Barley disease update
Geoff Thomas (DAFWA plant pathologist) reports that they are very low levels of leaf rust (and powdery mildew) in barley buffers in a trial at Moora.
Eloise Dean (Elders) has found trace levels of leaf rust in Buloke barley at Yerecoin. The Buloke crop growth stage is flag leaf fully emerged to booting.
Sue Cartledge (DAFWA) has found leaf rust in her barley phenology trials at Northam on the Baudin barley and other varieties. The plants are at the booting stage.
James Bee (Elders) has reported leaf rust in a Bass barley crop at Gairdner. The crop is at the stem elongation stage. The grower missed a fungicide application two weeks ago and now rust is affecting 5-10% of flag -3.
Kithsiri Jayasena (DAFWA plant pathologist) has found barley leaf rust in Flinders barley crops in the Amelup area.
Kithsiri says the variety Flinders ranks as moderately resistant (MR)/moderately susceptible (MS) and possesses the genes Rph12 and Rph20. In the Great Southern region where there is high disease pressure, these crops need to be sprayed with appropriate fungicides, since the activity of Rph20 is temperature driven and we do not know when the gene will activate. Granger and Oxford should be managed in a similar manner as they also have Rph20.
It is recommended that growers spray any barley leaf rust infections early with a registered foliar fungicide because if the disease gets away it is difficult to manage.
For more information on barley leaf rust refer to DAFWA's Diagnosing barley leaf rust page.
- Nayerlup (near Borden)
Kithsiri Jayasena (DAFWA plant pathologist) has reported loose smut in a Hindmarsh barley crop at Nayerlup (near Borden). Approximately 50% of the crop was infected. The crop had been treated with seed dressing Jockey and Gaucho only.
Barley loose smut is a fungal disease affecting seed heads, which can cause yield losses. Infection is favoured by rainfall and high humidity during flowering. At heading florets are replaced with a compact mass of dark brown-black powdery spores. In the paddock look for scattered plants with black heads or bare flower stalks.
The fungus is managed by sowing clean seed or using fungicidal seed dressings. Barley loose smut trials have been conducted by Andrea Hills (DAFWA) at Wongan Hills and Gibson, where plots were sown with infected Hindmarsh seed that had various seed dressings. Results of these trials and information on correct seed application are available in the Control barley loose smut 2015 factsheet and the Controlling barley loose smut in 2015 page on the DAFWA website.
Growers are advised to ensure all seed sown receives an effective seed treatment as infected plants produce no grain on their tillers resulting in lost yield. The percentage yield loss is similar to the percentage of seed infection. Some of our markets also have a zero tolerance for this disease.
For more information on barley loose smut refer to DAFWA's Diagnosing barley loose smut page.
- Wongan Hills
Geoff Thomas (DAFWA plant pathologist) reports very low levels of powdery mildew (and leaf rust) in barley buffers in a trial at Moora.
Blakely Paynter (DAFWA) has reported powdery mildew in booting Baudin barley in a trial near Cadoux and booting Bass barley in a trial at Wongan Hills. In both cases it was a trace infection with less than five plants affected and no fungicides had been applied, except a seed dressing.
For more information on barley powdery mildew refer to DAFWA's Diagnosing powdery mildew in cereals and Management of barley powdery mildew in 2016 - fungicide resistance pages.
Laurence Carslake (Farmanco) sent a sample of LaTrobe barley to DAFWA exhibiting classical symptoms of scald infection. The barley crop is at Dudinin. The affected plants were at flag leaf stage and had scald symptoms on most upper canopy leaves.
Scald symptoms first appear as oval grey-green spots on leaves. The spots become elongated, often diamond shaped and bleached with a distinctive brown margin. Lesions usually join to form necrotic areas and the entire leaf withers and dies.
Disease may be widespread across a paddock arising from infested stubble or start as 'hotspots' and rapidly spread, favouring thick crop areas where humidity is high.
The fungus is carried from season to season on infected barley and wild grass residues, regrowth barley or infected seed that acts as an initial source of infection. Early sown crops develop higher levels of scald as they may be exposed to the heaviest release of spores from infected residues.
There are a range of foliar fungicides that can provide effective control of scald.
Management of the disease can be promoted through choice of more resistant varieties and avoiding double cropping or close proximity to last year's infective barley stubbles. Use of disease free seed and seed or fertiliser applied fungicides at sowing will also limit infection at early growth stages.
For further information on barley scald visit DAFWA's Diagnosing barley scald page.
Spot type net blotch
Blakely Paynter (DAFWA) has found spot type net blotch in a barley trial near Cadoux. Barley varieties infected are Granger, Gairdner and some non-released lines. The plants are at the booting stage and no fungicides had been applied, except a seed dressing.
For further information on symptoms and management of net blotches, see DAFWA's Diagnosing spot-type net blotch and Managing spot-type net blotch in continuous barley pages.
For more information on barley diseases contact Andrea Hills, Plant Pathologist, Esperance on +61 (0)8 9083 1144 or Geoff Thomas, Plant Pathologist, South Perth on +61 (0)8 9368 3262 or Kithsiri Jayasena, Plant Pathologist, Albany on +61 (0)8 9892 8477.