Late season disease control : cluster rots & downy mildew Wayne Wilcox & Alice Wise Cornell Univ & Cornell Coop Ext.- Suffolk County With thanks to Wendy McFadden-Smith and Turner Sutton
Heavy rains/tropical storms postverasion make late season disease management tough 2011 TS Irene Aug. 28 2.3 pelting rain second half of the storm wind only (salt) TS Lee Sept. 6-8 3 over 3 days 2012 Labor Day deluge 2 rain + 2 d. cloudy, damp weather TS Sandy Superstorm harvest over some trellis damage, big decrease in TR business
ROTS!
BOTRYTIS BUNCH ROT: 2-cent REVIEW OF BIOLOGY Primary infections of Botrytis occur during/soon after flowering, remain latent
BOTRYTIS BUNCH ROT: 2-cent REVIEW OF BIOLOGY Latent infections can become active usu. postveraison/pre-harvest Other yeasts, fungi, bacteria join the party = bunch rot Turner Sutton : > 70 species fungi, bacteria Pre-veraison Botrytis infections occur in some seasons (2012)
FACTORS THAT INCREASE LATENT INFECTION ACTIVATION Atmospheric/microclimate humidity Plant water status Berry nitrogen content Injury (wounding) GBM, birds etc
BOTRYTIS BUNCH ROT: 2-cent REVIEW OF BIOLOGY Significant losses are due to pre-harvest spread, both berry-to-berry touch & spores thru wounds (rain cracking, insects, birds etc.)
Canopy management effects on botrytis Vignoles ± shoot thinning ± rachis removal Modified VSP High wire
NEW PRODUCT: BOTECTOR Yeast-like fungus (A. pullulans), mfr. claims works via competition for colonization sites Hence = protective only Label specifies not to apply w/ other chemicals 10 oz/a, up to 3 apps./yr 4 hr REI, 0 day PHI Good results in WFW 2012 trial (first look)
Bitter rot, white cv. Can occur w/ripe rot Bitter rot black sporulation, more distinct conc. circles Ripe rot salmon colored sporulation
Bitter rot, red cv. Bitter rot raisined berries stay soft -- handling can make hands sooty Black rot raisined berries turn hard -- handling no sooty residue
BITTER ROT: DISEASE CYCLE Overwinters in fallen leaves, berries; cold-damaged shoot tips; dead bark of 1-yr canes During growing season, gelatinous masses of spores produced, splash-dispersed (short distances) to green parts of vine Infection if tissues remain wet long enough, dep. on temp (72-77 F optimum, 6-12 hr wetness) TS : infection as early as bloom, starts on pedicels
BITTER ROT: DISEASE CYCLE Infections of pedicels, fruit remain latent until ripening Warm + wet weather activates infections In LI research vineyard, most problematic variety has been Chardonnay.
BITTER ROT: CONTROL Sanitation Remove overwintering inoculum sources (mummified fruit, pedicels, other dead tissues) Somewhat less disease w/cane- vs. spur pruning Alternate hosts? Fungicides 2-wk intervals bloom thru harvest during rainy periods where a problem LI bitter rot w/ 2 app s of captan or Pristine included in pre-veraison spray schedule See Wayne s annual disease mgt overview for update
BITTER ROT: FUNGICIDES (Turner Sutton ratings) Mancozeb (66 PHI) ++++ Strobies (all), Captan, Topsin +++ DMI ++ Copper + Vangard, Scala, Elevate, Rovral 0
SOUR ROT Imprecise, colloquial term often used as a catch-all for non-botrytis rots occurring pre- / at harvest Secondary invaders of wounds (birds, insects, rain cracking, mechanical, powdery mildew, Botrytis) Various fungi (incl. yeasts), bacteria
TRUE SOUR ROT Colonization by acetic acid forming bacteria (Acetobacter, Gluconobacter) -- Vinegar smell Sour rot - Riesling
TRUE SOUR ROT Bacterial infection frequently followed by infection/colonization by several wild yeasts (Hanseniaspora uvarum = Kloeckera apiculata most common) -- Ethyl acetate (nail polish remover) aroma -- The last few years on LI, fruit flies often seem to accompany sour rot
True sour rot, cv. Riesling Botrytis (sporulation) Sour rot (no sporulation)
True sour rot, cv. Pinot noir
SOUR ROT DEVELOPMENT Infection can occur on visibly-wounded cheeks or at apparently intact juncture of berry & its stem (pedicel) Microscopic mechanical injuries due to pulling away as berries swell and compact? Vinegar fly egg laying?
SOUR ROT DEVELOPMENT Typically following rains Distribution of bacteria Berry swelling, thus cracking & separation from pedicel LI 2012 Labor Day rainy period Most severe under warm conditions Ideal = high 70 s
SOUR ROT DEVELOPMENT In Ontario, no disease detected in field until berries reached 15 Brix Confirmed by lab inoculations of berries at different Brix levels Causal microorganisms not isolated from berries until after disease was observed Needle in a haystack or just not there?
SOUR ROT DEVELOPMENT In recent study from Portugal, causal organisms of sour rot isolated from vinegar flies -- AND, no sour rot on clusters protected from flies by fine netting, even when injured Do vinegar flies (and SWD?) carry organisms to berries, larvae from eggs at berry/pedicel juncture enter at fine wounds and inoculate?
SOUR ROT CONTROL: THEORETICAL PRINCIPLES Minimize injuries birds, insects Minimize spread Minimize pathogen populations Provide berry microclimate less conducive to pathogen growth
SOUR ROT CONTROL: RESEARCH from ONTARIO Goal: loosen clusters 20 ppm GA, prohexidione-ca (Apogee) at highest rate consistently loosened clusters in Riesling and Pinot noir, reduced sour rot only in Riesling Return-bloom issues with GA Apogee not labeled on grapes (nor being developed for such?)
SOUR ROT CONTROL: RESEARCH from ONTARIO Post-veraison applications of Oxidate, copper, Serenade, Pristine, vermicompost, Milstop, Raingard and potassium meta-bisulphite (KMS) at 2 lb/100 gal did not reduce sour rot Calcium chloride treatments initiated at pea-size berry did not reduce sour rot LI anecdotal Oxidate may help a little but $$$
SOUR ROT CONTROL: RESEARCH from ONTARIO KMS at 4 lb/100 gal and 8 lb/100 gal reduced the severity of sour rot when applied from veraison through harvest -- KMS not labeled for vineyard applications Results from initiating KMS applications at different pre-harvest intervals did not provide insight into the optimum timing for starting such treatments
SOUR ROT CONTROL: Registered Options Worth a(nother) Look? Post-veraison coppers -- Anti-bacterial -- Controls DM (favored by same conditions) -- Winemaking problems? Drosophila (vinegar flies, SWD) controls
Drosophila (SWD) control Product Active ingredient Preharvest interval Comments Delegate Spinetoram 7 days No more than 2 consecutive app s Entrust SC Spinosad 7 ditto Triple Crown Bifenthrin Imidacloprid Zeta-cypermethrin 30 RUP Danitol Fenpropathrin 21 RUP Malathion (several formulations) malathion 3 Information from Greg Loeb, entomologist, NYSAES Look for an update in Greg s 2013 annual overview
Vineyard management to reduce cluster rots Appropriate canopy density Cluster zone leaf removal postbloom Cluster thin space out clusters Do not overuse water and nitrogen
Vineyard management techniques Control injuries to berries to reduce cluster rots -- PM infections early diffuse infections may predispose berries -- Birds, GBM etc. -- Bees, wasps etc are problematic Loosen clusters to reduce berry to berry spread -- Ontario work with GA; Apogee not labeled -- Cluster zone leaf removal early bloom to reduce set -- Kelp products cluster stretching - efficacy?
6 basal leaves removed early bloom 2010 Chardonnay
Early July 2010 Early bloom leafing - Reduced cluster compactness - Clusters had more sunburn - No rot that harvest Late July 2010
Look for updates on cluster rots in Wayne s 2013 disease control overview
Late season downy mildew
Not a late season issue but downy mildew on clusters has become much more common in recent years
Downy mildew on upper surface of grapevine leaf.
Downy mildew Spreads rapidly on lvs. Can defoliate vines No leaves = no ripening winter hardiness
2011 Phos acid + copper not enough under heavy pressure
Hybrid and American varieties are less susceptible to DM than vinifera Arandell
Control of downy mildew Chardonnay Oct. 12, 2012 (post harvest) Presidio 3.5 oz + Manzate 2.5 lbs. 6-26 Presidio, 3.5 oz + Captan, 2.5 lbs. 7-16, 8-16 Ranman, 2.5 oz 6-26, 7-16, 8-16 Revus, 8 oz 6-26, 7-16, 8-16 Manzate ProStick, 2.5 lbs., 6-26 Captan 50W, 2.5 lbs., 7-16, 8-16 Incidence Severity 1.35 b 0.26 b 5.31 ab 0.06 b 5.94 ab 0.04 b 20.73 a 3.03 a Gavel restricted use, 66 DTH Reason not labeled for use on LI Ridomil groundwater issue
Late season downy mildew options Preharvest interval Comments Mancozeb 66 Days to harvest a limitation Gavel 66 Restricted use pesticide in NY Ranman* 30 Tank mix w/phos acid gives excellent control Reason* 30 RUP in NY; not labeled for LI; strobie connection Presidio* 21 RUP in NY; absorbed; tank mix w/protectant Pristine* 14 Efficacy under pressure? Phyto w/some var s Abound, Quadris Top* 14 Azoxystrobin + difenoconazole; phyto on apples Revus 14 Absorbed, not subject to wash off Sovran & Flint 14 Strobies, weaker on DM Captan 0 48 hr reentry interval Phos acid products 0 Efficacy under pressure? Copper 0 Limited app s, winemaking issues? * Resistance risk is high
Good DM control essential post-veraison Canopy management Over the row net top of canopy problematic lots of lateral shoots hard to get with sprayer Hard to keep vineyard 100% clean