... and other weeds
The Australian bush is under constant threat of invastion from weeds of all types. There are a number on Istari including camphor laurel, moth vine, mist flower, crofton weed, lantana, mickey mouse plant, senna and cats claw creeper vine to name a few. It is a long list!
Cats claw (Dolichandra unguis-cati) is one of the worst of the environmental weeds found in this region. It gets its name from the claw like tendril which attaches to the host vegetation, enabling it to climb and run up the trees.
This South American vine loves the sub tropical climate of the Clarence valley and thrives along the banks of its creeks and rivers, gradually covering the trees and eventually killing them by smothering or causing the tree to fall over from the weight of the vine.
Spring is flowering time for cats claw. The yellow flowers and prolific growth made it common in gardens earlier last century but unfortunately it forms a multitude of long seed pods releasing thousands of seeds with feather like wings to drift on air and water. These seeds sprout forming a carpet across the ground choking anything else from coming up.
Driving up the Clarence valley during spring you can see the extent of the infestation in the valley as the plants display their yellow trumpet flowers. Our infestation started along a major creek on our boundary which has now spread up stream of the larger creek and into the smaller creeks and gullies.
Spreading cats claw
Cats claw is very difficult to manage. Each new plant produces a tuber. One small tuber at first but as it grows it sends runners across the ground on their inevitable quest for something to climb up. At intervals it sends out extra roots for new tubers to grow, usually forming a chain of many tubers. These tubers can grow to the size of a very large sweet potato!
When the vine reaches a taller plant it grows up the plant looking for light. Trees become the ideal place for the vines to grow quickly running up and eventually smothering the host plant. When they get big enough to reach the tops of the trees, they flower and seed. The seeds drift down around a large area around the tree. Sometimes the seeds fall into water which are easily transported, floating on the water.
Cats claw control
Cats claw is considered an environmental weed. It doesn't harm cattle or other domestic livestock but covers the trees eventually killing them. Cattle will eat the vine however, as cats claw grows along streams banks, the cattle are clambering up and down banks causing their own damage to the waterway. In some cases the cattle may keep the cats claw down but only on the ground. Cats claw that makes it up the tree will continue to cover the tree, producing large amounts of seed spreading the weed further.
There are no native biological controls although some imported insects are being tested at the moment. These trials have been concentrated in south east Queensland and now in northern NSW. There is little specific information on the progress of these trials but you can check out the websites below outlining these possible biological controls. This method of control will not kill the cats claw already established, only slow its spread.
As the plant grows the vine's stem will grow and can get to plate size diameter in the extreme! At this size they can look like a tree trunk, not a vine, especially if their original support has died, leaving the vine stem standing independently. The vine is relatively soft so can be easily cut but at this size it is best cut with a chainsaw.
Alternatively a hole can be drilled into the vine, making sure it doesn't go through to the tree, then the herbicide is injected into the hole.
Cutting the vine at the base of the tree will, of course, kill the upper parts of the plant but will not kill the plant. The cut vines will quickly re-shoot sending many runners back up the tree. This can happen in less than a season!
We have tried pulling the tubers out, cutting the bases and finally poisoning. Poisoning is the only way we have found to control this weed with any real effect.
Glyphosate
We dislike using herbicides. In fact we tried to not use it for many years. One season was spent sitting on the forest floor pulling out the small plants. This took ages and given the many hectares of infestation would never provide a control. If you have a very small infestation you may be able to remove it by hand but otherwise physical removal just doesn't work.
There are a couple of herbicides which are effective on cats claw but glyphosate is the most common one used. Glyphosate was initially marketed under the name Roundup but there are many brand names with the same ingredient. Some also indicate the concentration of the herbicide, like 360 which indicates 360g/litre of glyphosate. Although this is a very common poison used in agriculture there may be health issues associated with its use - see some links below for more information on this.
All precautions should be taken when using this or any herbicide. Always wear gloves when handling the chemical. Ensure you are suitably dressed with a long sleeved shirt and long pants. Wear a mask if spraying. Follow the directions on the use and application. Avoid skin contact.
Application methods
There are a number of ways to apply the herbicide depending on the size of the plant.
foliage spraying - spray the leaves
cut stems (larger than a pencil diameter) and paint/paste/spray cut stem with a more concentrated dose
scrape stems to remove the bark exposing the stem then paint/paste/spray scraped stem - this is helpful if the stem is difficult to cut
drill stems then inject herbicide directly into the stem - used for very large stems
Glyphosate is a foliar herbicide. It is absorbed through the leaves when the herbicide is directly sprayed on the foliage. Once absorbed it inhibits a plant enzyme which in turn stops a growing process within the plant, eventually killing the plant. This may take some time, usually many weeks, to see results.
The photos above show patches which took five to six weeks to completely kill the plants sprayed. Even then some will survive and will need follow up, spot spraying the surviving cats claw.
The poison is most effective on a growing plant, particularly the growing tips which are reddish, so winter and dry periods are not recommended times for foliar spraying but I have sprayed in winter with some success. It will take some hours for the plant to absorb the poison so don't spray if it is going to rain. It will need at least several hours after the application to be effective.
Glyphosate is non specific so will affect all plants (except for some genetically modified plants specifically designed to not be affected by glyphosate). Spraying must be done with care. Don't spray on windy or even breezy days as you can't control where the mist drifts which may kill wanted native plants.
As a non specific herbicide it is difficult to spray the cats claw when already smothering low bushes like young trees, lomandras and ferns. Take extra care in these situations. We try to spot spray directly on the cats claw leaves, avoiding the leaves of the covered native plant. You can sometimes pull off some of the vine and spray it away from the covered plant. When cats claw infests ferns like forest fern, try to spray below the fern leaves where the cats claw is close to the ground. Dark stems won't be affected by the herbicide. There will be some collateral damage to some host plants but keep in mind the cats claw will kill the plant anyway by smothering it.
Large plants with stems larger than a pencil diameter need to have a direct application of the herbicide to the cut or scraped stem. The herbicide will be taken directly into the plant rather than through the leaves. The poison must be applied within 10 -15 seconds of making the cut, scrape or drill hole as the plant will seal the cut areas after that, stopping the uptake of the herbicide. The more herbicide you can have the plant absorb the more damage it will do. We have found scraping doesn't always work on thick stems if the scrape is not large enough so cutting is best. Similarly spraying even concentrated herbicide on thin stems won't be very effective. If the stem can be split when cutting, the herbicide applied to the cut and split will be more effective.
Where plants don't have sufficient herbicide applied to the stem or leaves it will re-shoot. The new leaves are easily sprayed in your inevitable followup.
Herbicide Concentrations
Glyphosate is a registered poison and although it can be used without special training the instructions for use must be followed. There is an Australian government permit, released by the Australian Pesticides and Veterinary Medical Authority (APVMA) outlining the requirements and concentrations of the herbicide for cats claw. The NSW Department of Primary Industries also has specific instructions for cats claw. This may differ from more general instructions from the manufacturer.
The APVMA has several mandated concentrations depending upon the use of the herbicide.
Spot spraying - 1:50 (one part herbicide to 50 parts water). This equates to about 20ml of herbicide to just under 1 litre of water.
Cut stem and paste or drill, axe or injection requires a more concentrated dose of 1:1.5 (one part herbicide to 1.5 parts water). This equates to 400ml of herbicide added to 600 ml of water to make up 1 litre on herbicide application.
Plan of attack
Controlling cats claw requires time, effort and discipline to eradicate.
You cannot control it in one go. Don't expect to kill plants and that is the end of it.
You need to plan to follow up regularly for several years. Make no mistake, it will take many years to clear an area of this weed.
Every single plant must eventually be killed.
After many years of trying to kill the cats claw here we have developed a plan of attack which we have finally found to be reasonably successful. It involves the repeated application of herbicide to affected areas.
The image on the right shows an area where the cats claw has been sprayed. Almost all of it died except for one plant which survived. Follow up is essential to get that last missed plant.
Our infestation is extensive and severe. The plant will gradually extend its range to adjacent areas where the conditions suit it if unchecked as it did with us. This may take years but it will take over.
The infestation starts out with a few plants from seeds spread by wind and floods. If you find young vines in most cases you will find a seeding adult plant nearby. These young plants rapidly grow and run up trees and bushes. Eventually they will develop flowers and seed which then will increase the concentration of infestation as well as extending the area covered.
Define Sections
For our extensive infestation we have found it best to divide the infested areas into sections to work on. We started closest to the house and worked with the least infected area and gradually moved on the more intensely affected areas. This will give you some hope as you see the results! The area should be of manageable size remembering that each section will be worked on over many seasons.
Essentially a section is worked on until no plants are found. Then leave this area for any hidden vines to regrow and new seeds to sprout. These plants are easier to see with ongoing inspection and necessary followup.
Equipment
Our equipment for low to medium infestations is
backpack sprayer
secateurs carried in a holder on your belt
a small bottle of more concentrated herbicide for the larger stems. We use a plastic 250ml sauce bottle in a holder attached to your belt.
Stage One - The first attack
The least infested areas will require spot spraying of the weeds along with locating and first treatment of any seeding plants.
We also take the time to eliminate any other weeds present. If you don't know your weeds it is worth taking a bit of time to learn which other plants are weeds. If you are working in an area you may as well get the other weeds too.
Spot spraying involves spraying individual or small clumps of the weeds you locate. It is slow but rewarding as you are working in the bush and get to appreciate the birds and other plants.
You will not see every weed plant but don't worry you will be back.
Any vines already running up the tree are pulled down onto the ground and sprayed there.
If the stems are thicker than a pencil they are cut using the secateurs and the concentrated herbicide is applied directly to the cut stem using the sauce bottle. You only need a small amount applied to the cut stem but it must be applied within 10-15 seconds cutting the stem. If possible, split the stem a little to expose more stem to the poison.
You can also apply this method for young camphor laurels, lantana and other woody weeds.
We carry a backpack with foliar concentration for the ground cover and low vines, secateurs for cutting larger stems and a small bottle of concentrated herbicide for the stems in this first stage.
If the stem is too big to cut you may need to resort to scraping the stem or drilling it and applying the herbicide. Sometimes this may require a separate visit. If so make sure you record the location.
Intense infestations
As you gradually move into the intensely infested areas the number of plants in the trees increases and these plants will flower and set seed. These plants need to be worked on first so that we can stop further seed developing.
Cutting these larger plants with secateurs is very difficult and time consuming due to the number and thickness of the vine. Trees in these heavily infested areas have their trunks completely covered by many cats claw vines, some of them large.
We use a machete or a chain saw for these areas or drill into stem.
When cutting the stems the cut is made around the tree base, about a metre above the ground followed by a second cut made closer to the ground, making sure not to cut into the tree. The gap cut into the stems should show up any missed stems. They can be even hidden in crevices in the tree. Pull the lower cut stems out to see if any have been missed.
The more concentrated poison is immediately sprayed onto the lower cut stems, within 10-15 seconds of the cut. We use a hand sprayer for quick application of the herbicide to the numerous cut stems.
This is easiest done with two people, especially when using a chain saw, one cutting and one spraying.
When working alone cut the trunk vines part of the way around the trunk then spray these cut stems then move around the trunk cutting in sections until all the stems are cut.
Check right around the trunk so that no vines are left uncut. The one you miss will be on the other side of the trunk.
This will kill all of the plant above the cut and the poison will effect the plant below the cut but often won’t completely kill the vines. You will be back to re-treat those vines that don’t die from the first application of the herbicide.
It is also possible to cut the stems, killing the upper part of the cats claw without poisoning immediately. It won't kill the plant without the herbicide application but it will stop the vine from seeding for a season or two.
After the stems re-shoot a foliar spray can be applied to the new shoots. This will probably have to be re-sprayed as the initial spraying won't kill off all the plants and tubers.
Where the stems are large we drill a hole into the stem and inject the herbicide into the hole. This method is also very effective for larger weeds species like camphor laurel, willow trees and other large woody weeds.
The images above show the size of the vine stem. We drill several holes and use a sauce bottle to apply the herbicide.
We find cutting around the trunks plus pulling cats claw down from the tree or bush in difficult situations is done first.
Next broadcast spraying is necessary where the ground is covered in cats claw. Spray the herbicide around the tree trunks already treated and the carpet of weeds spread across the ground. Pull the vines off bushes and spray these trying to keep the herbicide on the weeds.
Stage Two - The first follow up
There is no way you will find every plant (or even kill the ones that you have found) the first time or even the second time so follow up is essential. Hopefully you will have less plants each run that you do. You have to wait until the herbicide has taken effect before any follow up. This will be some time, around five to six weeks, as the herbicide does take time to take effect. If the first attack is done at the beginning of the growing season you can do the second attack later in the season. This gives you time to see where you have been and where you have missed. It is easy to miss whole patches. We add a dye to the herbicide which is helpful but not infallible.
Any plants that were cut and not killed will probably re-shoot by that time and you will be able to simply spray the foliage. If you leave it too long then the stems may need to be re-cut (yes they can grow really quickly) and the concentrated herbicide applied. Any plants running up the tree again are pulled down and sprayed once more.
Stage Three plus
As you work through each section you will need to return several times to continue to eliminate all the plants. This must be done in a timely manner as the remaining vines will recover and eventually cover the trees again then flower and seed, sending you back to the first stage again.
A seasonal check is essential. Check in October, when the cats claw is flowering, to make sure you catch seeding plants. Also look for vines running up the tree trucks. You will get your eye in.
Our Failures and the Lessons Learnt
Our first and most fundamental failure was a lack of understanding about the cats claw plant and its incredible ability to survive and multiply.
It is very difficult to kill and if left will grow very quickly in our subtropical conditions and then flower and seed, spreading thousands of seeds.
At first we resisted the use of a herbicide in our beautiful Australian bush. We were against the use of a herbicide. It was our biggest mistake. Initially I literally sat on the forest floor and pulled out the young plants. If you have a small area it may work but apart from that it is a waste of time.
We also simply cut the base of the vine, killing the plant up the tree. This does work (for a moment) but the tubers are big and quickly send up more vines running up the tree. These grow quickly to reach the tops of the trees then flower and seed. You are back where you started.
Next failure was to reluctantly use the herbicide to kill the stems running up the tree but not quickly enough on the carpet of weeds around the stem. Firstly cutting and poisoning the stems does not kill the plant in many cases so the vine will regrow. Also if the plant growing up the tree has already seeded there will be thousands of young plants on the ground. These will quickly run up the tree eventually seeding and you are back where you started from.
Cats claw grows very quickly in the right conditions. Within years it will run up a tree and then seed. The huge number of seeds quickly sprout and form a carpet stopping other plants from growing. These run up the tree and continue the process.
Our next failure was to not follow up in a timely manner. Not only does this not kill off all the plants but it allows the weed to seed and spread that seed over an ever increasing space where conditions allow.
Summary of Lessons
Accept the use of herbicides. It is the only way to control the weed. Of course use them with care.
Divide your infected areas into sections
Locate and kill the seeding plants where they are first, before they seed (around March).
Follow up in your selected section and spray the cats claw on the ground and over lower bushes.
Follow up looking for the plants you have missed. There will inevitably be a lot at first. Spot spray each section you have done at least once a year. Do this until you are certain there are no weed plants left.
Follow up each year or even more often. Search out the plant. The weed flowers in October so check for seeders then. The yellow flowers show off the plant in the tree but they only occur high up in the tree where there is light. If they are way up a tree it is easy to miss them. Look up for the flowers and down for the fallen flowers. Some larger stems running up the tree won't have flowers or leaves so are easily missed.
If you have a small infestation don't wait. If the conditions are right it will get bigger and then you have a major problem.
This may seem hard. It is. There is no alternative though. One of the most rewarding things is to see the bush recover from an infestation. It will take time but gradually the natives return with gusto.
It can be done with consistent and methodical work.