News

Crop Disease Forecast 2008

Crop Diseases in Western Australia - Index of Publications

From an understanding of the biology of key plant pathogenic fungi it is possible to estimate the risks associated with particular diseases in key crops in Western Australia. Research undertaken by the Department has been used to develop tools to allow risk assessments to be made in the lead up to the cropping season. The information developed from these tools has been summarised on the linked pages below.

Blackspot management guide for field pea

Western Australia

Paddock separation (>500 m from last year's field pea stubble), crop rotation (at least 3 years between crops in a paddock) and the correct time of sowing are the key issues for the successful management of blackspot disease in field pea. Summer and autumn conditions determine when blackspot spores are released. Field pea crops should be sown so that the majority of blackspot spores have been released prior to the crop emerging. The "Blackspot Manager" forecasts blackspot spore production from infected field pea stubble at key locations throughout WA. Using this information and previous agronomic experience, DAFWA has provided regularly updated forecasts leading up to sowing in relevant regions. Using this information and previous agronomic experience, DAFWA regularly updates a detailed information on blackspot maturity . A time of sowing guide summary for field pea growers is also available.

South Australia

DAFWA’s "Blackspot Manager" is being tested for South Australian conditions in collaboration with Jenny Davidson of SARDI. Summer and autumn conditions determine when blackspot spores are released. Primary infection of blackspot is reduced if field pea crops are sown so they emerge after the majority of airborne blackspot spores have been released. The risk of air-borne spore inoculum indicated by the Blackspot Manager model is additional to the soil-borne risk measured by PreDicta-B soil tests. The model forecasts temporal pattern of blackspot spore maturity and release from infected field pea stubble at key locations throughout South Australia. Please read the interpretation of this forecast.

Canola blackleg risk

DAFWA's "Blackleg Sporacle" model predicts the onset of blackleg ascospore release from canola stubble for seven districts of Western Australia . Blackleg epidemics are primarily initiated by airborne ascospores originated from matured pseudothecia (fruiting bodies) of the fungus on previous years’ infected residues. Relatively lower temperature and moisture conditions during summer and autumn, favours the maturity of pseudothecia. Once matured, pseudothecia are triggered to release ascospore by rainfall or even heavy dews and high humidity. Early seedling infections are most critical as they are most likely to produce severe stem cankers and yield loss. The two most important blackleg risk factors are the proximity to infected canola residue and the timing of the first major ascospore release from old canola residues that synchronise with the seedling susceptible stage of this year’s crop. This information is shown in the Current forecast.

Cereal rust risk

Dependent on seasonal conditions, wheat in WA can suffer from outbreaks of three types of rust, stem, stripe and leaf rust. Barley, particularly on the south coast, can experience barley leaf rust. All have the potential to cause yield and quality losses. Rusts require living host plants to survive and the greatest yield impacts occur when early infections develop from rust survival and build up on volunteer cereals over summer- the so called "greenbridge" scenario. Initial outlooks for risk are assessed on seasonal conditions in lead-up to harvest 2007. Subsequent predictions will include the influence of specific summer and autumn rainfall (February-April updates) as conditions develop.This information is shown in the Current forecast.

For a chart of cereal foliar fungicides registered in WA, please see Cereal foliar fungicides registered for use on cereals in Western Australia.

Lupin anthracnose risk

The severity and occurrence of lupin anthracnose is dependent on seasonal conditions, particularly rainfall, and the level of inoculum present at the start of the season. Anthracnose inoculum arises from either infected seed or by rain splash of spores from nearby infected lupin such as wild blue lupin. Current forecast .

Cereal barley yellow dwarf virus (BYDV) risk

BYDV and the aphids that transmit it must survive the summer in living cereals or grasses, so BYDV risk is largely dependent on the availability of green vegetation in summer and early autumn. Local pre-season climate data is used to predict aphid migration and the amount of yield loss likely from spread of BYDV in cereals for each shire in the medium to high rainfall zones.

Lupin cucumber mosaic virus (CMV) risk

CMV is introduced to crops through planting infected seed, but the arrival of aphids that spread it is dependent on the availability of green plants in summer and early autumn on which aphids survive before crops are sown. Local climate data is used to predict aphid migration and the amount of yield loss likely from spread of CMV in lupins for each shire in the medium to high rainfall zones. This CMV risk forecast was developed in collaboration with CLIMA.

Lupin bean yellow mosaic virus (BYMV) risk

BYMV is introduced into lupin crops from nearby infected pastures. The arrival of aphids that spread it is dependent on the availability of green plants in summer and early autumn on which aphids survive before crops are sown. Local climate data is used to predict aphid migration and BYMV incidence in the medium to high rainfall zones of the West Australian grainbelt. Forecasts are provided as best-case, most-likely, and worst-case scenarios given the season to date and historical climate records. This BYMV forecast was developed in collaboration with CLIMA. This information is shown in the current forecasts.

Canola beet western yellows virus (BWYV) risk

BWYV is introduced into canola crops from external environmental sources. The arrival of aphids that spread it is dependent on the availability of green plants in summer and early autumn on which aphids survive before crops are sown. Local climate data is used to predict aphid migration and BWYV incidence in canola for the medium to high rainfall zones of the West Australian grainbelt. Forecasts are provided as best-case, most-likely, and worst-case scenarios given the season to date and historical climate records. This BYMV forecast was developed in collaboration with CLIMA. This information is shown in the current forecasts.

Greenness and green bridge

Greenness when viewed through time can give an indication of which areas may have a green bridge. Current greenness map .

Site designed, developed and maintained on behalf of GRDC project
“Managing disease constraints in Western Region farming systems”,
by Kawsar Salam
ph: (08) 9690 2216; fax (08) 9622 1902
email: ksalam@agric.wa.gov.au

Page updated: June 16th 2008