Barley diseases and their control

Transcription

1 Barley diseases and their control Geoff Thomas, Kithsiri Jayasena, Andrea Hills & Jason Bradley Department of Agriculture and Food Western Australia GRDC Project code: DAW0229

2 Outline Barley leaf rust Variety responses (APR) Managing rust Seed dressing and in-furrow fungicides Spot type net blotch Disease spectrum

3 Barley leaf rust what favours disease Green bridge Early sowing green bridge interaction Susceptible host (eg. Baudin, Bass) Suitable weather 10-20C Leaf wetness (humidity)

4 Varieties field responses Variety Seedling (2-3 leaf) Adult (Grain fill) Major genes (not effective) Bass SVS SVS Rph3 - Scope S S - - La Trobe MS S Rph9.am - Spartacus MS S - - APR genes (effective) Flinders S MRMS Rph12+ Rph20 Oxford S MR Rph3 Rph20, Rph24 Granger MSS R Rph3+ Rph20 Design your fungicide strategy to address the disease risk and the resistance ranking of your variety

5 What is Adult Plant Resistance (APR) provided by one or more minor genes (eg. Rph20) partial or slow-rusting resistance so plants can still have rust provides protection in post-seedling stages seedlings can still be susceptible plants can still benefit from fungicide protection APR expression can vary depending on Disease pressure (less effective when too high) Temperature (less effective when too cold for expression) Crop health and nutrition

6 Fungicide response in APR varieties Comparing Untreated control to single early spray to double spray 2013 earlier disease onset 2014 later disease onset Trials conducted by: Kithsiri Jayasena (DAFWA, Albany) Under low disease pressure, APR provides enough control, under high disease pressure APR requires fungicide support

7 Seed and in-furrow fungicides

8 Seed dressing and in-furrow fungicides for barley. Spot type net blotch (STNB) and other diseases. New products registered in barley provide different options for disease control systemic protection from establishment may replace need for one or more foliar spray particularly strong for necrotrophic diseases (STNB, NTNB, Scald) may not be as long lasting for rusts / mildew Seed dressing: Systiva (fluxapyroxad) In-furrow: Uniform (azoxystrobin + metalaxyl-m)

9 Spot type net blotch trial results: Susceptible varieties sown onto infected stubble, responses in five trials at: Merredin (2), Arthur River, Gibson, Grasspatch Yield response to: Systiva or Uniform plus foliar application ranged from 0-16%. Systiva seed treatment alone ranged from 0-15%. Multiple spray applications ranged from 0-24% Responses in the majority of trials were less than 10%. Greatest responses occurred when yields were more than 3t/ha. Foliar fungicide applied before stem extension need follow up application for continued disease control and yield response.

10 Yield response in high yielding site Esperance 2015 STNB severity and yield of STNB infected barley (LaTrobe & Hindmarsh) under different fungicide regimes (Gibson 2015) Yield (t/ha) Yield LSD = 0.24 STNB severity STNB severity (%LAA top 3 leaves) 2 Nil Systiva (SD) Systiva+Z41 Z31 + Z41 Fungicide treatment Data: Andrea Hills (DAFWA) 0

11 Spectrum of disease control

12 Spectrum and duration of disease control from seed dressings Litmus barley, Inoculated nurseries, DAFWA South Perth Fungicide Rate % Leaf area affected (average top 4 leaves) Tillering Flowering - grain fill PM NTNB NTNB STNB Scald BLR NIL Baytan T 150ml Jockey Stayer 300ml Systiva 150ml < P <0.001 <0.001 <0.001 < LSD

13 Key messages Variety selection will influence what diseases are prominent in your paddock and in your region Varieties with Adult Plant Resistance (APR) to leaf rust will have less rust but can respond to fungicide New registered seed dressing and in-furrow fungicides provide good protection from early disease onset, particularly for blotch diseases Know the fungicide group and active ingredient of seed or in-furrow fungicides and alternate foliar products away from these groups Manage the green bridge to reduce rust risk

14 Acknowledgements: DAFWA research support units at Esperance, Geraldton, Wongan Hills, Katanning and Merredin DAFWA and growers for trials. Companies (BASF, Bayer, Four farmers, Syngenta) for product treatments. DAFWA and GRDC (DAW00229) for funding. Contact: Geoff Thomas Plant Pathologist, South Perth Department of Agriculture and Food, Western Australia Web: Kithsiri Jayasena Plant Pathologist, Albany Department of Agriculture and Food, Western Australia #protectwacrops.

15 Barley diseases current variety status Powdery mildew Currently of lesser importance Improvement in variety resistance reduces overall pressure Net type net blotch Stubble borne disease Changing virulence on varieties such as Oxford Spot type net blotch Stubble borne disease Nearly all varieties susceptible Leaf rust Major gene resistance not effective (eg. Bass) Rely on minor gene resistance for reduced impact

16 NTNB virulence can change Variety Beecher Attacking Beecher Non- Attacking Skiff pathotype Less dominant isolate from WA Dominant Isolate from WA South Stirlings (2014) Pompadour Maritime Beecher Grimmett Dampier Hindmarsh Bass Commander Oxford