Harrisia cactus (2 problem species – Harrisia martinii and H. tortuosa) are natives of the Americas, probably introduced into Australia for their appeal as a garden plant.
|Local Land Services North West is funding a major Harrisia herbicide trial adjacent to Gunsynd Way, NSW side of the River at Goondiwindi. The trial site is signposted and accessable to the public. More information – CLICK HERE…|
Harrisia was first noticed as being a problem weed in the early 1900s, when plants started to establish in in large numbers in parts of central Queensland. Harrisia martini, in particular, has since worked its way south to the Goondiwindi area, and across the border into New South Wales.
In NSW, Harrisia martini now infests (in varying degrees) well in excess of 100 properties across the northern parts of Moree, Gwydir and Inverell Shires.
Harrisia cactus is mainly spread by seed. A new plant can begin to produce fruit within 6 months. As it further develops, that plant will easily average 50 fruit every year; each fruit contains 200-800 seeds encased in a sweet, sugary substance, very attractive to various species of birds
and other wildlife. Birds, especially, spread the seeds far and wide. Consider the mathematics! ONE PLANT X 50 FRUIT X 500 seeds = 25,000 SEEDS PER ANNUM!
Because Harrisia is so efficient at producing and dispersing its seed randomly over such large areas, tracking down new plants is a major problem. Often, by the time we find a new, isolated plant it has already produced fruit and so the seed has moved even further afield! Obviously, local vigilance is an essential requirement in slowing down the spread of this noxious weed.
IDENTIFICATION Harrisia cactus is a low-growing, jointed, cactus plant. Its runners spread out “like the tentacles of an octopus”. When the runners touch the ground they take root and spread out from that point again. The fruit – about 5-8 cm in size – is bright red when ripe. It splits open to reveal its seeds to birds, animals and ants.
THE PROBLEM Harrisia cactus can cause painful injury to animals or humans who accidentally walk into or otherwise touch a plant. The thorns easily puncture car and quad bike tyres, even heavy 4WD vehicle tyres. Harrisia is a prolific seeder, spreads quickly, and has the ability to eventually take over large grazing areas.
Ploughing is probably the only means of total eradication; Harrisia cactus cannot survive on lands under constant cultivation. But of course, this option does not fit every situation; and, it would also need to comply with local land clearing regulations.
Burning provides some temporary control – tops of plants are easily damaged but unless it is a really intense fire, the plant’s extensive root system ensures its survival. A controlled (and “approved”) burn does certainly assist as a prelude to a spot spraying program because it removes the grass cover. (Allow time for the plants to start to re-grow again so they will absorb the herbicide).
Biological control methods using a mealybug (Hypogeococcus festerianus) have been moderately effective in warmer areas of Queensland but results in NSW/Qld border areas have been very disappointing. In fact, the perception that the insects were going to be as good as the famous “cactoblastis” on prickly pear was one of the reasons Harrisia was allowed to get away in that area.
Mealybug is still doing good work in many of the original core infestations, especially where landholders have continued to move the insects around. But, landholders should not rely on the mealybug for controlling new and/or scattered infestations because these plants will only continue to produce more fruit. These situations call for a systematic herbicide application program of containment and eradication.
Chemical control is effective, but must be constantly followed-up to beat regrowth, missed plants and new seedlings! Herbicides work best when the plants are actively growing (spring-summer).
The Australian Pesticides and Veterinary Medicines Authority website (through labels and permits on its website) recognises the following, approved herbicides:
|Amitrole 250 g/L + ammonium thyocyanate 220 g/L e.g. Amitrole T Herbicide®||1 L / 25 L of water. Apply as a foliar spray when plants actively growing, in the warmer months, using a knapsack or high volume handgun spray unit. Re-spraying may be necessary in some cases. DO NOT apply more than 2 applications per year with a minimum re-treatment interval of 30 days between consecutive applications.||Expensive but efficient. Registered for use in Qld Also Permit PER14553 for use in NSW and Qld – permit in force 21 March 2014 to 30 June 2018. [Correct PPE is always important – very important with Amitrole!]|
|Triclopyr 240 g/L + Picloram 120 g/L
|1.0 L in 60 L diesel. Apply as an overall spray, wetting all areas of the plant to ground level.||Usually a very reliable spray. Expensive per litre, but one litre covers a lot of plants! Ideal for small infestations and isolated plants because stays mixed for a longer period. Very practical for a spray pack in the back of the quad/ute for treating new and/or isolated plants “on the run”.|
|Metsulfuron-methyl 600g/L Various trade names eg Brushoff®, Ally® plus a non-ionic surfactant||20 grams in 100 L water plus surfactant. Spray to thoroughly wet plant. (High volumes – beware collateral damage to desirable trees). Apply as a foliar spray when plants actively growing, in the warmer months, using a knapsack or high volume handgun spray unit. Re-spraying may be necessary in some cases. DO NOT apply more than 2 applications per year with a minimum re-treatment interval of 30 days between consecutive applications.||This mix is very inexpensive and therefore widely used for initial treatment of thick areas. Best results when applied in warmer months Oct-April. Registered for use in Qld, also Permit PER14553 for use in NSW and Qld – permit in force 21 March 2014 to 30 June 2018. (Please note: high volume application can cause collateral damage to desirable trees!)|
|Triclopyr as butotyl (75 g/L) + metsulfuron methyl (28 g/L) e.g. Zelam Brush Weed Herbicide®||500 mL/100 L water Spray to thoroughly wet plant using water volumes to 1000-1500 L/ha.||Follow-up treatment may be necessary. Registered for use in Qld only – PLUS Also Permit PER14553 for use in NSW and Qld – permit in force 21 March 2014 to 30 June 2018.|
|Triclopyr as tea (200g/L) + picloram as tipa (100g/L) eg Tordon DSH®||2.5 L/100 L water Folia application||Registered for use in Qld only|
|Triclopyr (200g/L) + picloram (100g/L) + aminopryalid 25 g/L e.g. Tordon RegrowthMaster®||2.5 L/100 L water Apply as a foliar spray when plants actively growing, in the warmer months, using a knapsack or high volume handgun spray unit. Re-spraying may be necessary in some cases. DO NOT apply more than 2 applications per year with a minimum re-treatment interval of 30 days between consecutive applications.||Registered for use in Qld only Also Permit PER14553 for use in NSW and Qld – permit in force 21 March 2014 to 30 June 2018.|
|Stinger™ Herbicide 375 g/kg Aminopryalid present as the potassium salt + 300 g/kg Metsulfuron-methyl||40 grams in 100 L water plus wetter||Registered for use in Qld only. Spray to thoroughly wet using water volumes of 1000 to 1400 L/ha. Follow-up treatment may be necessary. Note withholding period restrictions (left)|
|Triclopyr 300 g/L + picloram + aminopyralid 8 g/L eg Grazon Extra®||500 mL PLUS 500 mL Uptake spray oil per 100 L water. High volume folia spray. Refer to permit for more details LATE MAIL: Results of current herbicides trials indicate Grazon Extra® seems to have an edge on the generic brands. Also, please note comments below in relation to using lesser rates during the warmer months:||Permit PER14442 for use on all cactacae species in force 23 October 2013 to 30 June 2018 – NSW only.|
|Triclopyr 300 g/L + picloram 100 g/L eg Grazon DS®, Ken-Zon®, etc|
|Metsulfuron-methyl (eg Brushoff®, Ally® etc) 600g/L PLUS Triclopyr 300 g/L + picloram 100 g/L + aminopyralid 8 g/L eg Grazon Extra® PLUS 250 mL spray oil or at least 100 mL wetter
Metsulfuron-methyl (eg Brushoff®, Ally® etc) 600g/L PLUS Triclopyr 300 g/L + picloram 100 g/L eg Grazon DS®, Ken-Zon® etc
|Grazon DS® equivalents or Grazon Extra®: This permit allows variation of rates between 150 mL and 350 mL per 100 L water to suit current climatic conditions. Webmaster’s comment: Metsulfuron-methyl (e.g. Brushoff®) on its own is very cost-effective, but during the cooler months (eg MAY-SEP) this same mixture works very slowly – too slowly in fact when a plant is starting to bear fruit.The addition of triclopyr/picloram (eg Grazon®) during the cooler months accelerates brownout and helps to stop fruit reaching maturity. Use the heavier rates (250-350) in autumn-start of winter (winter itself is not the optimum time to treat harrisia) – taper this off to minimum rates as the weather warms up again in the spring. Be aware heavy rates eg >350mL used during the summer months are more likely to fail because the mix works too quickly, causing the plant to shut down before the herbicide has had time to work its way through the root system. The plant will die off, but there may be excessive re-growth from the butt. Les Tanner 2 Jan 2015||Please see Permit PER80069 for full details. Registered for use in NSW and QLD – 13 January 2015 to 30 June 2018 For use in pastures, non-crop areas, commercial and industrial areas, domestic and public service areas and rights of way. Apply to actively growing plants. Some retreatment may be necessary, particularly with large clumps. DO NOT allow spray to drift onto sensitive areas including, but not limited to, natural streams, rivers, wetlands or waterways and human dwellings. Apply using a knapsack or power spray. Follow all label directions in regard to the use of Grazon near or in sensitive habitats that may be damaged by the use of these chemicals|
Herbicide trials are continuing…
For an update on the current situation in New South Wales go to the harrisia herbicide trials page in this website >>
MORE INFORMATION Queensland’s Department of Agriculture, Fisheries and Forestry has had a long involvement with managing this (predominantly-Queensland) cactus… see their informative webpage http://www.dpi.qld.gov.au/
DISCLAIMER: The information contained in this web site is based on knowledge and understanding at the time of writing. However, because of advances in knowledge, users are reminded of the need to ensure that information upon which they rely is up to date and to check currency of the information with the appropriate officer of North West Weeds or the user’s independent adviser.