Chris Smart Plant Pathology and Plant-
Microbe Biology Cornell University
Geneva, NY
Review of 2013 Vine Crop Diseases
Powdery Mildew Podosphaera xanthii
• VERY common – we see it every year
• Some varieties have resistance
• Kills leaves – Sun scald
• Weakens handles in pumpkins
• More susceptible to some other diseases
Powdery Mildew
• Evidence that the pathogen can overcome some plant resistance – This is still the way to go!
• That the pathogen can overcome some fungicides
• Effective fungicides (conventional and organic) are available
Virus Diseases
• Watermelon Mosaic – present every year, arrives later in the season
• Cucumber Mosaic –not here every year or in every field, arrives early
• Aphid transmitted • Post bloom – only foliar
symptoms • Pre-bloom – fruit
symptoms Photo: Marc Fuchs
Symptoms • First symptom is a
yellowing spot on the upper surface of the leaf
• Spots expand turning tan and papery, but are bordered by veins
• Lower leaf surface has gray spores
Downy Control • The pathogen blows in either from the south,
or from greenhouse production around lakes Erie and Ontario, and generally does not arrive until late July or August – In Eastern NY, inoculum could come from either
source, and usually arrives later in the season • No commercially available resistant cucurbits
– but I am working with several breeders and we have high hopes!
• Vegetable news letters provide information on where downy has been reported
• Excellent website http://cdm.ipmpipe.org/ – Sign up for alerts
Downy Control
• The downy mildew pathogen is closely related to Phytophthora (both are water molds), many fungicides that are effective against downy are also labeled for Phytophthora blight – Many water-mold specific fungicides – Broad-spectrum protectant fungicides provide
some control • Follow outbreaks and know when the
pathogen is in the area
Phytophthora Blight
• Over winters as thick-walled spores in the soil
• Small white spores produced during the growing season, can’t survive over winter
• Swimming spores also produced
How Does Phytophthora Move?
• Culled fruit • Cultivation • Soil (tractor tires) • Rain
water/splashing • Irrigation water • Flood water • Does not move in
air/wind
Surface Irrigation Water • 60% of NY vegetables are irrigated with
surface irrigation water • Surveyed 20 sites across NY for
Phytophthora capsici once a month for 2 years – pathogen can be present in water
• Improving detection methods to identify pathogens quickly
• Comparing methods for decontamination
Blight Farm
• Five faculty now have P. capsici projects • Testing different varieties for resistance • Testing integrated control strategies • Ways to improve soil health – cover crops • Pathogen detection • Four 2-acre blocks, one block is organic
Management Strategies
• If you don’t have Phytophthora blight – KEEP IT OFF YOUR FARM!
• If you have Phytophthora blight – Promote good drainage – Choose tolerant varieties – Rotate – Rogue if possible – Use effective fungicides (ROTATE
CHEMISTRIES)
Management Strategies
• Commonly used fungicides – Ranman – Presidio (18-month plant-back restriction) – Gavel – Forum – Revus – Tanos – Phosphorous acid fungicides – Ridomil (perhaps once/season in Western NY)
Thanks! • Smart lab members • Grower cooperators • Vegetable Extension
Educators • NYS Ag Expt Station • NYS Dept of Ag and
Mkts • USDA - NIFA