Frequently Asked Questions
SERRATED TUSSOCK, CHILEAN NEEDLE GRASS, PARRAMATTA GRASS, RATS TAIL GRASSES & AFRICAN LOVEGRASS
Serrated tussock, introduced into Australia in the early 1900s, probably as a contaminant in hay imported from Argentina, was first identified as a weed in 1935. However, no control was undertaken in NSW until the 1950s by which time it had spread widely due to the destruction of pastures by rabbits. By 1975 it occupied 680,000 ha mainly in the central and southern tablelands where 32% of all properties were infested. By 1995 870,000 ha were infested with another 2,000,000 ha at risk. In Victoria 130,000 ha are infested with 4.2 million ha at risk. In total serrated tussock has the potential to infest more than 10 million ha.
Chilean needle grass is often found in the same areas as serrated tussock. It is spread by animals rather than wind and has a characteristic annular ring below the seed head. It is of little nutritional value and in areas where an infestation exists tends to be a monoculture. African lovegrass has a very wide range from Victoria through NSW into Queensland. Parramatta grass and rats tail grasses occur in northern NSW and Queensland. These weeds are of little nutritional value and cause productive pastures to run down with resultant loss of production as the pasture composition heads towards a monoculture of weeds.
Where these weeds occur in non pasture areas loss of native grasses and environmental diversity will result affecting the total ecosystem.
Q: What is the difference between TASKFORCE® and FRENOCK®?
A: None. Both herbicides contain the same active ingredient. The National Registration Authority (NRA) has approved TASKFORCE® after rigorously examining assays of the product to ensure its purity conformed to the required standard. The product was then registered as a "mirror image" to FRENOCK®. TASKFORCE® contains the same active ingredient, sodium flupropanate, at the maximum concentration allowed by the NRA.
Q: What is the recommended usage rate for the grasses mentioned above?
A: For spot spraying use 200mL per 100 L of water & for boom spraying use at the rate of 2.0 L per hectare except for african lovegrass where the rate is 300mL and 3 L respectively.
Q: Is a surfactant required?
A: No. The active is mainly absorbed through the root system of the serrated tussock. After a minimum of 5 mL of rain the chemical will start to be absorbed by the roots. Adding a surfactant will not improve the efficacy and may cause unwanted damage to other plant species. Chemical drying on leaves will dissolve readily when rainfall occurs and find its way to the root zone.
Q: Is this a safe chemical?
A: All chemicals need to be treated with respect and in accord with the label directions and good industry practice. That being stated sodium flupropanate has been in use since about 1972 without adverse reports and the mammalian toxicity data indicate it is a very safe. Please feel free to ask your supplier for a MSDS.
Q: Glyphosate is cheaper than TASKFORCE®. Why use this more expensive chemical to boom spray paddocks?
A: The bottom line is that glyphosate will result in a virtual weed mono culture. The high rates needed to kill mature serrated tussocks and the other weeds will also "nuke" everything else in the paddock. The weeds will also die but due to massive seed banks a tremendous germination will occur and these seedlings will thrive without any competition. The result after 2-3 years will be a paddock where the dominant species is the weed. The carrying capacity will be negligible. TASKFORCE® will kill selectively and many desirable native and introduced species will thrive after weed removal. Due to the chemical stability of the active, flupropanate, TASKFORCE® will continue to kill emerging serrated tussock seedlings for up to three years and keep the paddock free of seeding serrated tussocks for up to five years. Therefore a treatment with TASKFORCE® has a long term affect.
Q: How long does TASKFORCE® take to kill?
A: TASKFORCE® is a slow acting herbicide and can take up to 16 months to kill serrated tussock although brown out will be obvious after 3-4 months dependent on soil type, conditions etc. The other weeds brown out and die a little quicker.
Q: What is the fate of TASKFORCE® after the serrated tussock etc. has been killed?
A: The active ingredient, flupropanate, is slowly translocated from the soil into the growing plant. It inhibits a biochemical pathway which results in the brown out ( 3 months) and death ( up to 16 months) of the serrated tussock. The plant then decays and the residual flupropanate is released into the soil and together with remnant flupropanate will act upon and kill seedlings for the next 3-5 years.
Q: Does TASKFORCE® sterilise the seed?
A: No, but .... because of the residual affect the active remains in the soil for up to 5 years (dependent on rate, soil chemistry, rainfall etc.) and this residue will kill germinating seedlings. Research by Dr. Malcolm Campbell of NSWAg has demonstrated that pastures boom sprayed will be free of seeding serrated tussock for about 5 years.
Q: How long before new serrated tussock seedlings become a seed source?
A: Seedlings do not become a source of viable seed until they are 1-2 years old. At this stage they can be taken out with much lower rates of TASKFORCE® than is necessary to treat mature serrated tussock.
Q: What's the effect of mixing TASKFORCE® and glyphosate on serrated tussock?
A: The addition of glyphosate will quicken brown out but reduce the overall kill. Research has shown that flupropanate on its own has the best kill. Small additions of glyphosate reduce the kill. For example, the addition of 1.5 L/ha of 450g/L glyphosate into mix containing the equivalent 2 L/ha TASKFORCE® reduced the kill from 100% for flupropanate alone to 96%. The kill was determined 16 months after spraying. The more glyphosate is added to the mix the poorer the long term kill. Even smaller quantities of glyphosate such as 0.5L/ha will reduce long term kill.
Q: What is the best time to spray TASKFORCE®?
A: TASKFORCE® can be sprayed at any time. TASKFORCE® needs to be sprayed before August to stop seedhead production in serrated tussock. During summer the flupropanate is maximally affective in killing serrated tussock. Application in autumn and winter is less effective in killing the weed than application in spring and summer. In addition, subterranean clover is severely damaged by application in autumn and winter but is unharmed by application in spring.
Q: Will TASKFORCE® stop serrated tussock seedhead production if sprayed in Spring?
A: No. If it is necessary to stop serrated tussocks producing seedheads as well as kill it a mixture of TASKFORCE® and glyphosate will be required.This mixture will not be as effective in killing serrated tussock as TASKFORCE® alone. The reason for the poorer kill of the mixture is probably due to the slow translocation of the flupropanate ( three months to have a noticeable effect) whilst during this period the glyphosate has had severe phytotoxic effects on the plant restricting the ability of the serrated tussock to translocate flupropanate.
To reduce or stop seedhead production its recommended to spray at least 2-4 weeks prior to seedhead emergence. 2L/ha TASKFORCE® plus 1.0L/ha of 450g/L glyphosate sprayed 4 weeks before seedhead emergence resulted in a 91% reduction of seedhead production; spraying with the same mix 2 weeks before resulted in a 98% reduction but spraying 1 week AFTER emergence only achieved 58% reduction.
Q: Is there any advantage in burning the serrated tussock infestation the winter prior to spraying?
A: Although serrated tussock burns readily in winter it recovers while most associated species are killed. Burning before or after the application of TASKFORCE® will reduce efficacy.
Q: Can grazing control serrated tussock?
A: Cattle and sheep cannot control serrated tussock by grazing even if supplemented with urea, molasses or blocks. Goats have been successful in controlling the weed when it constituted 10% of an improved pasture but failed when it occupied 50%. Stock forced to graze the weed will eventually die.
Q: Does soil type affect rate?
A: Research has shown that poorer rocky soils require maximum label rate application. On deep productive basalt soils it may be feasible to use lower rates. A specific recommendation cannot be made but it has been demonstrated that summer application is the most effective. If serrated tussock is infests poorer soils such as shallow shales consider a summer program.
Q: I want to kill the serrated tussock infestation and sow a pasture of sub clovers and perennial grasses. How long should I wait between spraying with TASKFORCE® and sowing the new pasture?
A: Spray out the old infested pasture in late spring with TASKFORCE® and re-sow in the following autumn. Do not sow the new pasture unless 100 mm or more rain has occurred since spraying.
Q: An 18 month old new pasture is infested with 8-18 month old serrated tussock seedlings. What options are available?
A: This pasture at Berridale NSW was sprayed with rates equivalent to 0.75 L/ha TASKFORCE® and resulted in a 100% kill of the serrated tussock seedlings without damaging sown pasture species of subterranean and white clovers, phalaris, fescue and cocksfoot. It is necessary to spray in late spring or summer to avoid damage to the sub clover.
Q: What restrictions are there on grazing stock or cutting hay from paddocks treated with TASKFORCE®
A: Areas receiving blanket treatment ( that is, treatment other than spot spraying ) are not to be grazed or cut for stockfeed for at least 4 months. The withholding period on spot sprayed areas is 14 days. Stock should not be grazed in treated areas 14 days prior to slaughter and lactating cows and goats must not be grazed in these areas. This restriction is stated on the label. Although the active, sodium flupropanate, is regarded as a very safe chemical this withholding period ensures sufficient rainfall occurs to dissolve the chemical off the leaves and transport it into the soil so that it can be translocated by the weed and begin working. If the chemical ends up being eaten by grazing animals prior to a rainfall event then efficacy will be affected. Research has demonstrated that high levels of the active fed to cattle is completely removed in the urine within 3 days.
Q: I have serrated tussock and chilean needle grass growing in amongst kangaroo grass and wallaby grass. Will TASKFORCE® kill these natives?
A: Although some native grasses ( e.g. kangaroo grass Themeda triandra, redleg grass Bothriochloa macra, poa tussock Poa labillardieri) tolerate 2 L/ha TASKFORCE® others ( e.g. wallaby grass Danthonia spp, weeping grass Microlaena stipoides) are killed by rates of 1 L/ha.
Q: A Blue Gum plantation is growing adjacent to a paddock I want to boom spray with TASKFORCE®. If spray drifts into the plantation will it kill the eucalypts?
A: No. TASKFORCE® has no affect on eucalypt species.
Q: I live in Queensland and am using TASKFORCE® to control giant rats tail grass. Is it okay to spray when very heavy rain events are expected?
A: No. If run off occurs before TASKFORCE® is incorporated into the soil by some lighter rain some chemical can be lost. This may reduce efficacy. If cyclonic downpours are a possibility spraying with TASKFORCE® should be delayed. Similarly if soil is saturated delay spraying as lighter rain may result in run off.
Q: What chemicals are compatible with TASKFORCE®?
A: Its recommended to use TASKFORCE® on its own but it is physically compatible with all chemicals tested except for the amine salt of 2,4 D. Its common to mix TASKFORCE® with other chemicals such as glyphosate particularly for a spray graze or with chemicals to control certain broadleaf weeds such as MCPA / clopyralid etc. In spot spray formulations TASKFORCE® seems to act synergistically with certain chemicals for control of woody weeds ; metsulfuron-methyl etc. These are not registered applications.
Q: I have some TASKFORCE® that is very old. Can it still be used?
A: TASKFORCE® is a very stable chemical and does not degrade either when left in the original packaging or when diluted ready for spraying.
Q: I have heard there may be some resistance to flupropanate in the district in the control of serrated tussock. What should I do?
A: Always use the label rate of 2L per ha. Do not use lower rates.
Q: I seem to be killing everything when I spot spray.
A: The rate for spot spraying most weeds TASKFORCE® treats is:
“200mL of TASKFORCE® in 100L of water applied at 1000L per ha”
You are probably over applying the spray. Try calibrating your hand gun. This can be done by marking out 10 sq metres; spraying the area as you would normally; record the time taken to do this ( in seconds) and then spray into a bucket or something similar for the same length of time. Measure the volume of water in a measuring cylinder and multiple by the factor of 1000. This is the quantity of spray you are applying per hectare. It should be around 1000L.
Q: I have a very heavy infestation of giant parramatta grass in amongst kikuyu. I want to really nuke the GPG by putting on twice the label rate – 3L/ha.
A: TASKFORCE® is a rate selective herbicide. If you double the rate from 1.5L/ha to 3L/ha you will start to reduce the selectivity without gaining any additional benefit. TASKFORCE® will kill the GPG and leave the kikuyu unaffected at 1.5L/ha.
Q: We have a council oval full of parramatta grass in amongst couch and kikuyu. Will TASKFORCE® selectively remove the parramatta grass?
A: Yes. Apply at 1.5 L/ha. Be careful to calibrate the boom spray carefully.
Q: I applied TASKFORCE® to a paddock of african lovegrass around 3 years ago and now its coming back. Why?
A: Using TASKFORCE® is the first step in a weed control program for ALG and the other weeds TASKFORCE® controls. After the weeds start to die you need to manage the paddocks so that the better desirable pasture species present spread. They need to take over from the perennial weeds like ALG which have died and they need to be allowed to go to seed so that over the next couple of years you get a denser pasture made up of better grazing grasses. This often means that grazing pressure needs to be reduced considerably at times. The great advantage of TASKFORCE® is its ability to selectively control these perennial grass weeds in a grass/legume pasture but it needs on going management to extract the full benefit. Try to maintain at least 1500 kg DM per ha – this quantity of competition to weeds makes it difficult for them to really get going.
Q: What’s the criterion to go from spot spraying to complete blanket spray?
A: In areas where there has been a heavy infestation for years its probable there is a big weed seed bank in the soil. This means that if you choose to spot spray you will have to go back again once or twice a year to spray misses and new germination. So many people use a rough rule of thumb of 1 plant per 10 sq. metres as the transition. This is 1000 plants per hectare. When boom sprayed the residual TASKFORCE® will kill germinating seedlings for several seasons unless the soil is very sandy or in very high rainfall areas which reduces persistence. Its important after boom spraying to go around the paddock and treat areas which could not be sprayed such as rocky areas, corners etc.
Q: Does TASKFORCE® leach?
A: TASKFORCE® binds tightly to the clay portion of the soil. It does not leach unless actual soil erosion occurs.
Q: I have a massive infestation of serrated tussock on a good basalt paddock and intend killing it and resowing pasture. There is not much in the way of any useful grass species left. What is the best way to go about it? I’ve heard it can be sprayed out with glyphosate alone. This would be cheaper than using TASKFORCE®.
A: If you spray out with glyphosate alone chances are you will get a massive germination of serrated tussock seedlings with the new pasture which will cause long term damage. The best approach is to spray out with TASKFORCE® at 2L/ha and glyphosate at 300-400mL/ha as a spray graze in the October preceding sowing the new pasture or crop. In autumn go ahead with the sowing. Note the plantback period is 100mL of rain.
Q: I have widespread chilean needle grass on 70 hectares of land, mainly spread from the roadsides. I have good improved pasture most on 2 years old with a mixture of clover and rye grass. What rate do I spray the taskforce?
A: The label rate is 3L/ha but 2L/ha will kill the CNG. However the 3L/ha rate is better as it gives longer residual control. TASKFORCE® will not affect rye grass and has little affect on clovers apart from red clover. After 50mLs of rain all of the TASKFORCE® will be incorporated but this is not the issue – you need to allow time for the TASKFORCE® to work and more importantly for the pasture to get moving to fill the voids left by the CNG etc. Treat it like a new pasture and you will get long term control.
Its also important to spot spray around fences, trees etc where boom spraying misses. Try to get rid of all the CNG so there are no seed sources. Use a water rate of 80-100L per ha. Getting TASKFORCE® on evenly is the key to residual control so that germinating seedlings pick up the chemical next year and the year after. You will get 4 to 5 years residual control. Bear in mind you will have a massive CNG seed bank so even application of the chemical will give you the best result.
Q: Should I add glyphosate to TASKFORCE® when spraying CNG in November/ December?
A: CNG has a unique reproductive capability and the use of glyphosate at these times may make no difference to the production of viable seeds and will kill desirable plant species hindering long term control. CNG produce seeds in the main seed head; in ensheathed seed heads at nodes up the stem and cleistogenes at the base of the plant. Seeds in the main seed head become obvious in October and flower in early November producing viable seed; the stem node seed ripens by late February and is retained in the stem until it ruptures in late autumn/winter and the cleistogenes seeds are mature by November.
This means that spraying with glyphosate at this time does not have a great affect on seed viability. To overcome the biological advantage of CNG consider spraying with TASKFORCE® alone in the period January to June ensuring the plant is severely affected by mid November. By grazing or mowing untreated CNG a secondary seeding can occur. CNG produces viable seed over a long period. Often cleistogene seed is the main seed found in soil. Getting the application timing correct together with the residual activity of TASKFORCE® will help in control of this weed.
Q: I was hoping to locate some information on TASKFORCE®/flupropanate and the MRL information for native fauna. I understand flupropanate is quite good in this respect but it would be nice to have an index or table to point to for specific information.
A: There are no MRLs for flupropanate. Apart from the fact that flupropanate is regarded as benign the work necessary to obtain the MRLs is quite expensive and would therefore threaten the commercial viability of the product. Flupropanate has been in use since 1972 in Australia. In that time there have been no adverse reports in respect of any animal species. Its quite possible the APVMA may require MRLs in the future for meat but I have not seen any suggestion this be extended to native animals though I suppose anything is possible.
TASKFORCE® in the overall scheme of things is a herbicide of relatively low volume but it does control several weeds of National Significance and is the only practical option for several other weeds. In this respect it is an important product. Since residue levels after a period of several days are likely to be nil it seems to me to be a waste of time going down this path. NSW Agriculture conducted a well designed experiment on dairy cows in 1983 the results of which showed no residue after 72 hours. The issue of the residual nature of flupropanate is a very important feature which greatly helps the efficacy of the product in controlling weeds like GRT.
Unfortunately some people shudder at the suggestion of a “residual” chemical and believe this to be an environmental or health threat. The fact is all chemicals are residual – the ones that do not retain herbicidal activity simply undergo some chemical change to form one or more other chemicals which are residual for varying lengths of time and these can accumulate in the environment. However in the case of flupropanate the chemical is very stable, does not appear to be metabolised and is excreted reasonably quickly.
Q: I was wondering if you could provide me with information on the TASKFORCE® pellets for GRT
A: We don't do pellets - we found the long and short term results are not nearly as good as the liquid and the costs are prohibitive for most people. The liquid is 745 g per L active whereas commercial pellets or granules are 89 g per L. So 3 x 20L of TASKFORCE® has a similar amount of active as 500 kg of granules. But more importantly it is a characteristic of the active not to leach in the soil. Therefore the granules give a polka dot sort of pattern where a patch of flupropanate is surrounded by an area containing no chemical. This results in a significant portion of the weed seed bank never being in contact with any flupropanate. These seeds can then germinate and so the residual period of control never occurs.
On trials we carried out on serrated tussock at various rates (about 10 years ago) and with various sized granules we found initial knockdown significantly less than liquid and long term residual control was unnoticeable.
Q: Do you see a downside to tank mixing glyphosate (apart from cost and the need to spray within the wet season)?
A: Glyphosate efficacy is best if the plant is growing quickly. So times when plenty of rain is occurring are best whereas TASKFORCE® can be sprayed in dry times. It will sit there until incorporated by rain. It is residual by adsorption onto clay. This residue kills germinating seeds. If you get very high rainfall prior to incorporation there is a risk of it being washed away from the target plant. So I don't recommend spraying in the wet season.
TASKFORCE® is also slow acting. So if you spray a while before these weeds really start to move with TASKFORCE® alone I suspect you will get reasonable control plus sterilise any seeds that may form. Repeated applications maybe at 2 yearly intervals will reduce the seed bank. There is no downside in tank mixing with glyphosate but if you spray earlier you may find it's not necessary. Certainly for late spraying adding glyphosate is necessary.
The Q&A's above are based on research available in the published literature as well as other published data and are believed to be correct however no responsibility for its accuracy or correctness is accepted by VeeDri (Aust) Pty. Limited. If in any doubt about the use of TASKFORCE® consult your agricultural advisor.