Anthracnose, blackleg and black spot diseases have respectively challenged the viability of Western Australia’s lupin, canola and field pea industries, but researchers have profiled these diseases to devise management strategies which should help growers fight back.

Blackleg and black spot regularly carve more than 10 per cent from canola and field pea yields, while anthracnose was so devastating when it arrived in Western Australia in 1996 that it wiped 200,000 hectares from the local lupin rotation.

Trying to understand how these stem and leaf diseases behaved in mediterranean environments drove a Grains Research & Development Corporation (GRDC) supported investigation, conducted by Drs Art Diggle and Moin Salam, both of the Department of Agriculture.

Starting with anthracnose and blackleg diseases, they developed a framework to predict disease spread and subsequently produce district scale forecasting so that practical, farm scale agronomic control strategies could be devised.

After establishing the accuracy of these systems, the team adapted the framework to black spot in field pea. With support from growers and the Federal Government, via the GRDC, this is now being tested, with initial results suggesting it is ‘spot on’.

The models revealed telling facts about the spread of anthracnose, blackleg and black spot. For example, initial seed infection determines the impact of anthracnose on lupin crops, with 0.0025 per cent infection causing just three per cent yield losses, while a still modest infection rate of 0.05 per cent could cost growers an 80+ per cent yield penalty. Seeds can be tested at AGWEST Plant Laboratories, Tel 9368 3721.

Variety selection is an important consideration in limiting anthracnose damage, with Myallie suffering a 15 per cent yield loss when planting 0.01 per cent infected seed in a wet season, while Wonga surrendered less than one per cent yield under the same conditions.

Blackleg modelling revealed a slower onset of ascospore showers in the northern agricultural region. Growers from that area should therefore sow as early as the break of season permits to prevent ascospore showers coinciding with canola’s susceptible early seedling stage.

Although risky, south coast growers could consider delaying sowing until after ascospore showers, but must weigh such a decision against the yield losses incurred from a belated seeding.

To limit black spot spread, the framework advised that new field pea crops should only be sown upwind from paddocks which had carried similar crops in the past two years. The disease can spread across farms, so growers should be mindful of their neighbours’ recent cropping history.

Delaying field pea sowing by two weeks in the southern agricultural zone could also contain black spot damage.