Hay beats weeds
Hay production is a central component of Aaron McDonald’s mixed farming operation near Horsham and it is helping to keep herbicide resistance in weeds at bay.
Farming with his parents, Greg and Leanne, Aaron runs 5500 ewes for wool and prime lamb production, utilising pastures, hay paddocks and crop stubble on their 4050 ha property.
The McDonalds are finding a rotation of canola, wheat, canola, wheat, then a double break of canola followed by faba beans or clover hay, is profitable and enables them to keep weed numbers down.
Aaron does most of their oaten hay production on the poorer soils but also uses oaten hay as an effective means to clean-up paddocks that have a higher infestation of ryegrass. Their clover hay is sold locally, predominantly as cattle feed, while their oaten hay is exported most years.
“Annual ryegrass and wild radish are our main problem weeds,” says Aaron. “We test for herbicide resistance every couple of years and so far the results have come back as ‘susceptible’ for most of the major groups. The main challenge we have with wild radish is the fact that it germinates all year round. With ryegrass it’s all about keeping plant numbers low.”
Although the testing is not showing herbicide resistance, Aaron is seeing evidence of Select not working as well as it did in the past. To add more mode-of-action diversity to their system the McDonalds are using pre-emergent herbicides Sakura and Boxer Gold in cereals with good success and grow both hybrid (RR and 650TT) and open-pollinated (TT) canola cultivars.
“The RR canola enables extra knocks with glyphosate in-crop to clean up paddocks where we are concerned over the efficacy of Select,” says Aaron. “All our other in-crop herbicides are still working well but we are trying to rotate as much as possible with Select and Edge, and using paraquat ahead of canola and glyphosate or paraquat ahead of cereals.”
The McDonalds have always sown their crops on fairly narrow rows, 250 mm spacing, and use high sowing rates (wheat and oats sown at 100 kg/ha and canola at 3.6 kg/ha) to provide strong crop competition to help with weed control.
The sheep grazing stubbles provides quite good control of summer weeds but some herbicide is always required. Aaron’s main summer weed concerns are melons and self-sown crop. In autumn or pre-sowing he occasionally double-knocks but often there are no survivors so the second knock is not needed.
Hay making and harvest weed seed control
Aaron has implemented narrow windrow burning for the last 4 or 5 years in their canola crops as a harvest weed seed control tactic to capture late germinating weeds. This is supported with strategic crop topping of the canola to desiccate and then windrowing 80 per cent of the canola area each year.
In their cereals, crops are cut low and stubble is burnt on about 75 per cent of the cropped area to allow easier sowing operation, and has the added benefit of destroying some weed seed. In barley crops the straw is often baled after cutting the crop low, allowing sowing without stubble burning. Grazing stubble and burning also helps reduce mice and slug numbers.
“Oaten hay production enables us to apply a desiccant over the top prior to cutting for hay,” says Aaron. “This gives us the opportunity to implement a herbicide plus non-herbicide double knock on in-crop herbicide escapes.”
“We graze the cereal stubble and canola narrow windrows after harvest but don’t leave the sheep on the paddocks for long,” he says. “We find that the cereals provide better feed value than the canola windrows but we also put lambs on the canola regrowth for a little extra green pick.”
Each year about 5000 lambs move through the on-farm feedlot, where the McDonalds feed out gradings from the barley grain and the straw. “Feeding the grain gradings out in the feed lot also brings weed seeds into the confinement area where we can control them quite easily,” says Aaron.