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Grape Powdery Mildew - BCWGC Powdery Mildew _Field Day 2016.pdf • Powdery mildews are usually very host specific • Requires living tissue to grow • Colonizes the surface of plant

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Text of Grape Powdery Mildew - BCWGC Powdery Mildew _Field Day 2016.pdf • Powdery mildews are usually...

  • Grape Powdery Mildew Dan O’Gorman: Agriculture and Agri-Food Canada,

    Summerland Research and Development Centre (SuRDC)

  • • Biology

    • Symptoms

    • Disease Cycle

    • Weather condition

    • Control

    Grape Powdery Mildew

    P. Sholberg

  • • Most common and easily recognized plant diseases

    • Powdery mildews are usually very host specific

    • Requires living tissue to grow

    • Colonizes the surface of plant tissue and invade top layers of epidermis cells

    • Powdery mildews cause extensive losses in plant growth and crop yield

    Grape Powdery Mildew

  • Two stages to powdery mildew infections: Primary and Secondary infections

    Grape Powdery Mildew

    https://www.agric.wa.gov.au/spring/powdery- mildew-grapevines-western-australia?page=0%2C2

    https://www.agric.wa.gov.au/spring/powdery- mildew-grapevines-western-australia?page=0%2C2

    P. Sholberg

    P. Sholberg

    Primary infection: caused by ascospores released in spring by overwintering structures called cleistothecia

    Secondary infection: caused by conidia spores which can infect, develop new conidia and re-infect in a continuous cycle through the summer

    Secondary infection cycles approx. every 5 to 30 days depending on the weather

  • Cleistothecia

    Photo: Peter Sholberg AAFC

    Photo: Peter Sholberg AAFC

    Genera of Powdery Mildew Fungi (Drawing by C.B. Kenaga, E.B. Williams, and R.J. Green)

  • • Powdery Mildew infection (primary and secondary)

    • Haustoria are specialized hyphae for nutrient absorption from the plant cells. • The plant is damaged by the loss of nutrients to the fungus, disruption of photosynthesis, and premature death of leaves or other infected plant tissues

    https://www.agric.wa.gov.au/spring/powdery-mildew-grapevines-western- australia?page=0%2C2

  • Symptoms

    • Observed in all “succulent parts” of the grapevine

    Peter Sholberg AAFC

    • Symptoms can also be observed in late-summer, fall and winter as dark blotchy areas on dormant canes

    http://seresinestate.blogspot.ca/2010_10_01 _archive.html

    Peter Sholberg AAFC

  • Symptoms

    • Powdery mildew affects fruit causing russeting, splitting and rotting

    Peter Sholberg AAFC Peter. Sholberg, AAFC

  • Ascospores will colonize any fresh green tissue

    Grape Powdery Mildew - Primary Infection (spring)

    First signs of the disease can be observed after bud- break (early spring).

    http://seresinestate.blogspot.ca/2010_10_01_archive.html

  • Grape Powdery Mildew- Secondary Infections (summer)

    Peter Sholberg, AAFC

  • Mildew Disease Cycle Primary infection

    period

    Secondary Infection period Grapevine powdery mildew life cycle. Drawing by R. Sticht. Reproduced with permission from Compendium of Grape Diseases, 1988, American Phytopathological Society, St. Paul, MN. USA.

  • Effect of Temperature on the Development of Grape Powdery Mildew

    Temperature of leaf*

    ( o C)

    Days for spores to develop and infect vine parts and

    produce new spores

    6 32

    9 25

    12 18

    15 11

    17 7

    23 6

    26 5

    30 6

    33 o C for at least 3 days X - but 10% of spores can

    recover in 5 days

    40.5 o C for at least 6 hrs X - kills the fungus

    • Primary infection in the spring requires leaf wetness and temperature

    • Secondary infection in mid/late season does not require free moisture BC Ministry of Agriculture (http://www.agf.gov.bc.ca/cropprot/grapeipm)

    20-30°C Optimum

    > 33°C Stops germination

    > 40°C Spores die

    Secondary Infection

    > 10°C 12-15 hrs continuous wetness

    Primary Infection

    temp & rain

    http://www.agf.gov.bc.ca/cropprot/grapeipm http://www.agf.gov.bc.ca/cropprot/grapeipm

  • Okanagan Weather 2016

    Primary infection in the spring requires leaf wetness and temperature

    1. Ascospores are released in the spring after a rainfall of at least 2.5 mm

    2. Infection requires at least 12-15 hours of continuous wetness at 10-15 °C

    > 10°C 12-15 hrs continuous wetness

    0

    10

    20

    30

    40

    50

    60

    70

    80

    March April May June July

    ave (⁰C)

    rain (mm)

    https://weather.gc.ca/city/pages/bc-84_metric_e.html

    Primary Infection

    temp & rain

  • Okanagan Weather: March 2016

    0

    2

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    18

    20

    1 2 3 4 5 6 7 8

    Mean Temp Definition °C

    Total Rain Definition mm

    0

    2

    4

    6

    8

    10

    12

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    18

    20

    1 2 3 4 5 6 7 8

    Mean Temp Definition °C

    Total Rain Definition mm

    > 10°C 12-15 hrs continuous wetness

    http://climate.weather.gc.ca/climate_data/generate_chart_e.html

    Primary Infection

    temp & rain

  • Okanagan Weather: April 2016

    > 10°C 12-15 hrs continuous wetness

    http://climate.weather.gc.ca/climate_data/generate_chart_e.html

    Primary Infection

    temp & rain

  • Okanagan Weather: May 2016

    0

    2

    4

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    1 2 3 4 5 6 7

    Mean Temp Definition °C

    Total Rain Definition mm

    > 10°C 12-15 hrs continuous wetness

    Primary Infection

    temp & rain

    http://climate.weather.gc.ca/climate_data/generate_chart_e.html

  • Okanagan Weather 2016

    Secondary infection in mid/late season does not require free moisture

    • 20-29°C – optimum fungal growth (infection cycle ~5-6 days) • > 33°C –(3 days) stops spore germination (~10% of spores can recover) • > 40°C – (for at least 6 hrs) fungus is killed

    Secondary Infection

    20-30°C Optimum

    > 33°C Stops germination

    > 40°C Spores die

    0

    5

    10

    15

    20

    25

    30

    35

    40

    March April May June July

    high (⁰C)

    ave (⁰C)

    http://climate.weather.gc.ca/climate_data/generate_chart_e.html

  • Disease Management

    Cultural Control

    • Remove lateral shoots in dense canopies/remove leaves in fruit zone: low light intensity favours powdery mildew development.

    • Use drip or micro-jet irrigation system

    • Control vigour: excessive vigour can lead to higher disease pressure

    • Variety selection: select varieties that are less susceptible to

    mildew

  • Susceptibility of Grape Cultivars to Powdery Mildew

    Susceptible Intermediate Least Susceptible

    Bacchus Cabernet Franc

    Cabernet Sauvignon Chancellor Chardonnay Chasselas

    Gamay Gewurztraminer

    Grenache Himrod

    Madeleine Angevine Madeleine Sylvaner

    Malbec Petit Verdot Rkatzeteli

    Riesling Sauvignon blanc

    Schonburger Siegerebe

    Syrah Viognier

    Chelois Chenin Blanc

    Concord Foch

    Pinot blanc Malbec Merlot Ortega

    Pinot Noir Perlett

    Sheridan Vidal Blanc

    Weissburgunder

    Auxerrois Malvoisie

    Melon Pinot Gris Semillon

    BC Ministry of Agriculture (http://www.agf.gov.bc.ca/cropprot/grapeipm)

  • Chemical control

    • Sulfur can be used exclusively, or in combination with DMI, strobilurin, or other classes of chemicals

    • Alternate between different fungicide groups to avoid fungicide resistance problems

    • Products like summer oils have also been shown to be good at suppressing mildew

    Disease Management

    ://www.pinterest.com/anteekvintage/farm-collectibles/& http://ernestartist.org/June17_2011_02.htm

    https://www.google.ca/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwj4w7SV_ajOAhUmxoMKHaUVCgMQjRwIBw&url=https://www.pinterest.com/anteekvintage/farm-collectibles/&bvm=bv.128987424,d.amc&psig=AFQjCNEKZ6-ZiUcXps9gVPcqJJspoJyRbQ&ust=1470441847897199 https://www.google.ca/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwj4w7SV_ajOAhUmxoMKHaUVCgMQjRwIBw&url=https://www.pinterest.com/anteekvintage/farm-collectibles/&bvm=bv.128987424,d.amc&psig=AFQjCNEKZ6-ZiUcXps9gVPcqJJspoJyRbQ&ust=1470441847897199 https://www.google.ca/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwj4w7SV_ajOAhUmxoMKHaUVCgMQjRwIBw&url=https://www.pinterest.com/anteekvintage/farm-collectibles/&bvm=bv.128987424,d.amc&psig=AFQjCNEKZ6-ZiUcXps9gVPcqJJspoJyRbQ&ust=1470441847897199 https://www.google.ca/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uac

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