SPUDS, SOYBEANS, SUNFLOWERS, SOIL-BORNE DISEASES AND STUDENTS - - PowerPoint PPT Presentation

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SPUDS, SOYBEANS, SUNFLOWERS, SOIL-BORNE DISEASES AND STUDENTS - - PowerPoint PPT Presentation

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SPUDS, SOYBEANS, SUNFLOWERS, SOIL-BORNE DISEASES AND STUDENTS Jacquie van der Waals Department of Plant Sciences University of Pretoria Plant Sciences Seminar Feb 2015 What I say is that, if a fellow really likes potatoes, he must be a

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SPUDS, SOYBEANS, SUNFLOWERS, SOIL-BORNE DISEASES… AND STUDENTS

Jacquie van der Waals Department of Plant Sciences University of Pretoria

Plant Sciences Seminar Feb 2015

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“What I say is that, if a fellow really likes potatoes, he must be a pretty decent sort of fellow”

(AA Milne, 1882 – 1956)

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Foliar diseases

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Wilts

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Tuber diseases

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Foliar diseases

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BROWN SPOT (MALROES)

"There are no foolish questions and no man becomes a fool until he has stopped asking questions." Charles P. Steinmetz

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  • Reduced sensitivity to azoxystrobin found in field isolates (Mr Joel Dube

MSc 2014)

  • van der Waals et al., 2011
  • Dube et al., 2014

Brown spot – Alternaria alternata

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Management of brown spot

  • Mr Newman Nyoni MSc
  • Development of management strategy for brown spot of potatoes
  • Fungicide spray programmes
  • Effect of N nutrition
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Wilts

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SOFT ROT AND BLACKLEG

“Concern for man and his fate must always form the chief interest of all technical endeavours. Never forget this in the midst of your diagrams and equations.” Albert Einstein

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Soft rot and blackleg

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No Pectobacterium wasabiae or Dickeya solani found (Ngadze et al., 2012) 2010: FIRST REPORT of Pectobacterium carotovoum

  • subsp. brasiliense in South

Africa – most important pathogen in SA No Pectobacterium atrosepticum

  • r Dickeya solani found

(Van der Merwe et al., 2010)

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Soft rot / blackleg cont.

  • Role of phenolic compounds in disease resistance

(Ngadze et al., 2012)

  • Effect of calcium soil amendments in disease resistance

(Ngadze et al., 2014)

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Soft rot / blackleg cont.

  • Effect of temperature on growth of Pectobacterium and

Dickeya spp. in vitro (Susan du Raan, MSc 2015)

Species Optimal Temperature Temperature Growth Range

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Implications?

Climate change = 2oC

(van der Waals et al., 2013)

Temperature = Disease

Species shift

Pa, Pw Pcb, Pcc Dd, Ds

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BACTERIAL WILT

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Characterisation of bacterial diseases of potato in Nigeria

Vou Shutt Moses PhD

  • i. Survey of bacterial diseases of potato in Nigeria
  • ii. Isolate and identify bacteria
  • iii. Determination of genetic diversity of strains (Ralstonia

solanacearum, Pectobacterium spp. and Dickeya spp.)

  • iv. Study response of different potato varieties in Nigeria to

these bacteria

  • F. Niederwieser
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Tuber diseases

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SOIL-BORNE DISEASES

Powdery scab, common scab, black scurf, silver scurf, black dot, dry rot

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POWDERY SCAB

“Confidence is the feeling you sometimes have before you fully understand the situation.” Unknown

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POWDERY SCAB

  • Most devastating and economically important disease in many potato

growing regions of the world

  • Integrated management of disease
  • Detection and eradication of pathogen in contaminated tunnels (Wright

et al., 2012)

  • Soil amendments: chemicals and biological control agents
  • Cultivar susceptibility screening
  • Development of bio-assay for on-farm testing of soils (“grower friendly”)
  • Best crops to plant in rotation programmes with potatoes
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Powdery scab management

Cultivar susceptibility screening

  • Pot trials
  • Field trials
  • Phenolic content

Kennedy Simango PhD Genetic diversity of Spongospora subterranea f.sp. subterranea Kennedy Simango PhD Jessica Wright MSc 2013 Development of bioassays Chris Slabbert MSc Determination of host range of pathogen Kennedy Simango PhD Chris Slabbert MSc Effect of soil amendments

  • n disease development

Kennedy Simango PhD Role of soil temperature and moisture in infection process Chris Slabbert MSc Survival in soil (long-term study)

NOTE: PhD / Post-doc positions available on this project

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RHIZOCTONIA RESEARCH

"Discovery consists of seeing what everybody has seen and thinking what nobody has thought." Albert von Szent-Gyorgy

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Rhizoctoniasis

(A. Pitman, New Zealand)

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Mr Norman Muzhinji PhD

  • A survey of anastomosis groups and genetic diversity of

Rhizoctonia solani on potatoes in SA

  • AG 3 was shown to cause elephant hide on potatoes in South

Africa; Binucleate Rhizoctonia stem canker (Muzhinji et al., 2014a,b)

  • Effect of inoculum source on disease development
  • Population structure of Rhizoctonia solani AG 3-PT field

populations revealed by microsatellite markers

  • Screening of Rhizoctonia solani isolates to various fungicides

Characterisation and symptomatology of Rhizoctonia solani associated with potato diseases in South Africa

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ATYPICAL TUBER BLEMISHES

“If we knew what it was we were doing, it would not be called research, would it?” Albert Einstein

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Wooley et al., 2011

Spatial and temporal changes in the structure of microbial communities of the potato rhizosphere and the possible effects thereof on development of atypical tuber blemishes (Josephine Zimudzi, PhD)

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CROP ROTATION

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Root associated micro-organisms and their role in crop production in a region-specific crop rotation program for the Eastern Free State

Mr Joel Dube PhD

  • Use of metagenomic methods to investigate the role of

root associated microorganisms in crop productivity

  • Main crop: potatoes; Rotation crops: maize, sugar beans,

sunflower and soybean

  • Monitor microbial populations associated with rhizosphere

and rhizoplane over full annual cropping cycles

  • Identification of microorganisms that are key members of

these two zones

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SUNFLOWERS AND SOYBEANS

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Etiology and population structure of Macrophomina phaseolina (charcoal rot) on sunflower and soybean in South Africa

Mrs Estiene Jordaan PhD

  • Development of a pathogenicity

screening assay for soybean and sunflower

  • Determine diversity of M.

phaseolina isolates from various crops (in particular sunflower and soybean) in South Africa

  • Role of various factors such as

temperature, preceding crop and pH on growth rate of isolates

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Final year BSc Agric students

  • Mr Steve Nel
  • Biocontrol of charcoal rot of soybean caused by Macrophomina

phaseolina

  • Mr Sepeke Ratau
  • Evaluation of fungicides for control or inhibition of

Sclerotinia sclerotiorum soybean isolates in vitro

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Acknowledgements

  • Funding bodies:
  • Potatoes South Africa
  • Protein Research Foundation
  • NRF
  • THRIP
  • Commercial growers (field trials)
  • AgChem Companies (field trials)
  • Seed companies (field trials
  • Collaborators / Co-supervisors:
  • Prof Teresa Coutinho
  • Dr Linus Franke (UOFS)
  • Dr Anton Haverkort (Plant Research Int’l, Wageningen)
  • Prof Nico Labuschagne
  • Prof Martin Steyn
  • Dr Mariette Truter (ARC)
  • Dr Leah Tsror (Volcani Institute, Israel)
  • Dr James Woodhall (Fera, UK)
  • Ms Lindie Erasmus
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