Management key for serradella

Despite receiving significant industry and media attention over the past few years as an easy way to fix soil nitrogen, summer-sown serradella crops need to be carefully managed for weed control particularly when considering future rotations.

But if weeds are controlled early, serradella in the rotation can also prove to be a winner in the fight against weeds in both canola and cereal crops in later years.

Konnongorring farmer Peter Whitfield is continuing to see the benefits of a hard-seeded margarita serradella crop sown last year, but he said weed control in the crop had to be been carefully managed.

Mr Whitfield said cape weed had posed the biggest problem early on and had to be controlled with a broadleaf pre or post emergent Imazethapyr-based herbicide.

“We have grown Cadiz serradella in previous years, but last year we tried the margarita and dry sowed it in late March, and were very happy with its establishment,” he said.

“We have let it regenerate again this year, and it has established even better than last year, so it’s a good early crop to fix nitrogen in the soil for subsequent crops, and provide valuable sheep feed.”

Mr Whitfield said he planned to sow Roundup ready canola on the paddock next year.

“The serradella will regerminate again but it will be sprayed out early using glyphosate before we sow the canola,” he said.

“Following that, we’ll put wheat into that paddock in the hope that by that time, the paddock will be very clean, and we’ll keep it in a continuous cropping phase for a few years knowing we have those weeds under control.”

4Farmers general manager Neil Mortimer said the key to the successful incorporation of serradella in the crop rotation was long term-planning.

“Planning is critical, you have to be mindful of chemical residues and how serradella fits in the rotation for you,” he said.

“Using serradellas can be an excellent way to set up your paddocks, not just in terms of fixing nitrogen, but for good weed control for subsequent crops.”

He said a chemical such as Imazethapyr would give good early-season broadleaf weed control.

He said costs would be in the vicinity of $10/ha when using Imazethapyr.

“This could be followed by a grass selective such as Haloxyfop later in the season used in combination with grazing.”

“If you are concerned about resistance, consider an application of paraquat later in the season.”

Mr Mortimer said serradellas were most susceptible to budworm.

“Serradella is very tolerant of early-season pests such as red legged earth mite, but extremely susceptible to budworm,” he said.

Department of Agriculture and Food WA senior research officer Angelo Loi said it was critical for farmers to know which chemicals they could use to avoid residue issues in subsequent cereal crops.

“Farmers should read the labels on their products to understand the implications for future crop rotations,” he said.

“When growing serradella you can’t use any solpholnyl-based or clopyralid-based herbicides in previous years because it can compromise the growth of the serradella by pruning the root system and stopping nodulation,” he said.

Mr Whitfield said he hoped DAFWA would continue to fund research into serradellas and bisurrelas because of the importance of these pasture crops in cereal and canola rotations.

“While I run sheep, my cropping program is my main profit driver, and I have found the serradella is playing an important role in the entire farming operation,” he said.