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Lance Wise, Bowenville, Qld

Herbicide + shallow cultivation double knock

An optical sprayer and disc chain combination has proved to be very effective in keeping weed numbers low on the Wise family farm at Bowenville, on Queensland’s northern Darling Downs.

Lance and Fallon Wise and Lance’s parents, Murray and Janette crop 1600 ha and run cattle on 45 ha of non-arable rocky ridges. The locality and soft black plains enable the Wises to grow a range of crops including sorghum, mungbean, chickpea, barley and wheat, along with the occasional crop of faba bean, millet and canola.

In an effort to reduce their reliance on glyphosate and overcome some of the disadvantages of long-term no-till farming, the Wises have reintroduced light cultivation and are moving toward more targeted application of glyphosate and other herbicide products using an optical sprayer.

“Our usual rotation is a legume followed by a cereal, such as mungbean, to sorghum and chickpea to wheat or barley,” says Lance. “We use either a short fallow or double crop to change from a winter to summer crop program and aim for at least one crop every 12 months from each paddock.”

Having been no-till farming for 25 years the Wises have seen the weeds transition to those species that proliferate in the absence of cultivation; weeds like fleabane, urochloa, feather top Rhodes grass, cow vine and bladder ketmia.

In an effort to reduce their reliance on glyphosate and overcome some of the disadvantages of long-term no-till farming, the Wises have reintroduced light cultivation and are moving toward more targeted application of glyphosate and other herbicide products using an optical sprayer.

Nine years ago they had success using the Kelly disc chain to manage urochloa on their less well-structured red earth soils. More recently they have used this implement to target herbicide tolerant feathertop Rhodes grass and fleabane on their main black clay soils.

“We are using a chemical / tillage double knock to good effect on feathertop Rhodes grass in the fallow,” says Lance. “We apply glyphosate and then follow up five days later with the Kelly chain, which does a terrific job of pulling out sick, dead and small plants at an operation speed of 11 to 12.5 km/hr.”

“The same system works well on fleabane too, pulling up plants with foot-long roots from soft soil, although a higher rate of glyphosate is required. It doesn’t work well for weeds like prairie grass that have deep, fibrous root systems.”

The Wises have found the chemical / tillage double knock to work well on feathertop Rhodes grass and fleabane.

Used in reverse order, Lance has found the light cultivation is an effective way to stimulate germination after a poor sorghum crop to sprout volunteers and then spray out the crop.

Along with the benefits of partial stubble incorporation on soil microbial activity and ease of sowing, Lance says the two short chains in the middle fill in the 3 m wheel track to even out the paddock, avoiding the need to do extra wheeltrack renovation operations.

About the Kelly chain

“We also use the Kelly chain to incorporate pre-emergent herbicide after sowing to a maximum depth of 2 cm. This does not disturb seed, which is all sown at least 4 cm deep with a presswheel, and the soil is moved sideways without destroying the cracks in the soil or drying out the profile,” he says. “Weed seed is not buried deeply so it doesn’t come back to haunt you years later.”

Lance avoids using the Kelly chain more than once in a season on the red soils, which can get very dusty and are prone to hardsetting on the surface.

At the end of harvest Lance and Murray assess the stubble load and weed pressure in each paddock. They usually spray glyphosate after a rain event and either double knock with the Kelly chain or spray paraquat through their Weedseeker optical sprayer.

After using the Kelly chain, Lance follows 30–45 days later with the Weedseeker rig to clean up any survivors.

“The Weedseeker is a new fallow option for us and means that we can treat weeds that we might otherwise ignore, apply higher rates, and use more expensive products to control small areas or patches of weeds,” says Lance. “The 36.6 m boom carries 96 sensors so there are not many weeds that go undetected in the fallow.”

At the end of last year, the Wises started sub-soil ripping to a depth of 35 to 40 cm on 75 cm spacing to increase water capture and break up the sub-soil compaction to improve crop growth.

Six weeks ahead of planting they apply the final glyphosate spray and then add fertiliser, which they incorporate with the Kelly chain, with the added benefit of removing any weeds present. Liquid fertiliser applied at seeding promotes early seedling vigour and growth, which gives the crops a competitive advantage over weeds.

They plant using a Tobin planter that achieves a good even strike in stubble, starting on the red soils as soon after rain as possible, then moving onto the black soils.

Pre-emergent herbicide is applied after sowing legume crops and incorporated using the Kelly chain. Herbicide is applied in crop as well as for desiccation purposes in sorghum, mungbeans and chickpea.

Being a spray contractor, Lance has also invested in an air boom on his sprayer that enables him to have much greater control of droplet size to match the environmental conditions, while also covering a larger area in a day.

He says the elliptical cone delivers spray in both a forward and rear motion to achieve better coverage, even at lower water volumes. The controls in the cab allow the operator to adjust the spray quality from fine to extra course without changing nozzles on the boom and there is no need to have all the different nozzles to suit different conditions and products.

The Wises operate a 12 m controlled traffic system and plant all their crops on 375 mm row spacings. Lance has increased the planting rate in sorghum from plants 40 cm apart in the row to 25–30 cm apart to quickly to shade the interspace and suppress weed growth.

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Can pulse cover crops tackle multi-resistant ryegrass in irrigated systems?

The best weed control comes from tactics that also bring other benefits to a farming system.
Greg Sefton, principal agronomist with Sefton Agronomics in the Riverina, says multi-resistant annual ryegrass is becoming a major problem in irrigated systems.
Greg Sefton, principal agronomist with Sefton Agronomics in the Riverina, says legume cover cropping is providing effective control of multi-resistant annual ryegrass in irrigated systems.
“Herbicide resistance can move easily through irrigation areas, particularly when the control methods used on the supply channels are limited to just a few herbicides,” he says. “The ryegrass here is generally accepted to have resistance to glyphosate (Group 9 [M]), Group 1 [A] such as clethodim, Group 2 [B] and Group 3 [D], such as trifluralin. Growers are now relying heavily on Group 15 [K] products such as Sakura, and doing their best to rotate out of the problem.”
To regain control, Greg is working with growers to incorporate a multi-purpose fallow crop such as field pea into the system as a winter fallow clean with the added benefit of contributing biological nitrogen into the soil ahead of planting rice or wheat. 
Earlier maturing varieties of field pea provide better weed control options than Kaspa field pea, chickpea and lupin, all of which generally mature later, sometimes after the target weeds have set seed.
“A competitive pulse crop terminated at maximum biomass is an excellent way to reduce weed seed set,” says Greg. “It is a cultural control that also enables the use of some herbicides that are rarely used in our system. Combining the herbicide and cultural methods in the WeedSmart Big 6 is an effective way to keep our cropping options open and to maximise the value of applied water.”

What is the best fit for the legume crop as a winter clean?
In brief: In the Riverina, the optimal place in the rotation is ahead of rice.
The details: Fields selected for rice production are usually bare fallowed for the preceding winter. The aim of the fallow is to control weeds and conserve soil moisture.
Some growers are having success with field pea sown in May as a winter cover crop then terminated for silage or as a brown manure in early September. This fits well with preventing seed set in annual ryegrass, including late germinating plants.
Field pea is a competitive legume and can suppress weed germination and growth when planted in the most competitive configuration possible with minimal soil disturbance and no gaps.
A knockdown treatment of glyphosate (Group 9 [M]), clopyralid (Group 4 [I]) and carfentrazone (Group G [14]) is applied at planting then a mix of pendimethalin (Group 3 [D]), clomazone (Group 13 [Q]) and paraquat (Group 22 [L]) is applied after an irrigation flush to initiate rice germination and prior to rice germination to knockdown both newly emerged barnyard grass (BYG) and persisting ryegrass. This provides a double knock on ryegrass whilst applying a pre-emergent herbicide for barnyard grass in the rice phase.
When implemented once every 4 or 5 years, with a diverse rotation of winter and summer crops in-between, growers can keep a lid on herbicide resistant annual ryegrass populations. 
Field pea is a competitive legume crop that can reduce annual ryegrass germination in the paddock and halt encroachment from the crop borders.
How do you manage weeds on the non-crop areas?
In brief: The same herbicide mix is applied to the whole paddock, including the weeds growing in the check banks.
The details: Weed seed, often carrying herbicide resistance genes, travels easily through irrigation systems and can colonise non-crop areas. Seed from these plants readily infests the cropping areas if not controlled effectively. The control measures used on non-crop zones are often limited to herbicide tactics, so it is important to make sure the herbicide is applied to maximum effect to prevent seed set.
Farm hygiene and physical removal of isolated weeds will also have a positive impact on weed seed production. 
What farming system benefits come with growing a legume cover crop?
In brief: A legume crop grown for biomass rather than grain can improved soil tilth and reduce crusting on some sodic soils. This practice also allows better soil nutrition management and keeps the grower’s options open if the water allocation situation changes.
The details: The field pea crop will fix atmospheric nitrogen and this allows the grower to use 100 to 150 kg/ha less urea to grow the following rice crop without any yield penalty. If there is insufficient irrigation water available for a rice crop, then the fixed nitrogen is still available for a winter crop of canola or wheat.
The phosphorus fertiliser required for rice can be applied when the field pea crop is planted, giving the phosphorus time to become more available in the soil and ready for uptake when the rice is planted.
Field pea is quite drought tolerant, so if irrigation water is not available for rice, the field pea can be grown through to harvest the grain and will usually yield 0.7 t/ha, which can be more profitable than, say, a 1 t/ha drought-affected wheat crop.
Building an integrated farming system based on methods that have multiple benefits is fundamental to staying ahead of weed pressure.
Practical tips for growing field peas as a brown manure crop
Pulses to attack weeds on many fronts

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Farm Business Management Factsheet

Key points

Effective decision-making is at the core of successful farm business management.
Making informed, logical and timely business decisions is crucial to achieving business objectivess.
Understand the different elements that influence how decisions are made and the possible outcomes.
Consider who is responsible for the final decisions in the different areas of your farm business.
Ensure the decision is finalised and implemented in a timely manner.

Want to link to this fact sheet/publication?

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The application of herbicides late in the season to prevent weeds setting seed or to desiccate crops must be carried out with caution and in line with herbicide label recommendations.
It is essential to check if these practices are acceptable to buyers, as in some situations markets have extremely low or even zero tolerance to some pesticide and herbicide residues.

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