Powdery Mildew and Bunch Rot: A Different Perspective

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1 Powdery Mildew and Bunch Rot: A Different Perspective Wayne F. Wilcox Department of Plant Pathology Cornell University New York State Agricultural Experiment Station Geneva, NY 14456

2 Powdery mildew

3 POWDERY MILDEW: EFFECT of TEMPERATURE on DISEASE SPREAD Temp, F Generation time (days) not active 95 lethal

4 POWDERY MILDEW: OTHER ENVIRONMENTAL EFFECTS ν Atmospheric humidity υ Disease often most severe near bodies of water, other vineyard sections subject to high humidity

5 Carroll, J.E. & Wilcox, W.F. Phytopathology 93: (2003).

6 POWDERY MILDEW: OTHER ENVIRONMENTAL EFFECTS ν Light Exposure υ Disease more severe where shaded ΦPoorly quantified, little formal examination

7 POWDERY MILDEW: EFFECT OF SUN EXPOSURE (cv. Chancellor; Geneva, NY 2005) ν Vines covered with: υ 1 layer of shade cloth ΦAdmitted 35% of available solar radiation υ 2 layers of shade cloth ΦAdmitted 20% of available solar radiation

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10 Chardonnay, 4 light levels: (a, b) tree shade, inner or outer canopy; (c, d) clearing, inner or outer canopy

11 Severity of Powdery Mildew on Foliage of cv. Chardonnay Vines Subjected to Different Forms of Natural Shade Leaf Area Diseased (%) Clearing, Exposed Tree, Exposed Clearing, Canopy Tree, Canopy

12 ENVIRONMENTAL EFFECTS: SUN-EXPOSED vs. SHADED ν Air temperature-- --No difference ν Relative humidity-- --No difference

13 ENVIRONMENTAL EFFECTS: SUN-EXPOSED vs. SHADED ν ν Air temperature-- --No difference Relative humidity-- --No difference ν Leaf temperature 2 to 23 F higher for sun-exposed vs. shaded

14 ENVIRONMENTAL EFFECTS: ν ν SUN-EXPOSED vs. SHADED Air temperature-- --No difference Relative humidity-- --No difference ν Leaf temperature 2 to 23 F higher for sun-exposed Φ Fungal development: = optimum; 90 = maximum; >95 = lethal

15 ENVIRONMENTAL EFFECTS: SUN-EXPOSED vs. SHADED ν UV-B B Radiation υ Single shade cloth % of exposed υ Double shade cloth-- --8% of exposed υ Inner canopy, no trees-- --8% of exposed υ Inner canopy, trees-- --2% of exposed

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18 Light, no UV Double shade

19 50 Severity of Powdery Mildew on Foliage Subjected to Different Light Treatments (cv.. Chancellor; Geneva, NY 2006) Leaf Area Diseased (%) No Shade No UV Double Shade

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22 POWDERY MILDEW CONTROL: EFFECT OF CARRYOVER INOCULUM (Chardonnay, Geneva ) Sept April 2003 Foliar PM Cleistothecia % Severity per kg/bark 1 1, , ,700 *Sprays applied immediate prebloom through fruit set only

23 POWDERY MILDEW CONTROL: EFFECT OF CARRYOVER INOCULUM (Chardonnay, Geneva ) Sept April 2003 Sept Foliar PM Cleistothecia Cluster PM % Severity per kg/bark % Severity* 1 1, , , *Sprays applied immediate prebloom through fruit set only

24 POWDERY MILDEW PERIOD OF HOST SUSCEPTIBILITY

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28 YMA LYS YMC MLB Lactic acid bacteria Brettanomyces non-saccharomyces yeasts Lodi-Clean Lodi-DI All yeasts Fig. 2. Microflora of Pinot Noir berries from Lodi, NY without diffuse powdery mildew. Fruit were harveste lots of 100 berries per treatment were plated on 4 se media. Heights of bars indicate the number of colon units per 100 ul sample, and represent the following yeasts; LYS = non-saccharomyces yeast s, presum Kloeckera; YMC = Brettanomyces and Dekkera yeas = lactic acid bacteria. Total microflora can be estima combining counts from YMA and MLB.

29 POWDERY MILDEW FUNGICIDES

30 POWDERY MILDEW FUNGICIDES: SULFUR ν ADVANTAGES υ Inexpensive υ Effective υ No resistance concerns

31 ν POWDERY MILDEW FUNGICIDES: ADVANTAGES υ Inexpensive υ Effective υ No resistance ν HOWEVER SULFUR υ Many of its specific activities are assumed,, on the basis of few or no data

32 SULFUR ACTIVITY: PROTECTIVE & CURATIVE ASSAYS in greenhouse ν Riesling seedlings in greenhouse ν Sprayed with micronized sulfur (Microthiol, 5 lb/a) υ 3-14 days before inoculation (protective) υ 1-10 days after inoculation (curative)

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35 POWDERY MILDEW FUNGICIDES: STEROL INHIBITORS (DMI ν ADVANTAGES SUBGROUP) υ Very effective at low use rates υ Locally systemic (rainfast) υ Protective (limited) + post-infection activities υ Relatively long application intervals

36 POWDERY MILDEW FUNGICIDES: STEROL INHIBITORS (DMIs) ν DISADVANTAGE υ Resistance is widespread in USA, Europe Φ Recent reports from Chile, Australia υ Still provide control, but not as effective as in past

37 FUNGICIDE (PESTICIDE) ν Results from the RESISTANCE υ SELECTION υ of INDIVIDUALS υ in a POPULATION

38 Qualitative (All or nothing) Quantitative (Shades of gray) (Benomyl, Ridomil, QoI) (DMI, dodine)

39 Distribution of Sensitivities to Myclobutanil,1995 vs % Frequency of isolates 40% 30% 20% 10% '99 DMI-R 0% '95 DMI-R '99 Baseline '95 Baseline Log ED (μg/ml) myclobuta

40 EFFECT OF RATE ON POWDERY MILDEW CONTROL: DMI-RESISTANT VINEYARD POPULATION (cv. Seyval, Finger Lakes, NY) %Disease control, fungus type Treatment, rate/a All Untreated (68% cluster area infected) Rally, 4 oz Rally, 2 oz wk 2 intervals

41 EFFECT OF RATE ON POWDERY MILDEW CONTROL: DMI-RESISTANT VINEYARD POPULATION (cv. Seyval, Finger Lakes, NY) %Disease control, fungus type Treatment, rate/a All Susceptible Untreated (68% cluster area infected) Rally, 4 oz Rally, 2 oz wk 2 intervals

42 EFFECT OF RATE ON POWDERY MILDEW CONTROL: DMI-RESISTANT VINEYARD POPULATION (cv. Seyval, Finger Lakes, NY) %Disease control, fungus type Treatment, rate/a All Susceptible Resistant Untreated (68% cluster area infected) Rally, 4 oz Rally, 2 oz wk 2 intervals

43 DMI RESISTANCE MANAGEMENT RECOMMENDATIONS ν ν ν ν Maximum of 3 applications per year Tank mix w/sulfur (inexpensive) Rotate with effective unrelated materials Utilize full recommended rates, provide excellent spray coverage υ Fungus responds to rate on the vine,, not in the tank!

44 POWDERY MILDEW FUNGICIDES: STROBILURINS (QoIs) ν Abound, Sovran, Flint, Pristine ν Most important group of new fungicides since DMIs ν Relatively broad spectrum, v. good to exc. against PM

45 POWDERY MILDEW FUNGICIDES: STROBILURINS (QoI) ν RESISTANCE RISK IS VERY HIGH υ Multiple powdery mildew failures in NY beginning 2002

46 STROBILURIN (QoI) RESISTANCE IN NEW YORK ν In 2002, serious PM cluster infections appeared suddenly in treated vineyards, at multiple commercial sites υ Extremely susceptible varieties (Chardonnay( Chardonnay) υ Total applications since registration

47 STROBILURIN (QoI) RESISTANCE IN NEW YORK ν In 2002, serious Uncinula cluster infections appeared suddenly in treated vineyards, at multiple commercial sites in NY υ Extremely susceptible varieties (Chardonnay( Chardonnay) υ Total applications since registration υ Not all users had problems Φ Few problems for those who had regularly tank-mixed w/sulfur

48 POWDERY MILDEWCONTROL, 2002 (cv. CHARDONNAY, FINGER LAKES, NY) Treatment, rate/a None... Standard*... Pristine, 8.4 oz.... % PM, Cluster area 80 a 51 b 9 c... 9 c *Rubigan/ 2 Abound/ Rubigan/Abound/ 2 sulfur **Pyraclostrobin (QoI) + boscalid (carboxyanilide( carboxyanilide)

49 POWDERY MILDEWCONTROL, 2002 (cv. CHARDONNAY, FINGER LAKES) Treatment, rate /A % PM, Cluster area None a Standard* b Pristine, 8.4 oz c strobie component, 5.4 oz b boscalid component, 3.0 oz. 3 c *Rubigan/ 2 Abound/ Rubigan/Abound/ 2 sulfur **Pyraclostrobin (QoI)) + boscalid (carboxyanilide)

50 RATE EFFECT?

51 POWDERY MILDEWCONTROL, 2003: cv. CHARDONNAY, FINGER LAKES PM, % area Treatment, rate/a Cluster None BAS 500 (Pyraclostrobin), 3.9 oz BAS 500 (Pyraclostrobin), 5.4 oz BAS 500 (Pyraclostrobin), 6.8 oz wk 2 intervals, 6 Jun - 27 Aug

52 Pyraclostrobin, max rate

53 POWDERY MILDEW FUNGICIDES: ALTERNATIVE PRODUCTS ν Primarily contact action, body of PM fungus is on outside of plant υ Oils υ Potassium salts (Armicarb, Kaligreen, Mycostop,, Nutrol) υ Hydrogen peroxide (Oxidate)

54 POWDERY MILDEW FUNGICIDES: ALTERNATIVE PRODUCTS ν Short-term term knock-down,, relatively little to no residual activity υ Stylet Oil has some; salts, Oxidate don t ν Complete coverage is imperative

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56 % Leaf Area Infected 100 Protectant Assay of MKP Trial 1 - Severity p= Post-Spray Inoculation Day Water MKP MKP Spray Before Inoculation Protectant Assay of MKP Trial 2 - Severity % Leaf Area Infected Post-Spray Inoculation Day Water MKP

57 12000 Post-Infection Assay of MKP Trial 1 - Sporulation Conidia/cm 2 Leaf p=.002 p=.003 p< Post-Inoculation Spray Day Water MKP MKP Spray After Inoculation Post-Infection Assay of MKP Trial 2 - Sporulation Conidia/cm 2 Leaf p<.001 p=.009 p=.02 p<.001 Water MKP Post-Inoculation Spray Day

58 Effect of MKP (Nutrol) Spray Concentration an Frequency on Powdery Mildew Severity % Leaf Area Infected % 39% 65% % Check 1% Nutro 0.5% Nutr Year cv. Rosette grapevines; Ge WF Wilcox and DG Riegel

59 POWDERY MILDEWCONTROL, 2003: cv. ROSETTE, GENEVA (6 2-wk) PM, % area Treatment, rate/a Leaf Cluster None Kaligreen,, lb* Nutrol, 4-8 lb (+ surfactant)** Rubigan/2 Pristine/2 Microthiol *Approx. $20 - $40/A per application **Approx. $4 - $8/A per application

60 POWDERY MILDEWCONTROL, 2005: cv. ROSETTE, GENEVA (9 10-d intervals) PM, % area Treatment, rate/a Leaf Cluster None Kaligreen,, lb Nutrol, 5-10 lb (+ surfactant) Microthiol,, 5 lb Rubigan/2 Pristine/2 Microthiol.* *14-day intervals

61 POWDERY MILDEWCONTROL, 2006: cv. ROSETTE, GENEVA (8 10-d intervals) PM, % area Treatment, rate/a Leaf Cluster None Nutrol Elite/2 Pristine/ 5 Nutrol <1 2 Rubigan/2 Pristine/2 Microthiol*.. 11 <1 *14-day intervals

62 SPECIFIC FUNGICIDES & GROUPS: ν Oils TOPICAL PM MATERIALS υ Highly-refined petroleum oils Φ JMS Stylet Oil, PureSpray (Petro Canada) υ Botanicals Φ Neem oil, others υ Excellent eradicative activity if coverage υ Protective activity?

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65 BIOFUNGICIDE : SERENADE ν Fermentation product of a soil-borne bacterium (Bacillus( subtilis) υ Bacterial metabolites υ Bacterial spores ν No residue issues, minimal REI (4 hr)

66 BIOFUNGICIDE : SONATA ν Fermentation product of a soil-borne bacterium (Bacillus( pumilis) υ Bacterial metabolites υ Bacterial spores ν No residue issues, minimal REI (4 hr)

67 POWDERY MILDEWCONTROL, 2006: cv. ROSETTE, GENEVA (8 10-d) PM, % area Treatment, rate/a Cluster Leaf None Serenade Elite/ 2 Pristine/ 5 Serenade Rubigan/ 2 Pristine/ 2 Microthiol* <1 11 * 14-day intervals

68 POWDERY MILDEWCONTROL, 2006: cv. ROSETTE, GENEVA (8 10-d) PM, % area Treatment, rate/a Cluster Leaf None Sonata Elite/ 2 Pristine/ 5 Sonata Rubigan/ 2 Pristine/ 2 Microthiol* <1 11 * 14-day intervals

69 Botrytis Bunch Rot--B. cinerea

70 BOTRYTIS BUNCH ROT: CONSIDERATIONS ν Botrytis fungus is a weak pathogen, prefers: υ Injured tissues Φ Berry moth, birds Φ Cracking Φ Powdery mildew

71 BOTRYTIS BUNCH ROT: CONSIDERATIONS ν Botrytis fungus is a weak pathogen, prefers: υ Injured tissues Φ Insects, cracking, PM υ Senescent ( downhill( downhill ) ) tissues Φ Old blossom parts Φ Ripening fruit

72 BOTRYTIS BUNCH ROT: CONSIDERATIONS ν Infection can occur: υ Bloom thru bunch closing ΦUsually remain latent (dormant) until ripening

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75 BOTRYTIS BUNCH ROT: CONSIDERATIONS ν Infection can occur: υ Bloom thru bunch closing υ Veraison thru harvest

76 BOTRYTIS BUNCH ROT: CONSIDERATIONS ν Infection can occur: υ Bloom thru bunch closing υ Veraison thru harvest ν BUT, when is infection most likely or most damaging? υ When are sprays most necessary?

77 Botrytis on Pinot Noir: Time of Infection, Cluster Tightness Effects ν Three "clones" υ 29 (tight clusters) υ Mariafeld (loose clusters) υ 29, thinned to resemble Mariafeld

78 Botrytis on Pinot Noir: Time of Infection, Cluster Tightness Effects ν Three "clones" υ 29 (tight clusters) υ Mariafeld (loose clusters) υ 29, thinned to resemble Mariafeld ν Inoculate at four developmental stages υ Late bloom υ Pea-size υ Bunch close υ Veraison

79 INFECTION TIMING/ CLUSTER ARCHITECTURE: CONCLUSIONS ν Most early infections (bloom-bc) remain latent, never become active and rot berries ν BUT, activated latent infections are potentially important for initial disease establishment and source of rapid disease spread as berries become highly susceptible after veraison

80 DISEASE SPREAD EXPERIMENTS ν Inoculated 0, 1, 3, or 5 berries/cluster at 10 days after veraison υ Provided point sources for spread ΦSimulated limited activation of a few latent infections initiated at bloom

81 2 Spread Expt. Inoculations

82 EFFECT of CLUSTER TIGHTNESS on DISEASE SPREAD (Pinot noir 29; Geneva, NY; 2002) Unthinned Thinned Berries per Cluster Inoculated

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84 BOTRYTIS BUNCH ROT ν Infection can occur: υ Bloom, post-bloom periods ΦUsually remain latent until ripening Factors that activate latent infections are poorly understood

85 ACTIVATION OF LATENT INFECTIONS: ATMOSPHERIC HUMIDITY ν Inoculated potted Chardonnay vines at bloom ν Maintained outdoors, covered ν Imposed 95% RH for 0-9 days at: υ Veraison υ 10 days preharvest

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87 ACTIVATIONS OF LATENT INFECTIONS: PLANT WATER STATUS ν Potted Chardonnay vines ν Inoculated at late bloom, maintained outdoors in screenhouse ν Watered regularly until veraison, then: υ Watered often to keep soil wet (WET) OR υ Watered only when shoot tips stated to wilt (DRY)

88 ν ν ACTIVATIONS OF LATENT INFECTIONS: PLANT WATER STATUS Potted Chardonnay vines, inoculated at late bloom, maintained in screenhouse Watered regularly until veraison, then: υ υ Watered to keep soil wet (WET), or Watered only when shoot tips stated to wilt (DRY) ν Disease incidence evaluated υ Harvest υ Post-harvest incubation (4 >90% RH)

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90 BOTRYTIS EPIDEMIOLOGY: PREHARVEST RAIN EFFECTS (Working model) ν High RH activates latent infections υ Direct effect on fungus or host-plant interaction? (Plant water status?) ν High soil moisture activates latent infections υ Plant water status? ν Free water promotes de novo infections by conidia, secondary spread

91 BOTRYTIS BUNCH ROT: ν Fungicides υ When? MANAGEMENT ΦProtect against early latent infections? ΦAgainst new infections and 2 2 spread post-veraison veraison? ΦBoth?

92 BOTRYTIS BUNCH ROT: ν Fungicides υ When? MANAGEMENT Φ Protect against early latent infections? Φ Against de novo infections and 2 2 spread post-veraison veraison? Φ Both? υ Answer depends on climate (geographical and seasonal variations)

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94 BOTRYTIS FUNGICIDES Material Post-inf inf? Other Vangard Yes Consistently our top Scala Yes Sim.. (+/-) ) to Vangard Elevate Yes (!) Good rotational Pristine Some Higher rate (19 oz/a), PM, other bunch rots Flint Little Higher rate (3 oz/a), PM, other bunch rots Rovral Yes Resistance where history

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