Blackspot Manager is a forecasting model for ascochyta blight (synonym: blackspot) of field peas. It can be used by agronomists and growers to help identify the best balance between early sowing and potential yield loss from ascochyta blight. Windborne ascochyta spores are released from infected stubble early in autumn, with timing depending on summer and autumn rain. Disease can lead to significant crop losses when the emergence of sown field peas coincides with spore release. Blackspot Manager calculates when the majority of ascochyta spores (~60%) have been released from field pea stubble and risk of infection is reduced to a low level.
DPIRD Crop Disease Forecasts 2019 are updated each week and contain predictions of blackspot risk (rated as low, medium or high). The forecast risk will decline if there is 3.5mm or more of rain each week. If no rain occurs then the risk for the forecast period will remain the same as in the first week. Growers can decide to delay sowing field peas until their region is designated as a low risk for blackspot, or if sowing when risk is high, they can plan a foliar fungicide program to reduce the severity of blackspot in their crops.
The optimum agronomic sowing window for field peas in each of the districts is also shown alongside the forecasts.
Blackspot Manager is produced by the Department of Primary Industries and Regional Development (DPIRD) as part of the GRDC National Pathology Decision Support project, and predictions are made for field pea crops in New South Wales, South Australia, Victoria and Western Australia. Forecasts are regularly updated from April through June, each year.
Subscribe to Blackspot Manager
You can subscribe to the free SMS blackspot alert service through two methods:
- Text ‘Blackspot’ with your name and nearest weather station or location to 0475 959 932
- Email your name, phone number and nearest weather station or location to BlackspotManager@dpird.wa.gov.au
South Australia and Victoria
In 2019 early forecasts point to a high risk of blackspot in seedling field pea crops across most of South Australia and Victoria. The extremely dry summer and autumn has delayed the maturation of blackspot spores on field pea stubbles. This means the spores will not be released until sufficient rainfall has occurred and this will most likely coincide with new crops emerging and establishing. Growers should prepare for a high risk of blackspot establishing in their crops. Actual disease severity will also be determined by the number of rain days during the spread of the spores, since moisture on plants is required for infection to take place and disease to spread.
In Victoria, there was heavy rainfall in some areas, but spore release requires more days with rainfall rather than heavy rainfall on a given day. Therefore these areas that experienced heavy rainfall still have high blackspot risk.
View the latest Blackspot Manager forecast for South Australia here.
View the latest Blackspot Manager forecast for Victoria here.
New South Wales
In southern NSW the risk of blackspot to field pea crops is variable, depending on how much rainfall has been received. In eastern higher rainfall districts, such as Wagga Wagga and Cootamundra the risk of blackspot is low, due to rainfall over summer and more recent rainfall events that have driven the development and release of spores. In medium to low rainfall districts such as Temora and Griffith, the risk of blackspot remains medium to high due to reduced rainfall events delaying the maturation and release of spores from old stubbles. Growers are reminded to consider both the risk of blackspot and bacterial blight when preparing to sow field pea.
View the latest Blackspot Manager forecast for New South Wales here.
The dry summer conditions experienced across most of WA means that there has been very slow spore maturation on last year’s field pea stubbles in most locations except for the Mt Barker area. We are urging growers to delay sowing of field pea in all areas due to high disease risk at most locations. It is agronomically too early to sow in the Mt Barker area. Just a reminder that dry sowing of field pea is not recommended.
View the latest Blackspot Manager forecast for Western Australia here.
Growers should aim to plant this year’s crop at least 500m from field pea stubble, and if downwind from the stubble, where possible, increase this distance up to 1km since the spores are wind-blown.
It is advisable to avoid early sowing, where feasible. In medium to high rainfall districts, the sowing date can be delayed 2-3 weeks past normal opening rains without compromising yield. The spore numbers in the air will reduce over the 2-3 week window, so the blackspot risk will decrease. However, delayed sowing is not an option in low rainfall short season districts as associated yield losses will be greater than losses caused by blackspot disease. It is important to check the updated blackspot forecasts each fortnight.
Fungicide strategies are an option in field pea crops that have a yield potential of at least 1.5t/ha. P Pickel-T or a thiram seed dressing will reduce blackspot infection on seedling crops, and foliar fungicide sprays will reduce the spread of the disease in the crop. Sprays can be applied between 4-8 nodes; apply at 4-node if Blackspot Manager risk is high or disease is present but delay towards 8-node if disease is not yet evident and forecast risk is medium. A second foliar spray at early flowering will reduce the spread of the disease in spring. For maximum effect, always spray ahead of a rain event, since spores are spread during rainfall. Spraying after rain is generally ineffective. Please discuss your fungicide options with your local agronomist.
The Field Pea Disease Management Strategy for the Southern and Western Regions (PDF 760kb) provides recommended management strategies to minimise disease in Field Pea.
The Pulse Australia field pea guide provides Variety Management Packages which should be consulted for up-to-date, specific variety information, and resistance ratings.