Integrated Disease Management Based on Cultivar Susceptibility and Fungicide Sensitivity

Integrated Disease Management Based on Cultivar Susceptibility and Fungicide Sensitivity Patricia McManus, Victoria Kartanos, Matt Stasiak University of Wisconsin-Madison & UW-Extension January 10, 2017

Copper Highly effective on downy mildew Limited activity against other pathogens Sulfur Highly effective on powdery mildew Little or no activity on other pathogens

Lots of Unknowns for Cold Climate Varieties Cultivar BR DM PM Phom. Anthr. S Cu Brianna? +????? Edelweiss??????? Maréchal Foch ++ + ++ + ++ Yes Yes Frontenac +++ + ++ + + No? Frontenac gris ++ + ++ + + No? La Crescent ++ +++ ++ +++ +?? La Crosse +++ ++ ++ ++ +?? Marquette +++ + +???? St. Croix? ++ ++ +++ +?? Degree of susceptibility/sensitivity: + = slightly; ++ = moderately; +++ = highly;? = not known

Each cultivar tested in 5 to 11 independent trials, 2012-2015 Brianna Frontenac Frontenac gris La Crescent LaCrosse Léon Millot Maréchal Foch Marquette NY76 St. Croix Valiant

Copper injury on Brianna

Sensitivity to Copper Do not apply copper to Brianna Restrict copper to 1 or 2 sprays/season, avoiding consecutive sprays, on Frontenac, Frontenac gris, LaCrescent, Léon Millot, Maréchal Foch, Marquette, and St. Croix

Sulfur injury on Maréchal Foch

Sensitivity to Sulfur Do not apply sulfur to Maréchal Foch, Léon Millot, or Brianna Restrict sulfur to 1 or 2 sprays/season on La Crescent and St. Croix

Copper and Sulfur in Spray Programs Initial Considerations Do you have reason to use copper and/or sulfur? Organic Fungicide resistance management Economics Are copper and sulfur compatible with other products you rely on? Copper or sulfur applied alone in our trials no adjuvants, no tank mixes Read labels carefully

Copper Incompatibility Copper fungicides should not be mixed with phosphorous acid fungicides or any product that will reduce ph below 6.5 At lower ph, copper ions released from fixed fungicides more quickly Because some forms of copper are persistent, consider the interval between copper and phosphorous acid sprays

Copper and Sulfur in Spray Programs Weather at time of application and within 24 hours after Hot temps (> 85 F) increases risk of sulfur injury Cool temps, prolonged wetness increase risk of copper injury

Applying the Knowledge Possible spray programs not yet tested Focus on DM, PM, and BR Additional attention in early season where Phomopsis and/or anthracnose are a problem 2017 Midwest Fruit Pest Management Guide Organic Production and IPM Guide for Grapes, T. Weigle and J. Carroll, Cornell Cooperative Extension

Susceptible Resistant Downy mildew Powdery mildew Black rot Valiant, LaCrosse La Crescent Brianna, Frontenac, Frontenac gris Valiant, Marquette St. Croix Marquette Frontenac, Frontenac gris Brianna La Crosse La Crosse Frontenac, Frontenac gris Marquette St. Croix La Crescent, Valiant Brianna, St. Croix La Crescent

Possible Organic Program for La Crescent Growth stage Dormant Bud break thru pre-bloom Fungicides Lime sulfur or liquid sulfur if history of Phomopsis or anthracnose Fixed copper for DM* (and Phomopsis) Bloom thru 4 wk post-bloom Thru harvest Fixed copper for DM* Organic options (e.g., Serenade) for Botrytis based on scouting and weather Sulfur for PM based on scouting *If more than 2 copper sprays needed, apply under dry conditions

Possible Reduced-Risk Program for La Crescent Growth stage Dormant Bud break thru pre-bloom Bloom thru 4 wk post-bloom Thru harvest Fungicides Lime sulfur or liquid sulfur if history of Phomopsis or anthracnose Phosphorous acid for DM (rather than captan or mancozeb) Phosphorous acid for DM alternated with strobilurin (e.g., Abound, Pristine, Flint) for multiple diseases Sulfur or strobilurin for PM based on scouting

Removal of black rot mummies from the ground and especially the trellis before bud break is essential! Rain Spores Bruce Watt photo

Possible Marquette Reduced-Risk Program Growth stage Dormant Bud break up to pre-bloom Pre-bloom thru 4 wk post-bloom Thru harvest Fungicides Lime sulfur or liquid sulfur if history of Phomopsis or anthracnose Phosphorous acid OR fixed copper for DM based on scouting and weather DMI (e.g., Rally, Vintage) alternated with strobilurin (e.g., Abound, Pristine, Flint) for BR, PM, and other diseases Sulfur for PM based on scouting

Copper and Sulfur in Spray Programs Further considerations Do you need post-infection activity? Copper is strictly protective, no post-infection activity Sulfur is primarily protective, but good post-infection control up until time that PM growth appears Other fungicides provide better post-infection activity against DM and PM

Thank You! Questions?