Update 8 – May 31, 2020

UW-Plant Pathology & UW-Madison Division of Extension are very pleased to announce that Dr. Leslie Holland will be starting her new post as an assistant professor and extension specialist in Fruit Pathology on August 17, 2020. While this is the Vegetable Crop Updates Newsletter, many of our readers also raise fruit crops. Dr. Holland holds a PhD in Plant Pathology from the Univ. of California, Davis, and has >6 years of experience with fungal canker pathogens of perennial fruit crops. She graduated with a MS in Plant Pathology from Washington State Univ. and earned her BS in Biology at New Mexico State Univ. She is an Ohio native and is excited to be back in the Midwest. Holland enjoys cooking, hiking, fitness, and teaching her puppy, Clyde, new tricks! She is very excited to join Plant Pathology and the UW Fruit Team, and eager to serve as a researcher, educator, and advocate for students, fruit growers, and supporting industries in WI. Dr. Holland will be a likely contributor to the WI Fruit News newsletter.


Amanda Gevens, Dept. Chair, Associate Professor & Extension Specialist, UW-Madison Plant Pathology, gevens@wisc.edu, Cell: 608-575-3029. https://vegpath.plantpath.wisc.edu/

Current P-Day (Early Blight) and Disease Severity Value (Late Blight) Accumulations. (Many thanks to Ben Bradford, UW-Madison Entomology; Stephen Jordan, UW-Madison Plant Pathology). A P-Day value of ≥300 indicates the threshold for early blight risk and triggers preventative fungicide application. A DSV of ≥18 indicates the threshold for late blight risk and triggers preventative fungicide application. Red text in table indicates threshold has been met/surpassed. TBD indicates that data is To Be Determined as time progresses. Weather data used in these calculations comes from weather stations that are placed in potato fields in each of the four locations. Data are available in graphical and raw data formats for each weather station at: https://vegpath.plantpath.wisc.edu/dsv/

Location Planting Date 50% Emergence Date Disease Severity Values 5/30/20 Potato Physiological Days 5/30/20
Grand Marsh Early Apr 17 May 18 3 (5/27) 68.9 (5/27)
Mid Apr 25 May 26 0 (5/27) 13.5 (5/27)
Late May 6 TBD TBD TBD
Hancock Early Apr 8 May 18 5 95.9
Mid Apr 20 May 25 3 45
Late May 4 May 30 0 7.42
Plover Early Apr 10 May 23 6 61.1
Mid Apr 20 May 30 0 6.84
Late May 5 TBD TBD TBD
Antigo Early May 14 TBD TBD TBD
Station set up at airport 5/29 Mid May 24 TBD TBD TBD
Late Jun 1 TBD TBD TBD


Special Fungicide Registrations for WI: Several chlorothalonil products have 24(C) Special Local Need Registrations for extended active ingredient use on potatoes for late blight, early blight, black dot, and Botrytis. Bravo Ultrex, Bravo WeatherStik, and Bravo ZN have special registrations through 2022. Echo 720, Echo 90DF, and Echo ZN will expire in December of 2020 – however the process to extend this special registration beyond 2020 has begun with Sipcam Agro; I provided a letter of support to this application back in April. Omega 500F (fluazinam) has special registration for in-furrow application for the management of powdery scab of potato. This registration will expire in December of 2020.


2020 University of Wisconsin Madison Extension Commercial Vegetable Crop Production Management Guide: Our production guide is updated every October with release of a new guide in January. The book can be downloaded for free as a pdf at the link below, or can be purchased online for $12.50. https://learningstore.extension.wisc.edu/products/commercial-vegetable-production-in-wisconsin


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