2019 EditionGamba NewsTis the seasonIdentifying gamba and planning for good gamba managementAfter a scorching hot build-up it’s been nice to hear the rumble of thunder in approaching storm fronts, with a few showers to cool things down nicely. The rain will also help to green up a landscape crisped dry by hot desert winds. Everything grows in the wet season and unfortunately this includes that scourge of the savannah, gamba grass. Like the vast majority of weeds, control of gamba grass is best carried out while it is in its active growth phase and the onset of the wet is truly the season to get busy! With a surge in new growth all around it can be easy to confuse friend with foe. Gamba grass is a Weed of National Significance in Australia and a declared weed in the Northern Territory. Everyone has a role to play in the management of declared weeds and in the case of gamba grass, your responsibilities differ depending on where you live. The majority of the Top End is in the eradication zone. All public and private landholders in this area must work towards eradicating gamba grass from their property, prioritising outlying plants and new infestations. Owners and occupiers of properties in the more northerly management zone are required to actively manage and contain the gamba grass on their patch. This means reducing the size and density of infestations, constructing buffer zones and fire breaks and ensuring that gamba grass does not spread into clean areas, road corridors or adjoining properties. Wherever your property might be it is particularly important that you ensure that you practise good farm bio security. Protect your most important investment by stopping gamba grass plants from seeding wherever possible and by keeping machinery and other vehicles clean and free of weed seed. The wet season is a critical time to prevent gamba growth and spread. Spraying is most efficient and effective when the lush green leaves are between knee and waist height so the time for gamba planning is now! Head to the gamba grass webpage at nt.gov.au for all you need to know about planning for a successful weed management season including those all-important gamba grass declaration zones. Free help to control gamba – Gamba Action ProgramAssistance to manage your gamba is available through the Gamba Action Program (GAP). You can get free herbicide, spray equipment loans and weed management advice to help control gamba in the Top End, including Katherine. The Gamba Action Program is open from 2 December 2019 to the end of April 2020, or until herbicide runs out. The herbicide provided through the program is called glyphosate. Glyphosate is the recommended herbicide for use on weedy grasses, including gamba. You can apply for 1L, 5L or 10L of the herbicide, depending on the size of your gamba infestation. For more information on the Gamba Action Program, legal requirements for land managers, or for general advice on gamba control, visit nt.gov.au or phone the Weed Management Branch on (08) 8999 4567. Gamba compliance updateYou may have spotted the Gamba Action Vehicle getting around the rural areas of Darwin over the recent weeks. With the arrival of the rain and gamba springing back to life, the Weed Management Branch is in full swing doing roadside inspections of properties for unmanaged gamba in the Top End. These inspections are targeted in areas where gamba density poses the greatest risk, and are conducted as part of the compliance component of the Gamba Action Program. Almost 1300 roadside inspections have been undertaken and officers have started making contact with landholders to offer advice and instructions. Land managers may be issued with an order to control or eradicate gamba. Penalties can apply for failing to comply with an order. Last year we were very pleased to see the majority of land managers do the right thing. It’s Time to Take ActionWeed Emergency Response NewsSiam weed infestation detected in the Northern Territory for the first timeNative to the Americas, Siam weed has become a major land management issue across tropical areas of Asia and Africa. In 1994 it was detected in the Tully area of Far North Queensland and until recently was confined to that region. An incursion of Siam weed has recently been detected on three properties in the greater Darwin region. Siam weed has high nitrate levels and in some countries has led to cattle deaths and abortions when stock have been accidentally fed contaminated fodder. Its rapid rate of growth means that it has the potential to outcompete crops, pastures and native vegetation. In addition to this, Siam weed may cause skin complaints and asthma in allergy prone people. These potential environmental, economic and health impacts, when combined with the costs associated with its control mean that it is considered one of the world’s worst weeds. The Weed Management Branch has notified the National Biosecurity Committee of this most recent incursion of Siam weed. We are working closely with the landholders and other government departments to contain and control the current known infestation and conducting surveys to determine how far it may have spread. As with any weed management, the early reporting of a suspected Siam weed infestation is essential to successful control and eradication efforts. Siam weed can look similar to other weed species but there are a few outstanding features that help in identification. The pungent smelling leaves of this scrambling climber are soft, green, hairy and roughly triangular in shape. They also have a very distinctive three-vein ‘pitchfork’ pattern running the length of each leaf. Pale pink-mauve tubular flowers are held in clusters at the end of the branches. The flowers can appear white if seen from a distance but will usually turn darker lilac when mature. Siam weed flowering is triggered in mid-year by shorter day lengths and they produce enormous numbers of seeds within 8-10 weeks after flowering. Each seed has a tuft of white or brown hairs that act as a little parachute, allowing it to be easily transported by wind or water. Preventing weed spread through biosecurity measures is as important to Siam weed management as early detection. The hairs on the seed help it attach to vehicles, clothing, footwear and animal fur. It is very important that travel through known areas of infestation is controlled and that vehicles, machinery and any personal gear used in an infested area be cleaned thoroughly before leaving an infested area. Let’s work together to stop the spread of Siam weed. If you have seen Siam weed, or think you may have it on your property please contact the Weed Management Branch on (08) 8999 4567 or at weedinfo@nt.gov.au Early weed detection is the keyEmergency responses for parthenium weed and rubber vineGlobally the number of accidental weed introductions continues to rise alongside the increase in development and the movement of people and vehicles in and out of natural areas. When it comes to weed management, early detection, strategic planning and swift action can mean the difference between expensive ongoing management and a successful eradication program. The Weed Management Branch uses an Incident Action Plan (IAP) decision making framework to ensure that the response to new high priority weeds is planned swiftly and effectively. Parthenium weed costs Queensland producers more than $22 million annually in reduced production and increased management costs. In October 2018 a new incursion of parthenium weed was detected in the Katherine region. An IAP has assisted the landholder and the Weed Management Branch with the successful management and potential future eradication of this very significant threat to industry. Monitoring surveys at the incursion site are ongoing with the number of individual seedlings being found decreasing steadily over the Dry Season. A Weed Spread Prevention Plan has been put in place by the landholder to minimise the risk of weed spread. Rubber vine infestation affects a wide range of landscapes in Queensland but has not yet established in the Northern Territory. A recent incursion near the Queensland / NT border is currently under management by the landholder and Weed Management Branch. More than 500 plants were found and treated in March 2019. Follow up monitoring and control efforts by the landholder have resulted in an excellent level of management of this particular weed infestation. Further surveillance target areas are being prioritised with survey work planned later in 2019 and into 2020. An IAP allows for collaboration and coordination of control efforts, but equally as important is the best practise weed data management that it delivers. This includes the trace back of probable incursion pathways and the prediction of future infection risks. An IAP allows for the identification and prioritisation of likely areas of risk rather than simply waiting for the next weed to be found. The Weed Management Branch is currently finalising surveillance priorities for parthenium weed and rubber vine across the Katherine and Barkly regions. Pastoral properties have assisted with this essential work by contributing to a survey earlier in 2019. If you would like to talk to a weed management officer, please call (08) 8973 8857 (Katherine) or (08) 8999 4567 (Darwin) or for more information visit nt.gov.au Proactive planning and sharing the load makes future weed incursions easier and cheaper to manage. We’re all in this together! Above: An immature parthenium plant Right: Survey crews identifying parthenium weed outbreaks Below: The first surveillance team for the rubber vine response No cabomba seen in Darwin River for nearly 3 yearsCabomba (Cabomba caroliniana) was first reported in Darwin River in 2004, which was the second significant sighting of it in the Northern Territory. It was previously found in Marlow Lagoon in 1996 and was eradicated. The last plant found there was in 2002. Cabomba is a significant risk to the Northern Territory’s freshwater systems as it is highly invasive and is capable of choking out our favourite fishing spots, or even our drinking water in Darwin River Dam. It is a declared weed in the Northern Territory and is also a Weed of National Significance. Northern Territory Government weed officers have been controlling cabomba at Darwin River since its discovery in 2004. The Weed Management Branch is happy to report that after an intensive and renewed spray program, it has been almost 3 years since there has been any cabomba detected within Darwin River. Unfortunately, not being able to see it doesn’t mean it isn’t there. We do know that where cabomba has been treated in other locations around Australia, it has been undetectable for 4-5 years, but has since come back. Recent developments in the detection of cabomba environmental DNA (eDNA) has shown that cabomba eDNA is detectable in water samples from Darwin River. The positive detection of cabomba eDNA is a concern but the testing cannot distinguish between eDNA from viable cabomba and eDNA from dead or decaying cabomba, known as legacy eDNA. Therefore, the Weed Management Branch will continue to monitor the Darwin River for cabomba for around 10 years since its last sighting in 2017 before safely saying it has been eradicated. Until further notice, quarantine zones are still in place. Weed management plan newsThe Weed Management Branch has developed a number of species-specific weed management plans under the Weeds Management Act 2001 (the Act) that set out additional requirements for landholders and landowners in addition to general requirements outlined under the Act. A total of 10 statutory weed management plans have been developed and are available at: nt.gov.au. In accordance with the Act, these plans must be reviewed at least every 3 years. The neem, prickly acacia, mesquite and chinee apple plans are currently under review and are close to being finalised. Key stakeholders will be informed once the review process is complete. Review of the Cabomba Weed Management Plan and Grader Grass Weed Management Plan has also commenced. You can ‘have your say’ on the review of these plans at haveyoursay.nt.gov.au until 7 February 2020. For further information on the review of these plans feel free to call the Weed Planner on (08) 8999 4567. Above photo of cabomba leaf NT WeedMateThe NT WeedMate is a mobile app for iOS (Apple) and Android (Samsung etc) devices designed to collect weed data points for general mapping purposes. It works offline and can be taken anywhere in the NT. The NT WeedMate was developed by the Weed Management Branch to assist with the efficient collection of weed data. The app is targeted at contractors, land managers and consultants; anyone who needs to record weed data in a reliable, systematic way. NT WeedMate is designed to be fast and easy to use in the field, which lets people get on with the business of controlling their weeds. The NT WeedMate collects information about the weed species, density and location of the weed. Additional information such as treatments, chemicals and growth stages can be collected if desired. The app provides users with option buttons and drop lists to choose from so entry is fast and accurate. When data has been collected it can be viewed on a webmap, loaded directly into ArcGIS, or requested as a shapefile. Users need a (free) ESRI account to access their data and users can only access the data that they submit. To get started you need to download and install a current version of “Survey123 for ArcGIS” and add the NT WeedMate App. All the links you need to install and starter instructions can be found at: nt.gov.au. Organisations which adopt NT WeedMate can contact the Spatial Data Manager at the Weed Management Branch via email weedinfo@nt.gov.au and have staff, project or weed lists tailored to their organisation. The NT WeedMate journey is just beginning and we are looking forward to new functions and features in the future. News from AliceCutting declared cacti out of your life is a necessity!Alice Springs weed management officers will be busy over the coming months inspecting gardens in Alice Springs township and surrounding rural areas for any declared cacti varieties. These cacti varieties are declared weeds and Weeds of National Significance, due to their invasiveness and environmental impacts. Alice Springs residents are being urged to check their gardens and remove any declared cactus and dispose via the kerbside wheelie bin, which is part of the “Bin it Don’t Spread it” campaign, and to contact Alice Springs weed officers on (08) 8951 9210 for advice on how best to identify declared cacti. Buffel grass in the Todd RiverGetting their hands dirty is all in a day’s work for Alice Springs weed management officers. During the past 18 months the Weeds Branch has been managing herbicide efficacy trials to control the spread of buffel grass in the Todd River. More recently, we’ve been taking a hands on approach to protect the iconic River Red Gums of the Todd River, as part of the Alice Springs community’s Lhere Mparntwe Management Strategy. Working with Prison Work Crews, weed officers have been cutting fire breaks around monitoring sites and demonstrating to the prisoners how to slash and rake collars around the trees, in preparation for planned burns by NTFRS and Bushfires NT Volunteers. All this in an effort to protect against wildfires. The River Red Gums mark the travels of caterpillar and other Dreaming ancestors through the town. Respecting and caring for the rivers gums is a central part of cultural maintenance for Mparntwe custodians, who regard these trees as their kin. The protection of the trees is therefore a central part of the management strategy. Through the efforts of the Weeds Branch and up to 40 prisoners, work to reduce the fuel loads in the Todd River ahead of summer is well advanced. Biocontrol newsA new approach to on-ground biocontrolWhen we talk about managing weeds, there are some fascinating approaches that can complement traditional management practices, and in many cases even reduce the need for chemical and physical control. This green sida beetle (Calligrapha pantherina) has successfully controlled many spinyhead sida infestations by literally eating them down to the ground. It’s an easy and cost-effective way to manage the boom and bust cycles of sida, and after many years of the Weeds Branch breeding and distributing the beetles as a public service, now it’s time for the public to breed and trade them amongst themselves. The trading network, dubbed the ‘Green Beetle Club’ for now, is a new approach to biocontrol for the NT, following in the footsteps of the recent successes in salvinia weevil trading. Creating a market to produce and sell biocontrol agents like this incentivises land managers to conduct their own biological weed management, and integrate it into their best practice weed management systems on ground. Photos: top left: Calligrapha eggs on a sida leaf, top middle: Calligrapha larvae eating a sida leaf, top right: Young calligrapha beetle and to left: Mature calligrapha beetle. If you would like to be involved in buying or selling calligrapha please contact weedinfo@nt.gov.au and put ‘green beetles’ in the subject line of your email.
Territory’s biological control agent wakes up in ZambiaOur work in Mimosa biological control is being mirrored in Africa, with one of our ‘deadliest’ control agents being successfully harvested here in Darwin and flown to Zambia. The larvae of the moth carmenta (Carmenta mimosa) bore into the weed’s stem causing it to break off and die. The success of carmenta in the NT has prompted interest from the Centre for Agriculture and Bioscience International in Kenya, and with help from the Department of Agriculture and Fisheries in Queensland, plans were made to utilise the wild stocks of carmenta in the NT as a source population for introduction to Zambia. 234 live carmenta were imported to Zambia under permit and released into the wild. This involved drilling holes into the stems of the local mimosa infestation, and inserting live larvae (caterpillars) and pupae (cocoons) directly into the stems. Reports so far are that larvae movement has been observed within the stems, and adult moth activity has been detected at the release site. Encouraged by the success of this project, plans are being developed to use our local NT carmenta as a source for re-distribution throughout the Territory and beyond. Carmenta pupae in mimosa stem Staff in the field collecting carmenta Larvae being removed from stems for release in Africa |