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Know risk of blackspot before sowing field peas

Growers planning to sow field peas (pictured) in 2018 are urged to refer to the Blackspot Manager forecasting model before planting their crops. Photo: Arthur Mostead

Growers planning to sow field peas in 2018 are urged to refer to the Blackspot Manager forecasting model before planting their crops. Blackspot Manager, developed by the WA Department of Primary Industries and Regional Development in Western Australia as part of a Grains Research and Development Corporation (GRDC) investment, can be used by growers and agronomists to delay sowing field peas when risk of ascochyta blight (blackspot) infection is high.

Windborne spores are released from infected stubble in autumn, with timing depending on summer and autumn rain. Disease can lead to significant crop losses when the emergence of field peas coincides with spore release. Blackspot Manager calculates when most spores have been released from field pea stubble. By knowing when that risk is highest, the sowing date of field peas can be manipulated to minimise exposure to the airborne blackspot spores, particularly in high to medium rainfall zones with longer growing seasons. In addition, growers can use fungicides against blackspot in field pea crops with a potential yield of at least 1.5 tonnes/hectare.

Early forecasts point to a high risk of blackspot in seedling field pea crops in most of the growing areas of South Australia and Victoria in 2018. The extremely dry summer and autumn has delayed the maturation of blackspot spores on field pea stubbles. This means the spores will be released with rainfall in late autumn and winter, when the new crops are emerging and establishing. Growers should prepare for a high risk of blackspot establishing in their crops by delaying sowing dates where feasible, selecting field pea paddocks that are not adjacent to 2017’s pea stubble, and planning fungicide sprays where economic.

Information on the Blackspot Manager website, supported by the South Australian Research and Development Institute (a division Primary Industries and Regions SA) and Agriculture Victoria, is updated every two weeks from April through to June.

A text messaging service is also available to provide timely and regionally specific data straight to a subscriber’s phone. To sign up for the SMS alert service, text BLACKSPOT, your name and your nearest weather station or your location to 0475 959 932. A direct email service is also available which is well suited to agronomists with clients in multiple locations.

Source: GRDC

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