By Kate Wall
All herbicides will be more effective in long term weed eradication in lawns which have good weed management strategies. You can find out more about good weed management in lawns here. At some point using a herbicide may be required, regardless of the weed management strategy implemented, to eradicate weeds from a lawn.
In general “weed and feed” products are not recommended and can give unreliable results. This is due to the fact that the amount of fertiliser in these products is not long lasting enough to give the grass any competitive advantage, but can act to counter the effect of the poison on the weeds, making it less effective and possibly even contributing to herbicide resistance. In particular weed and feed products are not highly effective on very hardy weeds such as nut grass or oxalis, or weeds with a deep tap root.
Fertilising a lawn is best done before poisoning weeds. The fresh new growth on the weeds as they respond to the fertiliser is the most susceptible to the effects of the poison and will result in faster and more effective killing of the weeds. As the grass is also responding to the fertiliser, it is able to quickly grow and take the place of the weeds. Poisoning will be most effective 2 to 4 weeks after fertilising.
Glyphosate herbicides are not recommended for use on lawns as they are general herbicides and will also kill the lawn. Selective herbicides are available which act on broad leafed weeds and will not harm lawn grasses. Some care needs to be taken with selection as some of these selective herbicides are not suitable for use on buffalo grasses. Always check the label before using a herbicide to ensure it is appropriate to use on your lawn type.
Most commercially available lawn herbicide products contain at least 2 different active herbicides. This allows them to have greater effectiveness as different herbicides will impact more effectively on some weeds more than others.
Any herbicide which contains dicamba in the active ingredients is NOT safe to use on Buffalo lawns. This will include Amgrow Multiweed, Amgrow Kleen Lawn and Yates Lawn Weed Killer. These products are safe to use on other lawn types including Couch, Zoysia, and Kikuyu.
Herbicides which do not contain dicamba are safe on all lawn types. Some such as Amgrow Bin-Die are sold targeting specific weeds (in this case bindii) however they have the identical active herbicides in the same concentration as other products sold for more general purposes including Yates Buffalo Pro and Hortico Weed Killer for Buffalo. The hose on weedkillers Yates hose On Buffalo Pro and the Hortico hose on Bindii killer are also the same active ingredients but in a different concentration for easy hose on use.
Hose on applicators can make the job of weed spraying easy, especially for large lawns, but can also be unreliable in their tight hose connection and therefore their dose rate. They can be harder to control the direction of spray as compared to using a spray pack. If garden beds are accidentally sprayed while spraying the lawn, remove the hose and wash the herbicide off plants immediately. These products are broadleaf weed killers and will damage or even kill garden plants. In general the undiluted products are better value for money and allow the lawn owner greater control of where they are being sprayed.
Any of these products will be effective in killing weeds in lawns. Their effectiveness will be increased when combined with good weed management practices and improve the health of the lawn and soil. Repeated treatments may be necessary for particularly persistent weeds or heavily weed infested lawns.
Many of the herbicides advertised for specific turf weeds, such as the Amgrow Paspalum, Nutgrass and Clover Selective Weed Killer are effective for some of the tougher weeds, however are not considered effective against nutgrass. In treating nutgrass with a herbicide, only one containing Halosulfuron-methyl will be effective and even this one may require repeated applications. It is commonly available under the trade name of “Sledgehammer”. This product is also suitable for killing nutgrass in garden beds, but only in beds which do not contain bulbs or plants with underground tubers.
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