Please click on a letter to list all weeds in archive beginning with that letter.

Olea europea
Olives
Onion grass
Onion weed
Opuntia spp.
Orange hawkweed
Orobanche minor
Oxalis spp.
Ox tongue thistle

Olea europea - Olives
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Date: Mon, 30 May 2005
From: Katrina Roberg <KatrinaRo@hume.vic.gov.au>

A Sulphur Crested Cockatoo was spotted eating olives from a tree in Sunbury last week. We at Hume Council, North West of Melbourne are keen to hear from others who have witnessed parrots, specifically Cockatoos or Corellas, feasting on and dispersing olives. Please let me know if you have witnessed this.

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Date: Mon, 30 May 2005
From: Ronald Tuckwell <civilwords@bigpond.com>

I cannot vouch for parrots, but, when I was living in Kapunda in South Australia, I was constantly removing seedlings of olives, boxthorn and cotoneaster from around the bases of fence posts, having clearly been dropped there by birds. There were trees of all three species within a half kilometre radius.

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Date: Mon, 05 Jan 2004
From: Sandy Lloyd <slloydagric.wa.gov.au>

There was a huge article on weeds in The Australian on the weekend, too long to post here, there's also an article on feral olives in today's Oz

Blots on the landscape
By Asa Wahlquist
January 03, 2004

English broom, topped lavender, hawthorn, pink periwinkle and gladioli - the names have the ring of an English country garden, but in Australia they are delivering a green death. These plants have escaped the garden to become weeds in Australia, joining a cohort of more than 2800 species of plants that are strangling and displacing native plants, starving wildlife, destroying ecosystems, poisoning stock, choking waterways and causing acute respiratory distress and allergies in people.

The annual cost of weeds to agriculture alone is more than $4 billion. Add the cost to the natural environment through loss of plant, animal and insect biodiversity, as well as the effect on human health, and the figure soars to many times the cost of salinity. Indeed, Australian Weed Management Cooperative Research Centre chief executive Rachel McFadyen argues that weeds pose a far greater threat to the Australian environment than salinity...

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Date: Tue, 06 Jan 2004
From: Richard Denver<richardweedmanager.net>

Government bodies are always going to complain about not having enough money to solve the weed problem. Perhaps they are expecting too much to quick. If you were to go to a gym one would not expect to become slim in a matter of days. It takes time and it takes a good method to get results. Controlling weeds is a lot like getting fit without spending time on the following list below you would never get results....................

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Date: Tue, 06 Jan 2004
From: Sandy Lloyd<slloydagric.wa.gov.au>

Just found the olive article from yesterday's The Australian

Chain gangs pitted against feral olives
By Rebecca DiGirolamo
January 05, 2004

Prisoners are attacking them with chainsaws, conservationists want to ban them and the Rann Government is burning hectares of them. Thousands of feral olive trees infest 75 per cent of native bushland in the Adelaide Hills and all stops are out to eradicate the trees, which pose a huge fire risk as temperatures begin to soar.

Over the past three years, chain gangs of low-security prisoners have been hacking into feral olive trees five days a week across South Australian national parks and reserves.

The program has removed "thousands and thousands of trees" while providing prisoners to be released into the community with horticultural qualifications, said Adelaide Pre-Release Centre acting general manager Vic Locke.

"They go through and take out all the olive and non-native trees from these areas and clear tracks," he said.

District park ranger Terry Gregory, who is in charge of 17 major national parks south of Adelaide, said the prisoners were among a small army of hundreds of volunteers, contractors and researchers fighting against the weed's invasion of Australia.

He said South Australia had a strategic management plan to target dense olive infestations threatening endangered native flora and fauna and encroaching upon homes.

"You can't ignore it any more," Mr Gregory said.

"If you ignore it, you do so at your own peril."

Researchers from Flinders University have produced "weed maps" charting 53 sq km of metropolitan Adelaide prone to feral olives. The maps have found 2.3 sq km of feral trees requiring removal at a cost of about $3.4 million.

"Feral olives have taken over much of the Adelaide Hills - they are threatening bushland and they're in massive thickets in some areas," said Graham Churchett, president of the Friends of Black Hill and Morialta.

The group has been eradicating olive trees in the area for the past 18 years and wants to ban new olive groves.

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Date: Fri, 20 Sep 2002
From: Renee Wierzbicki <Renee.Wierzbickirbg.vic.gov.au>

Does anyone know if Olive cultivars (Olea europea) are weedy? In particular I'm looking at the cultivars Manzanillo, Verdale, Sevilliano and Kalamata. None of these varieties are propagated by seed for the trade.

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Date: Mon, 23 Sep 2002
From: David Cooke <Cooke.Davidsaugov.sa.gov.au>

Yes, they sure are weedy: the feral olives (Olea europaea subsp. europaea) invading native vegetation in South Australia are the F1 (and later generation) offspring of cultivars bred for oil production and table olives.

Olives were first introduced to South Australia in 1836; five selected cultivars from Marseilles were imported by the South Australian Company in 1844, and later from Portugal, Spain, Provence and northern Italy. Because climate and soils in parts of SA resemble these areas, they readily become naturalised. The feral olives in SA are regarded as a source of valuable germplasm by plant breeders at Adelaide University, who have been able to trace their connection with old cultivars. [Mekuria, G.T., Collins, G. & Sedgley, M. (2002) Genetic diversity within an isolated olive (Olea europaea L.) population in relation to feral spread. Scientia Horticulturae 94: 91-105.] The ferals may include trees with desirable recombinations of characters from these cultivars. I think the cultivars Manzanillo and Kalamata are involved - the authors of this paper may be able to give you more info on this.

Compared to other tree crops, not much selective breeding has been done on olives. The cultivars seem to be heterozygous clones selected from spontaneous, uncontrolled crosses or at most a few generations removed from wild forms. The cultivars can be competitively equal to the original wild forms: In southern Europe and the Levant, ferals and crosses with cultivars have largely replaced the original wild O. europaea strains [Lumaret, R. & Ouazzani, N. (2001) Ancient wild olives in Mediterranean forests. Nature 413: 700]

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Date: Wed, 25 Sep 2002
From: Neville Crossman <neville.crossmanflinders.edu.au>

I'm attempting to compile a list of locations outside South Australia where olive (Olea europaea) has naturalised. I would be grateful if those of you who have observed or controlled 'feral' O. europaea anywhere outside of SA inform me of, via return email:

1) the location (country, if outside Australia, State, nearest town),

2) approximate extent (few isolated individuals, many individuals, large population, serious infestation), and

3) if possible, whether the olives were European (ssp europaea) or African (ssp cuspidata or africana).

Opuntia sp - Prickly pear
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Date: Tue, 20 Mar 2007
From: Armin Korschan <akorscha@bigpond.net.au>

Just thought I throw a question in relation to Prickly Pear at you – not sure which one it is - but found the first outbreak near Pakenham Vic, less than 100 individuals, situated within weedy grasses near a stream.  Would appreciate any success stories, please.

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Date: Wed, 21 Mar 2007
From: Roy.Lovel@csiro.au

You'll probably here from others but we have been battling prickly pear and its cousin wheel cactus around Baringhup for the past 10 years and am pleased to report that we are winning.

While many methods have been trialled the preferred control method is a 4 ml injection of round up (50% dilution with water) into the top of each "arm" of the cactus. It takes a while before showing signs of effect so be patient

I strongly recommend getting on top of the problem, the images of mountains covered by cactus are real and it is surprising how quickly it can get away.

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Date: Thu, 22 Mar 2007
From: Alexandra Shackleton <ashackleton@geelongcity.vic.gov.au>

I've had success simply digging them out - ensuring all the bits are bagged and disposed of (usually deep tip burial), and have also used a "wound-and-paint" variation for really big ones. As cutting through them sometimes isn't an option, making multiple wounds with a saw/tomahawk etc and painting with Roundup seems to work. Wounds to the base of the stems work the best. It won't kill the whole plant, but will kill off sections of it, enabling further treatment the following year. Just make sure that any bits that fall off get cleaned up otherwise they'll sprout too!

Stem injection with Roundup also works - just depends on equipment and skill set for applicators really.

Be aware that there's about the same amount of biomass under the ground as above it, so digging out can leave massive disturbance sites. If you're able to rehabilitate an area, you may like to even consider a small excavator or Dingo - saves on prickles - just watch the tyres.

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Date: Tue, 02 Mar 2004
From: Sandy Lloyd <slloydagric.wa.gov.au>

http://www.smh.com.au/articles/2004/02/29/1077989433308.html
Spiky pest is back, but now there's no chance it will go pear-shaped
By Malcolm Brown
March 1, 2004

The most unlikely of Australia's imports, the prickly pear, which ruined millions of hectares of farmland and provoked special laws bidding its destruction - is making a comeback. The plant has lovely tasting fruit, for those prepared to brave the prickles, and is being farmed in parts of south-west Sydney. There is no danger of the plant spreading, the growers say, because the bug introduced in 1926 to control the prickly pear, the cactoblastis caterpillar, is still around and ready to swoop...

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Date: Tue, 02 Mar 2004
From: Stan Kailis <skailisagric.uwa.edu.au>

Several years ago I posted a note about prickly pear growing in Sicily and its possible potential as a fruit crop.

My suggestion was not popular with the group because of the weed potential of prickly pear.

On a plane yesterday coming back to Perth from the Hunter Valley, I read on the front page of one of the Sydney papers regarding the commercial value of prickly pears - a large colour photo etc.

The article also referred to insect control of this species indicating at least in NSW the specific insect is still active.

My questions are:
1. Is this correct?
2. Is it true for all of Australia?
3. How effective is the control?
4. What advice is available for growers if they wish to sell prickly pear fruit?

I add that I work with olives and this species has a degree of weediness especially in South Australia.

I have also worked on tea species eg Camellia sinensis and this is reported to have weed potential.

I have a PhD student working on Wild Radish which is a weed so I am concerned about weeds

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Date: Tue, 02 Mar 2004
From: Roy Lovel <Roy.Lovelcsiro.au>

It's amazing how often those with a commercial interest become the "expert" and how there advice seems to promote the commercial activity.

Broad control outside of ones own properties is part of the beauty of biological control and we would love to have an effective biological agent. I'm not a great a botanist but they tell me the majority of the cactus problem in Central Victoria is "wheel cactus" and that it has not been possible to establish cactoblastis on wheel cactus in our areas. Recently a virus (?) was released onto patches of both prickly pear and wheel cactus and we are waiting to see the results.

I'd love to hear about any other control mechanisms that people have had success with.

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Date: Tue, 02 Mar 2004
From: Tony Rodd <tonyroddisp.net.au>

There seems to be a degree of confusion among those posting on this subject.

The prickly pear in the article in Monday's Sydney Morning Herald is Opuntia ficus-indica, the "Indian fig", cultivated for its fruit in Europe and western Asia for hundreds of years. It has been cultivated in Australia almost since the beginning of white settlement and so has had ample opportunity to become naturalised, but in fact has not done so to any significant extent. Its fruit crop is of some importance commercially.

Mann (1970) Cacti naturalised in Australia and their control (Dept of Lands, Qld) devotes many pages to the weedy opuntias but mentions O. ficus-indica only briefly under 'Less important species'. He noted "It occurs in many gardens throughout Queensland and occasionally as an escapee. In New South Wales it grows in several localities."

The 'wheel cactus' that has become a threat in Victoria is Opuntia robusta, whereas in New South Wales and southern Queensland the worst weed species seem to be O. stricta (common pest pear), O. aurantiaca (tiger pear), O. tomentosa (velvet tree pear) and Cylindropuntia imbricata (devil's-rope pear).

In New South Wales O. ficus-indica is specifically exempt from the blanket classification of all Opuntia spp. as W4f noxious weeds. See http://www.agric.nsw.gov.au/noxweed/. Here is the wording for one 'control area' under the legislation, but it is much the same for all of NSW:

Prickly pears (Opuntia spp.) is declared noxious in the Hawkesbury River County Council control area (including Baulkham Hills, Blacktown, Hawkesbury and Penrith council areas). Indian fig (Opuntia ficus indica) is exempt from declaration

The weed control category is W4f. This means that: The weed must not be sold, propagated or knowingly distributed. Any biological control or other control program directed by the local control authority must be implemented.

In Victoria, as far as I can gather (see http://www.weeds.org.au/docs/weednet6.pdf) the only opuntias proclaimed as noxious are O. monacantha (P3), O. robusta (P3 C2) and O. stricta (P3 C3).

Don't know what the current situation is in Queensland. The last I knew, all opuntias were prohibited.

In answer to Stan's question, yes, Cactoblastus is still active though my impression is that O. stricta is its main host species. O. stricta is very common on the coast and ranges of NSW and a good proportion of plants I see have the cactoblastus larvae in them, but more often than not it fails to kill the plant, only weakening it. I have not seen it affecting O. aurantiaca which is a particularly nasty weed in the Hunter region and parts of the Hawkesbury valley. I do not know how big a problem cactoblastus is for commercial growers of O. ficus-indica. No doubt the grower featured in the Herald article could tell you. He is Vic Marando, of Leppington, and the article says he has 'up to 3000 plants over more than 2 hectares'. It does say, in fact, that the crop has to be sprayed 'at least four times a year to protect it from the bugs.' The writer of the article appeared to be blissfully unaware that there is more than one kind of 'prickly pear'.

I think the Opuntia shown in the Good Weekend article cited was also O. ficus-indica.

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Date: Tue, 02 Mar 2004
From: Philip Maher <Philip.Mahernrm.qld.gov.au>

All species of Prickly pear (Opuntia spp.) are declared as Class 2 Plants under the Land Protection (Pest & Stock Route Management) Act 2002 with the exception of the Indian fig (Opuntia ficus-indica) which is exempt from declaration in Queensland. Under the Land Protection (Pest & Stock Route Management) Act 2002 landholders must take reasonable steps to keep land free of Class 2 plants, a person must not take a plant that is a class 2 pest, or a part of the plant for commercial use, they must not supply a declared pest, they must not supply things containing reproductive material of particular declared pest plants other than under a pest plant permit.

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Date: Tue, 02 Mar 2004
From: Ian Faithfull <Ian.Faithfulldpi.vic.gov.au>

Unfortunately the Sydney Morning Herald article is a confused piece which fails to recognise that "prickly pear" is an imprecise generic term for some of the large Opuntia species. The prickly pear grown commercially is O. ficus-indica Indian Fig. The main pest species in Australia was O. stricta, common or erect prickly pear, but several other species are notable weeds. A further set of Opuntia spp., not, or arguably classed as 'prickly pears', are weedy in parts of Australia (eg. O. aurantiaca, tiger pear in Victoria).

There are hundreds of small plantations of Indian fig in yards, gardens and farms in Vic, particularly gardens of southern European immigrants. There are several cultivars with different flesh colours and other characteristics. There are spiny and spineless types. There is said to be one main commercial Indian fig grower in Vic, Joe and Meredith Lizio at Glenrowan in the NE, who have "arguably Australia's largest commercial cactus farm" with 10 ha in production (Weekly Telegraph, Wangaratta 16 March 2000, North East and Goulburn Murray Farmer March 2000). A short detour off the Hume Freeway will enable you to see the plantation. I suspect there are also commercial growers in the Mildura area.

The Lizios were reported to have a run a five year campaign to push the sale of fruit into supermarket chains, to have developed their own cultivars and to have made a lotion (with teatree oil) from the cladodes. It was also reported that they were recognised by state government as commercial growers, and that "This recognition is essential to protect the crop from the potentially harmful release of insect control methods used to combat the spread of the prickly pear species declared as a noxious weed".

What that means is not clear, but probably it acknowledges that deliberate biological control agent releases by government will not be made in the area - see discussion below. I don't know whether any pest insect control is required to maintain the orchard.

I bought prickly pear fruit at Victoria Market (Melbourne) in the early 1980s and see it occasionally in supermarkets in Melbourne, although the period of availability is short and sales don't appear to be brisk.

The Cactoblastis cactorum moth which destroyed (alone or with assistance of other organisms) the massive prickly pear populations in Queensland and northern New South Wales during the late 1920 and 1930s and has kept the worst prickly pear species under control there ever since, has in the past not been considered to be able to survive in Victoria. Southern Australia has generally been thought to be too cold for populations to persist and the insect was considered to be ineffective south of 32 degrees S (a line roughly through Taree, Dubbo and Broken Hill, NSW and Hawker, SA) (F.Wilson, A Review of the Biological Control of Insects and Weeds in Australia and New Guinea, CAB, 1960). A population was established at Eldorado in north east Victoria in 1956 and 1957 on O. stricta but survived for less than 2 years, and has not been noted there subsequently (Parsons, Noxious Weeds of Vic, 1973).

However larvae were found at Merbein South, near Mildura, infesting a weedy population of Indian fig by Geoff Tyers of DPI in 2000. In mid 2001 a population was found at Keilor, just W of Melbourne on the Maribyrnong River by Jason Summers, Brimbank City Council's Parks Conservation Officer, with the host plant probably O. stricta. It is not clear whether these finds are isolated outbreaks resulting from permanent low level populations or deliberate or accidental introductions of infested cactus, or whether climate change or adaptation by the moth now enables it to better survive in Victoria, or whether the insect is illegally introduced and is a different biotype or species than the one in Qld and N NSW, which, according to Rachel McFadyen, [in lit. 2001] virtually never attacks Indian fig.

Julien & Griffiths (Biological Control of Weeds. A World Catalogue of Agents and Their Target Weeds, 4th Ed. 1998) do list O. ficus-indica as a deliberate cactoblastis target in Hawaii and South Africa (pp.39-40) and as having spread into and attacked ficus-indica in Puerto Rico and the US Virgin Islands after releases in other countries (pp. 138-139).

A number of deliberately introduced cochineal insects, Dactytopius spp., are significant agents in controlling Opuntia spp. in Australia, particularly so in Vic where cactoblastis has not worked. Each species has favoured hosts, with species generally feeding on, or being effective against one or a few of Opuntia species. D. opuntiae, released on O. stricta in Victoria, provides control of O. ficus-indica in Hawaii and S. Africa according to Julien & Griffiths. It has host-specific biotypes (Githure et al. African Entomology 7(1), 43-48): the 'stricta' biotype, effective in Australia against O. stricta, and the 'ficus' biotype associated with tree-like cacti including ficus-indica. However it is not always clear which Dactylopius sp. or biotype one is dealing with. I found that an undetermined Dactylopius sp. (probably D. opuntiae'stricta' biotype) on an O. stricta plant from an infestation at Eldorado NE Vic failed to significantly damage O. ficus-indica kept in a pot beside it for some years.

Indian fig is considered naturalised in Victoria, and usually establishes close to plantations or from dumped material (Stajsic & Carr, Flora of Vic 3, p.128), but infestations are small. It is not clear to what extent the prickly pear biocontrol agents present in Victoria are preventing it from becoming a more problematic pest, so it is uncertain whether more widespread cultivation of it would lead to it being an increased weed problem. The cochineal insects disperse slowly and only over short distances. For biocontrol purposes they need to be redistributed manually. They are unlikely to infest an Indian fig orchard that has no prickly pear infestations near it, and even less likely to find their way to small and isolated populations of the plant. Moreover, it is probable that the 'ficus' biotype may not be present in much of the State, if it is present at all. Cactoblastis could conceivably fly in from a much greater distance, but there are few reports of its presence in this State, where, despite global warming, it is probably still restricted by climatic factors. Indian fig growers certainly need to ensure they dispose of unwanted plant material safely and that the fruit are not left to the birds.

No biological control agents appear to have been released anywhere in the world for Opuntia robusta wheel cactus (see Julien & Griffiths), and the research needed to identify potential agents has not been done. I've heard nothing about the "virus (?)" supposedly released on this species that Roy Lovel mentions. To be effective, a plant virus generally requires a vector, which presumably would be an insect that feeds on the plant. Maybe Roy has confused it with the cochineal which has been released recently for control of O. aurantiaca in Vic.?

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Date: Tue, 02 Mar 2004
From: Sandy Lloyd <slloyd@agric.wa.gov.au>

Current cactus declarations for WA fyi - In very basic terms, P1 is can't import, can't cultivate, transport, sell etc.
P2 - must be eradicated
P3 - infestations must be made smaller
P4 - infestations must not get bigger
see declared plant list for more detail:
http://www.agric.wa.gov.au/

Harrisia cactus (Eriocereus martinii);
P1, P2; for the municipal districts of Port Hedland, East Pilbara, Roebourne
and Ashburton.

Prickly pear (Opuntia spp.);
P1; for all municipal districts in that portion of the State North of
the 26th parallel of latitude.
P2; for all municipal districts in that portion of the State North of
the 26th parallel of latitude except for the municipal districts of Exmouth,
Carnarvon, Murchison, Upper Gascoyne and Shark Bay.
P4; for the municipal districts of Exmouth, Carnarvon, Murchison, Upper
Gascoyne and Shark Bay.

Oxalis Sp.
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Date: Tue, 06 Jun 2006
From: Vivien & Charlie Clarke <clarke@nex.net.au>

Has anyone had any success in getting rid of oxalis. I have been employing two methods.  Digging up the corms (carefully so I do not spread the corms into another area) and painting the plants with straight roundup from time to time. However they still look as vigorous as ever.  Has anyone used another method and had success.

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Date: Tue, 06 Jun 2006
From: Don Matthews <don@heathdon.com.au>

Where are they growing, in what situation ??? Brushoff / Ally is  effective when used as directed , ie crops / pastures

More info please.

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Date: Tue, 06 Jun 2006
From: Randall, Rod <RPRandall@agric.wa.gov.au>

Physical removal of Oxalis is never recommended. No matter how careful you are you will leave small corms behind and if the Oxalis species in question is Oxalis pes-caprae then these plants are particularly adapated to benefit from attempts at physical removal. The Biology of Australian Weeds Vol 2 series by John Pierce, over 15 pages, documents the biology, management and control of this Oxalis, the most widespread and weedy Oxalis in Australia.

If you have to deal with this species it is highly recommended you obtain a copy of this Volume, most easily from the publishers RG and FJ Richardson. Their web site is http://www.weedinfo.com.au/ for $65 + PP. The volume also covers 15 other significant Australian weeds. I can assure you what you will learn from that article will be worth many time more than the cost of the book and will save you a lot of time and effort.

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Date: Tue, 6 Jun 2006
From: Greg Boyles <gregsplants@eftel.net.au>

Unless you wanted to try spraying them with metasulfuron methyl (Esteem/Brushoff) for a while I would suggest you just scrape up as much of the top soil as possible (if it is a smallish area) and dispose of it in landfill. You can then more easily dig out any re-sprouts.

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Date: Tue, 6 Jun 2006
From: Greg Boyles <gregsplants@eftel.net.au>

That's why I specified 'small area' such as a garden. It is quite manageable to remove oxalis physically in that case, with plenty of follow-up of course.

The bush crew company I am with have found that Esteem works quite well on weeds with bulbs or rhizomes etc. Again you still have to have a few goes at the weed but metasufuron methyl reaches the bulbs more effectively than the other broadleaf herbicides. We use a lower concentration, particularly if spraying around native shrubs etc.

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Date: Tue, 06 Jun 2006
From: Ian Higgins <ian.higgins@nccma.vic.gov.au>

I presume you are talking about Soursob (Oxalis pes-caprae)?  If so, I recommend mulching with reinforced concrete!

Seriously, I have had success with herbicides but any kind of soil disturbance just seems to make it worse.  One spray of glyphosate (eg, RoundUp) based herbicide at the right stage of growth can kill most (but definitely not all) of a vigorous infestation, but I found that it had remarkably poor success with non-vigorous plants.  These days I use a mixture of glyphosate and metsulfuron methyl.  I still go by a Darcy Duggan recommendation that the right stage (bulb exhaustion) is more or less when the flower buds are just about to open.

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Date: Tue, 06 Jun 2006
From: Michael Neighbour <michael@australianecosystems.com.au>

I have found that glyphosate during the flowering period is very effective. Brushoff is probably as effective... if you are wanting to rotate your treatments from year to year too.

Orobanche minor - Broomrape
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Date: Wed, 29 Nov 2006
From: Tim Connell <Tim.Connell@whittlesea.vic.gov.au>

This spring we found a discrete infestation of Lesser Broomrape (Orobanche minor) at a reserve in Sth Morang, Victoria on Melbourne's northern fringes growing in with Patterson's curse and Themeda triandra, (parasitizing on one of the two?). Being grateful that the plant wasn't Branched Broomrape (Orobanche ramosa) we carefully hand weeded, removing as much bulbous material as possible with minimum disturbance to areas of native grasses. Disturbed areas where then thatched with Kangaroo grass seed collected from last year.

This plant is a new one for us in this reserve and appears to have come up on an old dirt bike track (most likely vector). We would like to monitor the site and continue control of smaller emergent plants, anticipating many more as most of the adult plants had gone to seed when removed.

Does anyone know of an efficient way of controlling this or similar species that does not involve soil disturbance?

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Date: Wed, 29 Nov 2006
From: "Randall, Rod" <RPRandall@agric.wa.gov.au>

Orobanche minor is widely naturalised across southern Australia and is certainly naturalised around Melbourne. Its extremely common parasite on nasturtiums, just loves em.

The seed are tiny, measured in micrometers and will disperse on your shoes, clothes, animals will carry them around as will water and wind.

To be honest I wouldn't waste my time trying to control this species. It rarely makes an obvious impact, I've seen patches of nasturtiums looking pretty sick at times and clover pastures can sometimes be affected but its nothing like as virulent as branched broomrape.

Its seed can remain dormant for years, even decades, and effective control  measures have really not been found although work continues on branched broomrape and the most promising work is in breaking seed dormancy, not something that would help a great deal in bushland situations unless you were prepared to kill the hosts...

I'd save my efforts for more rewarding work.

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Date: Wed, 29 Nov 2006
From: "Virtue, John (DWLBC)" <Virtue.John@saugov.sa.gov.au>

Broomrapes are parasites of broadleaved plants, so kangaroo grass would definitely not have been a host. Were there clovers at the reserve? - as Orobanche minor commonly grows on Trifolium species, but other legumes, daisies and other dicot families can be hosts. Removal of bulb material is not critical as it is an annual and does not actually have a bulb - rather it is a tubercle which stores nutrients to enable a flowering shoot to emerge out of the ground. As Rod said it is not perceived to be a high impact species, with limited agricultural or environmental impacts, unlike its cousin Orobanche ramosa which hosts on a wide range of agricultural and horticultural crops and native herbs.

In terms of control, Group B herbicides such as metsulfuron methyl or chlorsulfuron applied to hosts in late winter/early spring are effective at preventing emergence. Sub-lethal rates of glyphosate applied to hosts can also give selective kill as the herbicide is concentrated in the parasite.

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Date: Thu, 06 Nov 2003
From: Andrew Coughlan <coughlanispdr.net.au>

I've recently encountered a population of Orobanche minor on the banks of Botany Bay, south of Sydney New South Wales. The area is soon to be reshaped for salt marsh enhancement on the margins of a mangrove community. The main host of this parasitic plant, Vicia spp., has been sprayed, but seed set appears inevitable. A secondary host is Catsear - Hypochoeris sp.

My main questions are:

1. Is there a best practice approach for containing material (ie. soil and other 'fill') prior to safe disposal?

2. Would a practice like 'firing' reduce the vigour of maturing seed heads, or, would manual collection of a relatively small population achieve a 'safe' result?

Information searches have shown that this plant is a potential nightmare in a careless urban environment and even the most careful rural environment.

This plant is not noxious here, but its abilities are particularly scary.

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Date: Fri, 07 Nov 2003
From: Jackie Miles <jmilesacr.net.au>

In response to Andrew Coughlan's query about broomrape, Orobanche minor, I have seen this plant pop up a couple of times where I live on the NSW far south coast, and disappear, never to be seen again. I know branched broomrape is the subject of much excitement where it has been found in SA, but O. minor seems pretty innocuous to me. However, I would be wary of claiming that this is always the case. It may be more aggressive in different circumstances.

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Date: Fri, 28 Nov 2003
From: Andrew Coughlan <coughlanispdr.net.au>

Thanks for your insights. Any information is good information!

I have done a search for other populations without success. The area in question has a long history of dumping. It is adjacent to a 'light industrial' development. The soil is a light sandy loam but is enhanced by the vicinity of compulsory "garden projects". Toyota is one of the neighbours and are not ashamed about fertiliser use. All developments along the area are required to do environmental enhancement. A recent "complier" planted dwarf Lilli Pillis and a weedy Pennisetum (setaceum) around a remnant Casuarina Endangered Plant Communty.

I am aware of the efforts of both SA and WA in acknowledging Branched Broomrape and am sorry to hear that funding is so tight. I downloaded the fact sheet from the website of WA Agriculture and used some of the info to promote reporting from Bushcare volunteers (with acknowledgement).

I question the information on inundation. At least one population exists on the margins of a saltmarsh, bordering mangroves, that has been observe under water within the last month. This water is saline yet the population persists.

Information from other colleagues suggests that all of the locations where this plant is found in my area will be under water in extreme conditions.

I look forward to further discussion

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Date: Mon, 01 Dec 2003
From: Andrew Coughlan <coughlanispdr.net.au>

Hope you don't mind, I will 'post' this for others to see.

Other respondents have also suggested that the Orobanche spp. is benign, but I do not trust anything with huge seed potential and subject to spread by human activity.

This genus of plants? (behaves more like a fungi) is on the AQIS prohibited list. I see no reason to do anything but eliminate on suspicion. Before you all jump to conclusions, I'm much more accepting of people entering this country.

Subject still open for discussion.

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Date: Mon, 01 Dec 2003
From: Rod Randall <RPRandallagric.wa.gov.au>

A "benign Orobanche species" is almost an oxymoron....

They are obligate root parasites and as such some plant species somewhere is losing water and nutrients to these plants. There is however a native Orobanche species and it is likely to have more impact on natives than an introduced Orobanche, seeing it has evolved to parasitise our local flora.

Orobanche cernua, with a number of sub taxa, is native here and obviously would be capable of parasitising some of our native flora, but I've never seen it so I can't comment on what it parasitises.

Orobanche minor is native to Europe, western Asia and North Africa and can parasitise a wide range of plants commonly found in our gardens, they just love nasturtions, as well as many of our common pasture species.

Other Orobanche species such as O. ramosa can be devastating to many horticultural crops making it impossible to grow certain crops such as carrots or tomatoes in many places overseas. Many countries consider the genus as quarantine pests further complicating matters when it comes to export markets.

No, I'd not describe them as benign.