Rotation cuts the high cost of nematodes

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Image of Neville Loweskow and Neil Halpin

Neville Leoskow (left) and Neil Halpin.

The move to a cane/peanut crop rotation has dramatically changed the nature of farming for Bundaberg, Queensland district growers Neville and Jason Loeskow over the past 20 years.

Not only has it generated substantial improvements in crop productivity, input costs for the management of nematodes have also been slashed since the mid-1990s delivering savings of nearly $200,000 a year.

The Loeskows bought their 1600-hectare property in the 1960s and operated it as a cattle enterprise before expanding into irrigated sugarcane during the 1970s and 1980s.

However, by the 1990s they had begun incorporating peanuts as a rotational break crop to help control rapidly escalating root lesion (Pratylenchus zeae) and root-knot (Meloidogyne spp.) nematode populations.

In the past, the family regularly applied nematicide at a cost of approximately $2 per tonne of sugarcane produced; however, the introduction of a non-host crop such as peanuts into the farming system has meant that the costly nematicide applications are no longer required.

While that alone has heralded significant improvements to crop gross margins, Jason says there have been additional agronomic, yield and operational benefits from shifting to a legume rotation.

“On this marginal soil, it’s important to incorporate a rotation crop such as peanuts. It has increased our sugarcane yields to where we expect an autumn-planted crop to average 140t/ha, the first ratoon about 120t/ha and the second at about 100t/ha,” Mr Loeskow says.

“With no rotation, we had 80, 60 and 40t/ha on the initial, first ratoon and second ratoon respectively. This was largely due to no legume, no rotation and no break crop.

“It has also given us a wider range of options for weed control and enables us to keep our workforce employed for the full 12 months of the year as the peanut season fits into the quieter time of year for the sugarcane.”

Neil Halpin, Queensland Department of Agriculture and Fisheries (DAF) senior agronomist and project leader of the GRDC-funded Coastal Growers Solutions project, says nematode surveys have highlighted the severity and extent of the issue in the Bundaberg cropping region and therefore the need for growers to consider a long-term rotational farming system.

“Survey work undertaken by Dr Graham Stirling from Biological Crop Protection found that plant parasitic nematodes were a much larger issue in sugarcane-growing regions than previously thought with P. zeae found in every paddock sampled in the central coastal region of Queensland,” Mr Halpin says.

“Local trial work has shown that in a monoculture, six beneficial nematodes exist for every one plant parasitic nematode.

“However, after a rotation, that ratio changes to 136 beneficial nematodes for every one plant parasitic nematode, clearly demonstrating the enormous benefits of a well-planned and well-executed rotational cropping program to soil biology, soil health and plant production.

“The challenge remains to further improve soil health; to build suppression to adverse biology. Crop rotation, controlling traffic, retaining crop residues and reducing tillage are our current ‘tools of choice’ in managing the nematode threat in coastal sugarcane-based farming systems.”

More information:

Neil Halpin
Queensland DAF
0407 171 335
neil.halpin@daf.qld.gov.au

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