Row cropping is more commonly associated with maize and soybeans, but these systems also contain clues on how to address some of our more difficult problems like weed control in lupins.

Australia’s $3.5 billion per year weed burden is as vicious on Western Australia’s one million hectare lupin crop as on any other crop type. Ryegrass has a particular liking for surging up between crop rows and setting seed to raise new generations, or dominate the seedbank for years. These pests compete for moisture, starve infant lupin crops and curb production.

Meanwhile, weeds also infiltrate the crop row itself, compete with lupins for often sparse resources and drag yield down by 25 per cent. Managing these weeds often calls for growers to use costly herbicides, especially if applying after seeding, when selective herbicides must be used to specifically target grass weeds.

However, Department of Agriculture research, supervised by Mike Collins and supported by growers and the Federal Government through the Grains Research & Development Corporation (GRDC), has creatively manufactured a way to slash the use of these expensive herbicides.

Rocket science is the key. Attached to a boom spray, ‘Row Crop Rockets’ have wheels which support shields that divide and isolate crop rows. Non-selective knockdowns are sprayed within the housing to take out everything that has emerged between the crop rows, while nozzles on the outside of the housings administer selective herbicides only to the crop row.

This allows growers to rationalise the use of selective herbicides which can cost $50 plus per kilogram – why run weeds over with a Rolls Royce when you can flatten them with a Holden?

Wheels and skirts on the rockets ensure knockdowns don’t get onto crops, while angled wheels reach under lupin canopies to broaden the intercrop zone, thereby narrowing the crop zone and further reducing the selective herbicide required.

Working with 10cm wide intra-crop rows, this technology can cut the sprayed area by 44 per cent for rows separated by 18cm, 72 per cent for separations of 36cm, 80 per cent for separations of 50cm or 90 per cent for separations of one metre. When a selective herbicide was applied using this technique during moist seeding in 2000 and 2001, ryegrass numbers fell by more than 90 per cent.