will reshoot.

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Wild oats

(Avena fatua) and (Avena barbata)

Cut wild oats for hay and silage before the seed it set.

Cut crops or pastures containing wild oats for hay, silage and green manuring before the seed is set.

This can be an effective method for preventing weed seed set providing regrowth is controlled.

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Blackberry

(Rubus anglocandicans)

Blackberry can be sprayed twice a year.

Spray Blackberry from September through to April, potentially twice a year.

Will require follow up for a number of years.

For small infestations or in sensitive areas dig out small plants and seedlings

Cotton Bush

(Gomphocarpus fruticosus)

You can report Cottonbush on the my pest guide app.

Hand pull small plants, remove all root material as possible and bag any seed heads to avoid release of wind-dispersed seed.

Spray before flowering.

Golden Wattle

(Acacia pycnantha)

Commonwealth floral emblem a weed in WA.

Hand pull seedlings, drill and fill and ringbarking are all effective techniques. You may need to take some time in identifying the range wattles on your property to effectively manage them.

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Dune Onion Weed

(Trachyandra divaricata)

Coastal weed needs control to stop spread.

This weed can be controlled at Windy Harbour all year round. Dig out, mow and spray. Remove seed heads and dispose of correctly. Use the right chemical (Chlorosulfuron) as glyphosate alone does not kill the bulb.

Perennial Veldt Grass

(Ehrharta calycina)

Red flowering stems on this weedy grass stands out.

The red flowering stems of this plant stand out from a long distance. Perennial veldt grass is known to be in only a few locations in our Shire, control now will stop it becoming widespread. Dig out plants or spray before flowering, do not slash as it will spread the seeds further.

Dolichos Pea

(Dipogon lignosus)

Pretty weedy pea keeps popping up in reserves.

Dolichos pea is a prolific climber and smothers out all vegetation. This weed is currently being mapped and new populations keep popping up through-out the countryside. Dig out seedlings removing all the roots. Cut and paint the thick vines of larger plants. Spray foliage if possible, this is usually difficult as the plant climbs high.

Victorian Tea Tree

(Leptospermum laevigatum)

Victorian tea tree increases wildfire risk.

Victorian tea tree grows faster and taller than most coastal plants. The plants are also high in oils and can be quite flammable. Hand pull seedlings. Cut and paint mature plants. Large stands can be effectively controlled using a mulching machine. The machine leaves behind the mulch making it harder for seed to germinate.

Red Ink Weed

(Phytolacca octadra)

Ink weed seeds are spread by birds.

Red ink weed is toxic to livestock and humans. Dig out isolated plants and cut root at least 5 cm below ground level. Spray before the plant starts flowering. This plant is smaller than, but looks similar to the declared Pokeweed (Phytolacca americana) that is a new weed in the Shire of Manjimup.

Report Red inkweed if you suspect that it may be Pokeweed to the Department of Primary Industries and Regional Development. Photograph the plant and map it using MyPestGuide™ Reporter (download the app or make an online report).

Creeping Groundsel

(Senecio angulatus)

Creeping grounsel weed can grow easily from cuttings.

Creeping groundsel quickly takes over natural coastal areas. Cut back suckers and stems to limit spread. Be careful with cut-off stems as they will reshoot easily if dropped on ground. Spray when actively growing.

Butterfly Bush

(Polygala myrtifolia)

Common garden plant is invading natural areas.

Butterfly bush is a common garden plant that is invading natural areas. Once established it is difficult to control as seedlings germinate on mass. Any control will need to be followed up for a number of years. Hand pull seedlings. Cut and paint mature plants.

African Lovegrass

(Eragrostis curvula)

African lovegrass is becoming resistant to herbicides.

Many areas that contain the problematic African lovegrass are sprayed and mowed in efforts to control it. All weeds will become resistant to herbicides over time and a number of alternative control methods should be used to prevent it. Scheduling mowing at three week intervals will stop seed set, spot spraying in between mowing times. Ensure machines are clean before moving to unaffected areas. Dig out isolated plants before they become next year’s problem.

Black Flag

(Ferraria cripsa)

New weed in Shire of Manjimup spreads quickly.

Black flag has been recorded in the Shire of Manjimup for the first time. This new weed spreads quickly and is a garden escapee. New corms are produced each year. Dig out and dispose of correctly. Spray just prior to flowering.

Stinkweed

(Dittrichia graveolens)

Summer weed is sticky and smelly.

Stinkweed is easy to identify from the sticky feel and strong menthol smell. Use gloves when hand pulling to avoid the sticky resin. Hand remove isolated plants before flowering. In paddocks where it is thick, slash close to ground before flowering as the flowers have already formed seed.