Yield Impacts and Management Strategies for Wheat Diseases that Fungicides Don t Control (BYD and BLS) Dr. Madeleine Smith and Dr.

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1 Yield Impacts and Management Strategies for Wheat Diseases that Fungicides Don t Control (BYD and BLS) Dr. Madeleine Smith and Dr. Ruth Dill-Macky

2 Wheat Pathology Collaboration - BLS

3 Bacterial Leaf Streak

4 Bacterial Leaf Streak Xanthomonas translucens pv. undulosa

5 Importance of BLS-Impact on Yields: 2013 Blade RB07 Knudson Yield (% of non-inoculated control) y = x R² = y = x R² = y = x R² = BLS (% flag leaf infected)

6 Yield losses can be significant Demonstrated losses of up to 40% in hard red spring wheat cultivars under significant disease pressure

7 Survival BLS Epidemics seed - but a very low transmission rate soil - survival is poor, better when crop debris is present weeds - broad host range, survives epiphytically Conditions favoring epidemics BLS appears to be promoted by warm temperatures wet leaves from dew and rain facilitate infection micro-injuries to leaf surfaces aid infection Spread rain, dew, plant-to-plant contact, epiphytic phase

8 BLS Epidemiology Factors contributing to the increase in BLS? susceptible wheat varieties reduced tillage practices (debris and weeds) warmer temperatures changes in the pathogen population other leaf diseases fungicides

9 Effect of Fungicides on BLS? BLS reduces yield significantly Prosaro - and likely all other fungicides - have little or no impact on BLS Widespread use of fungicides may be revealing BLS cooperative with Blake Cooper - Limagrain Cereal Seeds

10 BLS severity is affected by isolate and host origin Disease Severity (square root of lesion length) severity on barley severity on wheat CIX96 CIX29 CIX34 CIX27 CIX28 CIX77 CIX32 CIX95 CIX82 CIX22 CIX85 CIX26 CIX79 CIX21 CIX45 CIX46 CIX25 CIX94 CIX90 CIX30 CIX52 CIX87 CIX93 CIX83 CIX20 CIX81 CIX67 CIX41 CIX78 CIX75 CIX84 CIX43 CIX92 CIX132 CIX76 CIX86 buffer CIX69 CIX112 CIX73 CIX110 CIX111 CIX71 CIX74 CIX72 CIX51 CIX59 CIX104 CIX89 CIX108 CIX103 CIX36 CIX62 CIX97 CIX63 CIX105 CIX61 CIX49 CIX130 CIX106 CIX37 CIX58 CIX31 CIX101 CIX53 CIX54 CIX64 CIX129 CIX65 CIX55 CIX35 CIX38 CIX88 CIX39 CIX23 CIX40 CIX47 CIX48 CIX24 CIX66 CIX107 CIX57 CIX127 CIX42 CIX128 CIX109 CIX125 CIX50 CIX68 CIX91 CIX33 CIX44 CIX126 CIX60 CIX56 CIX131 CIX isolates from barley 9 Isolates from 52 isolates from wheat other sources

11 Host Resistance Cooperative Nurseries inoculated fungicide treated small plots In 2013 and 2014 we ran cooperative nurseries testing lines from six HRSW breeding programs in the Upper Great Plains

12 BLS Cooperative Nursery Responses are somewhat variable - multiple sites are valuable BLS distribution within plots is variable Resistance is not complete no immunity

13 BLS Cooperative Nursery Responses are somewhat variable - multiple sites are valuable Late lines may be escaping disease Resistance is not complete no immunity

14 BLS Cooperative Nursery Responses are somewhat variable - multiple sites are valuable Late lines may be escaping disease Resistance is not complete no immunity

15 Inoculation Methods

16 Inoculation Methods

17 Inoculation Methods

18 Take Home Messages Fungicides do not appear to have any impact on BLS fungicides have no activity on bacterial pathogens fungicides may have helped to reveal BLS infections Host resistance available - selection of cultivars avoid planting susceptible cultivars Brennan, Samson, Select, SY-Soren, WB-Mayville some cultivars have resistance SY Rowyn, Prevail, Focus, Forefront Avoid using highly infected seed

19 Barley Yellow Dwarf (BYD)

20 BYDV- symptoms Symptoms can very in appearance and severity depending on crop, time of infection and variety When plants get infected early, around the five leaf stage, severe stunting occurs Leaves become chlorotic and may turn red to purple from the tip down, particularly in oats Photo: Keith Weller, USDA Photo: Carl Bradley, University of Illinois

21 Barley yellow dwarf (BYD) Caused by the Barley yellow dwarf virus (BYDV) Different strains of BYDV:PAV,PAS,MAV,SGV, RPV,RMV and GPV (RPV+RMV = CYDV) Infects wheat, barley and oats

22 BYDV-vectors 20 aphid species: Bird cherry oat (Rhopalosiphum padi), English grain (Sitobion avenae) and being the most common in MN These aphid species differ in their efficiency of transmitting different strains of BYDV Erin Hodgson, Iowa State University

23 Methodology Collect symptomatic plants from around the state (2013, 2014, 2015) Harvest total RNA Using RT-PCR methods for strain detection

24 M +ve RT-PCR for Strain Differentiation -ve B I and II I and II: B/CYDVs subgroups I (~830 bp) and II (~370 bp) 1.5 kb 1.2 kb kb bp 800 bp 700 bp 600 bp 500 bp 400 bp 300 bp 200 bp Basic multiplex (two fragment system), the first primer set differentiates B/CYDVs subgroups I and II Subgroup I: BYDV- PAV, BYDV-MAV, BYDV-SGV Subgroup II: CYDV-RPV and BYDV-RMV Enhanced multiplex (four fragment system), differentiates subgroup I and II members 100 bp

25 Preliminary Results Although PAV and MAV thought to be most common, now detecting some CYDV

26 BLS BYD Next Steps Complete optimization of inoculation methods Continue to use screening methods to evaluate regional breeding material Evaluate grass isolates for pathogenicity on wheat and barley and as a reservoir for disease Complete molecular strain characterization from MN and SD Asses grass species as a reservoir for BYD Start evaluating host resistance and vector control

27 Questions? Please contact me at: