Grains Research and Development

Date: 01.04.2002

Win Win: Spread risk and contain disease by Gary Alcorn

Beating Crown Rot

NORTHERN NSW wheat growers heard good news at the recent series of Grains Research Update meetings. Crown rot (CR) can be beaten by embracing an integrated systems approach where pulse, cereal and oilseed rotations playa critical role.

The really good news reported by successful farmers and researchers at Bellata and Boomi was long-term rotations with CR-resistant crops such as canola, chickpeas, faba beans, field peas, sorghum, sunflower, mungbean or cotton can break the disease cycle and return attractive profits.

In other words, farmers who focus on better paddock management and on crops other thanwheat can expect healthier winter cereals as well as increased returns by spreading their risk.

Kevin Moore and NSW Agriculture colleagues Andrew Verrell, Steven Simpfendorfer and Paul Nash plus the University of New England's David Backhouse urged growers to think of crown rot in terms of three distinct components - survival, infection and yield loss.

Dr Moore said, "We've found a suite of practices that interact nicely to beat CR - for best results, plan to combine rotations with other control strategies such as growing tolerant wheat varieties and controlling grass weed pathogen hosts like barley grass and phalaris in fallow and break crops".

Fallow management, plant nutrition and stubble reduction measures complete the total system approach to breaking the CR infection cycle while stabilising cropping income.

Trials in northern NSW have shown a chickpea rotation is very effective in controlling crown rot in a following wheat crop. Dr Moore warns that a single rotation phase may not be long enough to significantly reduce CR inoculum level, so it's a case of persistence pays off.

Current research at the Tamworth Centre for Crop Improvement combines agronomy and plant pathology in a series of experiments that are examining CR in terms of pathogen survival, crop infection and yield loss. The trials, which began in 2000, examine:

  • crop rotation - to demonstrate to growers the benefits of rotation in reducing crown rot inoculum (chickpea, faba bean, canola, sorghum). These treatments will provide an assessment of the rate of residue decline/inoculum displacement under different crops
  • fallow management - to define the effects of fallow management on crown rot (treatments: grazing, early burn, late bum, cultivation, no-till, short fallow and long fallow)
  • grass weed management - to demonstrate to growers the importance of in-crop and fallow weed control in reducing crown rot (treatments: low versus high weeds in wheat, chickpea and fallow)
  • water x nitrogen - to define the interacting roles of nitrogen and soil moisture as determinants of disease severity and yield. Water levels are being manipulated through the use of irrigation and rainout shelters
  • dose response - to define disease and yield loss associated with varying levels of inoculum.

"This work should convince growers that an understanding of these relationships is critical to their management of crown rot.

"This winter season (2002), wheat will be planted across all trials. Crown rot infection, stem base browning and whitehead development will be assessed and links between moisture x nitrogen, crown rot and yield loss established," Dr Moore said.

Program 3 Contact: Dr Kevin Moore 02 67631133 email kevin.moore@agric.nsw.gov.au

Region North, South, West