Color Me Pink, Seed Treatments in Wheat - Dr. Madeleine Smith Best of the Best 2015

Color Me Pink, Seed
Treatments in Wheat
   Dr. Madeleine Smith
   Best of the Best 2015

Root Rots – A Complex of Diseases

• Common Root Rot (CRR) – Bipolaris sorokiniana
• Crown Rot (FCR) – Fusarium spp.
• Take-all – Gaeumannomyces graminis var. tritici
• Other root diseases
  • Sharp Eyespot – Rhizoctonia ceralis
  • Snow Rot – Pythium spp.
  • Snow Mold – Fusarium nivale & Typhula spp.
  • Strawbreaker foot rot – Tapezia yallundae

Common Root Rot - CRR

• Common Root Rot – Bipolaris sorokiniana
• Symptoms
  • brown lesions on roots & SCI
  • dark brown discoloration
     of crown & stem bases
  • reduced tillering
  • smaller heads
                                   Photo: Don Mathre, Montana State University

Crown Rot - FCR
• Crown Rot – Fusarium spp.
• Symptoms
  • dark brown lesions
     at basal node
  • pink discoloration
     of crown & stem bases
  • death of infected tillers
  • white heads
                                Photo: Nigel Cattlin

Take-All

• Take-all Gaeumannomyces graminis var. tritici
• Symptoms
  • shiny black roots,
     crowns & stem bases
  • plants easily pulled
     from the soil
  • dead plants in patches

                             Photo: ,wwww.wa.gov.au

Root Rots: A Complex of Diseases

• Common Root Rot & Crown Rot
  • present every year – losses likely average 3-5%
  • severe disease possible - 40% losses have been
    reported

• Take-All
  • likely less damaging than CRR and CR

• ALL root diseases will adversely impact plants
  under moisture stress

Root Rot Survey Work

2013/14 – Root Rot Survey
         Minnesota

Preliminary Findings of Field Surveys

•   Root diseases were more common than expected –
    we observed symptoms in most fields.

•   Crown Rot (Fusarium spp.) appears to be more
    prevalent than expected compared to Common
    Root Rot.

•   This represents a change from older surveys.

Seed Treatment Trials

Seed Treatments
          for CRR and CR-control
• A number of seed treatments are marketed for
  control of these disease and to help stand
  establishment.

• These are unlikely to provide long term benefits to
  mature plants.

• There is a lack of data on best practice.

Trial Set-up
• Four on-farm locations throughout MN
  2013/14

• One location in Langdon, ND for 2014

• Randomized complete block design with four
  replications for each treatment at each site

• Planted the root –rot susceptible cultivar
  Oxen

Trial Set-up
•   Stand counts were made at the two
    leaf stage to determine stand
    establishment.

•   Plants were assessed at Feeke’s
    Growth Stage 10 for appearance of
    white heads not due to insect
    damage.

•   Plant height was measured at
    heading.

•   Biomass was measured at harvest.

•   10 plants collected for isolation of
    fungi per plot.

Seed Treatments
Treatment                Active ingredients                            g a.i./lb
Control                  untreated
Charter HL               triticonazole                                 0.023
Stamina                  pyrachlostrobin                               0.022
Stamina F3               pyrachlostrobin + triticonazole + metalaxyl   0.022 + 0.022 + 0.013
Dyna Shield              metalaxyl                                     0.063
Dyna Shield (reduced)    metalaxyl (half rate)                         0.01
Raxil MD                 tebuconazole + metalaxyl                      0.007 + 0.009
Raxil MD Extra           Imazalil + tebuconazole + metalayxl           0.015 + 0.006 + 0.009
Tebuconazole             tebuconazole                                  0.007
Vibrance Extreme         Sedaxane + difenaconazole + mefenoxam         0.010 + 0.049 + 0.012
Vibrance                 sedaxane                                      0.011
Systiva                  fluxapyroxad                                  0.022
Evergol Energy (2014)    prothiolconazole + penflufen + metalaxyl      0.023 + 0.012 + 0.272

Results-MN
•   In 2013, no significant differences were detected in stand counts, plant
    heights, biomass or yield.

•   In 2014, no differences were detected or yield either between
    treatments or compared to the untreated control, except in the trials
    near Fergus Falls and Benson.

•   In Fergus Falls trial tebuconazole reduced grain yield compared to the
    untreated control (p=0.005).

•   In the trial near Benson Raxil MD increased yield compared to the
    untreated control (P=0.015).

•   This increase in grain yield was likely the result of a higher initial stand
    observed with Raxil MD when compared to the control (P= 0.014).

Results-ND
• In 2014 trials were conducted in
  Langdon with all 13 treatments.

• Although some white heads were
  observed in plots, there were no
  statistical differences for stand,
  yield or biomass between the
  seed treatments and the
  untreated control.

Conclusions
• The preliminary results from this study suggest that seed
  treatments will not always be necessary for stand protection.

    – In only 1 out of 8 environments across the past two years did
      one of the seed treatments result in a better initial stand
      compared to the untreated control.

• Preliminary data from the fungal isolations from mature crowns
  and roots show that several fungal species, including Fusarium
  spp., can frequently be isolated.

• The decision to use a seed treatment will continue to be a based
  on the condition of the seed lot; whether loose smut or other
  seed born disease require control and/or the field history.

Conclusions
• These data suggest that seed treatments are not efficacious
  throughout the whole growing season.

• Being able to control and/or reduce infections past the window
  of efficacy of the seed treatments is important in years when
  plants are at risk of drought stress.

• These infected root systems are compromised and are less
  efficient at taking up water and nutrients.

• Genetic resistance to crown and root rot may provide better all-
  round disease control with less economic risk compared to a
  seed treatment.

Root Rot Research – Next Steps
•   Fungal isolations will be completed to determine if there is any difference in fungal
    populations between treatments.

•   Establish techniques to screen for genetic resistance to root and crown rots in breeding
    material.

•   Initial work has conducted in 2014 field trials suggests that producing good disease pressure
    for crown rot is possible in a field situation. This work will continue in 2015.

•   In the disease nurseries soil temperatures and other environmental conditions will be
    monitored to allow correlation with disease development.

Acknowledgements

                                         •   Amar Elakkad
    •   Shaobin Zhong                    •   Beheshteh Zagaran
    •   Pravin Gautam                    •   Jochum Wiersma
                                         •   Doug Holen
                                         •   Eric Koeritz
                                         •   Peter Samuels
    •   Shaukat Ali
                                         •   Samuel Haugen
                                         •   Rafael Cunha
                                         •   Julia Hagenguth
                                         •   Irakli Koclamazashvili
Minnesota Association of Wheat Growers   •   Jillian Reilly
and Minnesota Wheat Council              •   Rebekka Schneider

Questions?

Please contact me at:

smit7273@umn.edu