Vineyard IPM Scouting Report for week of 21 May 2012 UW-Extension Door County and Peninsular Agricultural Research Station Sturgeon Bay, WI

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1 NO. 6 1 Vineyard IPM Scouting Report for week of 21 May 2012 UW-Extension Door County and Peninsular Agricultural Research Station Sturgeon Bay, WI Comparison of powdery and downy mildew Powdery mildew Downy mildew Site of infection Environmental conditions for infection (A) Both sides of leaf (B) Grows on leaf surface (A) High humidity but moisture such as rainfall detrimental to spores (B) Optimal (68 to 77 F) but ranges (59 to 90 F) (C) Low diffuse light conditions favor development (A) Only infects bottom of leaf (B) Grows inside of leaf (A) High humidity and free moisture in the form of rainfall or dew needed for infection (B) Optimal (64 to 76 F) but ranges (54 to 86 F) Tissue infected (A) All green tissue (B) Berries susceptible until 3 to 4 weeks post bloom (C) Leaves and green tissue susceptible throughout season Spore transmission Wind Splashing water Symptoms Potential problem periods Highly susceptible grape varieties Management Cultural Essential Management Period Management challenges (A) Circular spots that are not limited by leaf veins (B) Advanced infections will cover leaves with thick web of spores, leaves turn yellow and may fall off (C) Spores produced in a single chain on a single stalk Dry periods during the growing season Leon Millot, Seyval, Vignoles (A) Reduce shading in canopy by; 1) shoot positioning and 2) leaf removal (A) Angular spots that are limited by leaf veins (B) Grey/white fuzz on undersides of leaf, top of leaf has yellow blotches that look oily (C) Spores produced singly on end of branched stalks Wet periods during the growing season La Crescent (A) Reduce tissue wet period by: 1) site selection, 2) vine spacing, 3) control tall weeds, 4) shoot positioning, and 5) leaf removal (B) Sanitation remove fallen leaves and fruit from vineyard Start of bloom to 4 weeks post bloom. Use the best fungicides within your budget for immediate pre-bloom to post bloom Alternate strobilurins (Abound, Sovran, Flint) with other chemistries from spray to spray or tank mix with sulfur. Follow a similar strategy with the sterol inhibitors Endura and Quintec. Only use strobilurins two times during the season. Note: Flint has poor efficacy on downy mildew.

2 Comparison of powdery and downy mildew 2 Powdery Mildew Powdery Mildew Powdery Mildew White patches of powdery mildew on top of leaf White patches of powdery mildew on top of leaf. Notice patches not limited by leaf veins Conidiophore of powdery mildew. Notice single stalk compared to downy mildew Early symptoms of downy mildew yellow oily spots Later symptoms of downy mildew top of leaf Grey/white fuzz of downy mildew on bottom of leaf Sporangiophore of downy mildew Photo credit The University of Georgia, College of Agriculture and Environmental Sciences Downy Mildew Downy Mildew Downy Mildew

3 Development of wine grapes in the grape variety trials at the Peninsular Agricultural Research Station (PARS) Sturgeon Bay, WI and West Madison Agricultural Research Station (WMARS), Madison, WI 3 Brianna at PARS Brianna at WMARS Foch at PARS Foch at WMARS Frontenac at PARS Frontenac at WMARS

4 4 Development of wine grapes in the grape variety trials at the Peninsular Agricultural Research Station (PARS) Sturgeon Bay, WI and West Madison Agricultural Research Station (WMARS), Madison, WI La Crescent at PARS La Crescent at WMARS La Crosse at PARS La Crosse at WMARS inch shoots Marquette at PARS Marquette at at WMARS PARS inch shoots

5 5 Development of wine grapes in the grape variety trials at the Peninsular Agricultural Research Station (PARS) Sturgeon Bay, WI. NY 76 at PARS Vignoles at PARS Petite Pearl at PARS Two year old vines Noiret at PARS Leon Millot at PARS Wild grapes at PARS

6 6 Development of wine grapes in the grape variety trials at the Spooner Agricultural Research Station (SARS) Spooner, WI. Grapes Can Survive in Spooner, WI Brianna SARS Marquette SARS What s lurking in or near the vineyard this week? Grape Plume Moth larvae, Geina persicelidactylus (Fitch) (Lepidoptera:Pterophoridae) on wild grapes at PARS on The Grape plume is not a problem in commercial vineyards. A telltale sign of the grape plume moth larvae are leaves tied together with silken strands. The larvae feeds within the folded leaf. Full-grown larva are 5/8 inches long, yellow/green with white hairs. Typically populations never build large enough to warrant control measures.

7 7 Degree Day 1 (base 50) Accumulation from April 1 to May 20, 2012 at Peninsular Agricultural Research Station in Sturgeon Bay, WI Date Year Average 2 4/1 to 5/ Modified method. 2 Average from 2007 to Degree Day 1 (base 50) Accumulation from April 1 to May 20, 2012 at West Madison Date Year Average 2 4/1 to 5/ Modified method. 2 Average from 2007 to Accumulated degree days 1 (base 50) for the month of March in Sturgeon Bay and Madison, WI. Year Madison WI Sturgeon Bay WI Modified method. 2 Data from GDD (base 50, ceiling 86) Please scout your vineyards on a regularly scheduled basis in an effort to manage problem pests. This report contains information on scouting reports from specific locations and may not reflect pest problems in your vineyard. If you would like more information on IPM in grapes, please contact Dean Volenberg at (920) or dean.volenberg@ces.uwex.edu