Barley leaf rust
- South Stirling
Kith Jayasena (DAFWA) reports that an Oxford barley crop at the stem elongation stage (Z31) in South Stirling has low levels of barley leaf rust. The crop was sown on 16 April. Seeds were treated with Vibrance at 1.8L/t, Imidacloprid at 1.3L/t and Tebuconazole at 60mL/t.
Kith says this is a reminder to growers to monitor crops that were sown in April and early May for diseases and take appropriate action accordingly.
Barley leaf rust appears as small, circular to oval pustules with light brown powdery spores on upper surface of leaves and on leaf sheaths in cases of heavy infection. Severe infections can result in shriveled grains and yield loss.
Leaf rust can occur throughout the season and develops rapidly in moist conditions when temperatures are between 15-22°C.
Around mid-March leaf rust was detected in regrowth barley (mainly Bass and Oxford) so early sown crops emerging into slightly warmer autumn conditions were at risk from early disease incursion arising from inoculum hosted on green volunteers.
Oxford is ranked as susceptible as a seedling and resistant as an adult, therefore under early disease pressure we might expect to see seedling/tillering infection but with effective adult plant resistance (APR) the infection should diminish as the plant grows.
However if the infection continues to progress at this early stage then it may need control prior to the APR becoming fully effective.
For more information on fungicide treatments visit the department’s Registered foliar fungicides for cereals in Western Australia.
It is important that samples of all rusts are sent for pathotype testing. Infected leaf samples should be mailed in paper envelopes (do not use plastic wrapping or plastic lined packages) along with your details and collection information (location, variety etcetera) directly to the Australian Cereal Rust Survey, Plant Breeding Institute, Private Bag 4011, Narellan NSW 2567. Free reply paid envelopes can be ordered from the University of Sydney.
For further details see the University of Sydney's Cereal Rust website and How to prepare and send samples for dispatch to the Australian Cereal Rust Survey.