Weed Control Links & Resources
Research and case studies on everything weed control.
Common Pasture Weeds Guide (Landscape, SA)
This guide is very useful for identifying and using pasture weeds to read the landscape. It includes soil characteristics and management approaches including but not limited to; overly grazed or heavily disturbed soils, saline soils, poor drainage or waterlogged soils and compaction issues.
https://cdn.environment.sa.gov.au/landscape/docs/hf/Plant-Indicator-Brochure_Final-for-Web.pdf
Competitive Weed Tactics from WeedSmart & GRDC
On the back of increasing levels of herbicide resistance, researchers say crop competition can be used more effectively to manage in-crop weeds.
WeedSmart share their top 5 tactics to increase competitiveness and control weeds. The five ‘pillars’ of crop competition against weeds are:
- high seeding rates
- narrow row spacings
- improved crop competition traits
- superior soil health
- east-west sowing.
Peter Newman, WeedSmart’s western region agronomist, says multiple Australian experiments show higher seeding rates are effective in suppressing in-crop weeds.
When it comes to deciding which crop competition ‘pillar’ to apply first, Dr Borger says east-west crop orientation is worth a try because it has been shown to reduce weed set – for free.
“Changing crop orientation will not work in every system, but it is worth considering how this ‘free’ weed competitive tactic could work in your farming system,” she says.
Grazing Value of Summer Weeds
Grazing value of summer weeds
Some weeds can cause animal health issues (see Toxic summer weeds). Others have nutritional value to sheep which may be worth considering before deciding to spray them out. This page focuses on summer weeds.
Generally, a good quality sown perennial pasture will contain 30–50 per cent sown grass and 20–40 per cent subterranean clover with annual volunteer weeds making up the rest of the pasture. Our Mediterranean pastures (without summer responsive species) decline in energy and protein as the plants go to seed and then die off. High-quality pastures may retain sufficient quality to maintain dry animals for the duration of summer–autumn but poorer quality pastures cannot.
In the absence of a summer active pasture species (like lucerne), summer weeds can be of value. Green pick over summer can provide protein, which is a necessary component of the diet and is important for the digestion of the low-quality dry feed. Ruminants struggle to digest enough pasture when the protein drops below six per cent.
Recent work by Jess Brogden and Lisa Miller at Southern Farming Systems (SFS) has documented the nutritive value of weeds that grow during the summer-autumn (Table 1). Their work is published as a Weed Fast Facts on the MLA weeds hub and SFS website.
Impact of soil amelioration on weed ecology and control Impact of soil amelioration on weed ecology and control (2023)
The project focused on three main findings from the literature review; 1) weed ecology in response to changes in soil characteristics, 2) soil movement and weed seed burial following use of varying strategic tillage implements and 3) management of weeds in the years directly after amelioration. The work highlighted that weed growth was either less impacted by changes to soil properties than crop growth, or weed growth and competitive ability were favoured by the same amelioration techniques that favour crop growth.
MLA – Managing Thistles to Boost Pastures
Scotch, nodding and spear thistles are large thistles
that grow best on high fertility soils disturbed by cropping,
grazing or pasture management activities. They are strong
competitors and dense infestations reduce carrying
capacity as livestock avoid them due to their dense sharp
spines that damage hides, mouths and eyes and cause
vegetable fault in wool.
Management tips:
1. Controlling existing infestations
The key to managing thistles is to reduce seed-set
and germination, while encouraging a strong competitive
pasture. Reduce seeding using herbicides, grazing
management and physical control methods such as making
silage or slashing.
Pastures need to contain a minimum
percentage of desirable species (such as more than 20%
perennial grasses and 20% legume) to compete with and
eventually replace the weed. Pasture improvement tactics
such as light rotational grazing, fertiliser and deferred
grazing are required to achieve weed replacement.
Image of the DS NarrowFold seamlessly seeding through 1m high and dense thistle paddock.
Norman Seeds – Thistle management strategies
As with all weeds, the key to controlling thistles is controlling them when they are small rosettes. It also means you can use less chemical, spend less money on chemical and can be safer for pastures with clovers.
Thistles also respond to increases in soil fertility, and in particular nitrogen, so spraying early is a key action before their spring growth flush.
Management Tips:
- Vigorous pastures provide competition for germinating thistles, reducing seedling establishment
- Reduce seedling plants by early action on new thistles
Weeds in Western Australia – Paddy Melon (1959)
A third member of the melon group which must be classed as a weed in Australia, is the Paddy Melon (Cucumis myriocarpus), a plant which is more closely related to the cucumber than the pie melon.
WeedSmart – The Big 6 flyer
The WeedSmart Big 6 are a set of chemical, mechanical and cultural tactics to help growers control crop weeds.
The one page flyer is a great quick fact sheet offers a diverse approach that includes several chemical and non-chemical tactics which places downward pressure on the weed seed bank and reduces herbicide resistance risk.