Sustainable Ag Expo, Monterey, CA Doug Gubler, Department of Plant Pathology, University of California, Davis

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1 Sustainable Ag Expo, Monterey, CA Doug Gubler, Department of Plant Pathology, University of California, Davis Modern Day Fungal Management Powdery Mildew Botrytis bunch rot Canker Diseases

2 Pathogen Biology: Why important? What drives the pathogen? Reproduction Sporulation Overwintering

3 Disease Epidemiology: What drives the epidemic? Temperature Leaf Wetness Temperature X Leaf Wetness RH Sunlight Exposure Wind Speed

4 Botrytis cinerea BOTRYTIS BUNCH ROT

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13 Disease Triangle-Epidemiology Pathogen Requires free water for spore germination. Requires free water for infection. Requires >95% RH for sporulation. Movement from berry to berry (nesting) Environmental Conditions Temps between 5-85 F. Optimum temperature is 65 F. Host Variable susceptibility Time Leaf wetness duration X temperature

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15 Effect of canopy management and fungicide applications on botrytis bunch rot in Chenin blanc, Napa County TIMING OF FUNGICIDE APP. Bloom+ Control Bloom Preclose Preclose Mean Incidence (% diseased clusters) Leaf Removal No removal Mean NS Severity (% rot per cluster) Leaf Removal No removal Mean NS Yield (tons per acre) Leaf Removal NS No removal Bettiga, Gubler, Marois, Bledsoe. California Agriculture, 1989

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18 Grape Botrytis Bunch Rot Severity Doug Gubler, Carneros, CA. 211 Final Results Incognito.8lb 16 **Inspire Super 2oz 28 **Vangard 1oz 29 **Sw itch 14oz 3.5 Elevate 1lb 12 *Pristine 23 oz fb. Vangard 1oz fb. Pristine 23oz fb Elevate 16oz 13 *Pristine 23oz fb. Elevate 1lb fb Pristine 23oz fb Vangard 1oz 29 Untreated Botrytis Bunch Rot Severity (%) 211 Carneros, CA - Chardonnay Four Applications Bloom (6/15), Pre-Close (7/12) and Veraison (8/25) and Pre-Harvest (9/3), Evaluations 1/13; 2-3 clusters per rep *treatments applied with OS at 3oz/1 gallons - **treatments applied with.25% MSO/OS Adjuvant

19 Control Fungicides Timing-bloom, preclose, veraison Dormant LLS Leaf removal Timing-Cluster set Epicuticular wax Removal of blossom debris Decreased fertilizer Reduce succulence Cluster Architecture Prevent berry touch

20 Powdery Mildew Erysiphe necator

21 Bud Perennation

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23 Chasmothecia reside on cordons

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26 Effect of Dormant or Delayed Dormant Treatment on Viability of Ascospores Trtmt Rate/A % Germ %w/appress Micronized S 5# 2 JMS Stylet Oil 2% 1 Lime Sulfur 1 g 1 Rally+Top M 6 oz LS+JMS Oil 1+2 Citricide 2% 33 4 Untreated

27 Liquid Lime Sulfur General cleanup application for many pathogens as direct spray Powdery Mildew Chasmothecia Botrytis Sclerotia Botyrosphaeria Pycnidia Eutypa Perithecia Phomopsis Pycnidia

28 Powdery mildew epidemics Grapevine powdery mildew epidemics are driven primarily by temperatures in the canopy. When temperatures are between 7 and 86 F the pathogen can reproduce (spore to new spores) as rapidly as every five days (Delp 1954). Between 86 to 92 F, the fungus grows at a slower pace with the time required to reproduce being 15 days. At higher temperatures, a reduction in spore production, germination, and infection occurs. When temperatures reach 33 C (92 F) or greater, E. necator is greatly reduced in its ability to grow or reproduce, and actual death occurs at 32 C if the duration is for 12 hours or more. Open canopies are detrimental to growth and survival of the pathogen; due to temperature and ultraviolet radiation.

29 Powdery Mildew of Grapevines Severity of infection is dependent on: cultivar how early disease onset occurs weather conditions during season 21-3 C 5 days 3-33 C 15 days >33 C greatly reduced Timed fungicide applications are in most cases necessary to manage the disease high costs resistance of E. necator to QoI and DMI documented Integrated Pest Management monitor the presence of the pathogen in the vineyard use of forecasting epidemiological models

30 Early season pathogen detection Monitoring for disease Spore trapping Bioindication

31 Considerations Ascospore release forecast is sometimes inaccurate Visual scouting is sometimes used after spring rainfalls to detect ascospore infections in the vineyard and start RAI Spore traps Bio-indication? Psyllobora vigintimaculata Native mycophagous beetle Obligate consumer of powdery mildew Studies suggest that adults respond to olfactory stimuli during flight Photos courtesy of Dr. Sutherland Sutherland and Parrella (29) Annals of the Entomological Society of America 12,

32 Materials and Methods Visual scouting Photo courtesy of Robin Choudhury Disease incidence Disease severity Bioindicato r presence density

33 Materials and Methods: spore traps Operate continuously battery operated - solar powered trap change: Weekly from 3/1 to 6/3 5.1 L/min 162 L/min 2 steel rods (1.5x4 mm) grease covered 1 ionic stub covered with double sided tape Manufactured by Dr. W. F. Mahaffee USDA-ARS HCRL Corvallis, OR Manufactured by D&S Scientific LSU Business and Technology Center

34 Materials and Methods: spore traps DNA extraction PowerSoil DNA extraction kit (Mobio) Real-Time PCR with specific primers* and probes** *Falacy et al.(27) Phytopathology, 97 (1): ; **Mahaffee et al. (in preparation)

35 Disease severity (%) RESULTS: pathogen detection Vineyard Location variety Budbreak Date first positive rods ionic beetle visual Sacramento Co. Chardonnay 3/25 4/8 4/22 4/12 4/26 Solano Co. Thompson s. 4/1 4/26 5/3 6/2 4/19 Fresno Co. trial E Thompson s. 3/16 3/17 4/4 3/21 4/18 Fresno Co. trial M Thompson s. 3/16 4/25 5/27 5/9 5/9 Monterey Co. Chardonnay 3/16 3/28 4/21 n.d. 4/ y= x.226(x-1511) 2 R 2 =.48 n = 43 5.E+4 1.E+4 1.5E+5 2.E+5 2.5E+5 Estimated spore density/week

36 Pathogen Biology Effects of: Moisture Temperature Light RH Wind speed

37 Conidia/Leaf Area, mm2 Conidia/Leaf Area, mm2 Conidia/Leaf Area, mm2 Spore Production after Treatment at 3 C Spore Production after Treatment at 32 C /4 1/ / /4 1/ / Duration, hr Duration, hr Spore Production after Treatment at 34 C 25 2 C F /4 1/ / Duration, hr

38 Conidia/Leaf Area, mm2 Conidia/Leaf Area, mm2 Conidia/Leaf Area, mm2 Spore Production after Treatment at 36 C Spore Production after Treatment at 38 C /4 1/ / Duration, hr 1/4 1/ / Duration, hr Spore Production after Treatment at 4 C /4 1/ /2 1 3/ / Duration, hr C 36 F

39 Conidia/Leaf Area, mm2 Conidia/Leaf Area, mm2 Spore Production after Treatment at 42 C /4 1/ / Duration, hr Spore Production after Treatment at 44 C 25 C F /4 1/ / / Duration, hr

40 Colony Survival, % Colony Survival, % Colony Survival, % Colony Expansion Survival at Day 1 after Treatment at 3 C Colony Expansion Survival at Day 1 after Treatment at 32 C /4 1/ / Duration of Treatment, hr 1/4 1/ / Duration of Treatment, hr Colony Expansion Survival at Day 1 after Treatment at 34 C 1 C F /4 1/ / Duration of Treatment, hr

41 Colony Survival, % Colony Survival, % Colony Survival, % Colony Expansion Survival at Day 1 after Treatment at 36 C Colony Expansion Survival at Day 1 after Treatment at 38 C /4 1/ / /4 1/ / Duration of Treatment, hr Duration of Treatment, hr Colony Expansion Survival at Day 1 after Treatment at 4 C 1 C F /4 1/ /2 1 3/ / Duration of Treatment, hr

42 Colony Survival, % Colony Survival, % Colony Expansion Survival at Day 1 after Treatment at 42 C /4 1/ / Duration of Treatment, hr Colony Expansion Survival at Day 1 after Treatment at 44 C C 42 F /4 1/ / / Duration of Treatment, hr

43 Conidia Germinated, % Conidia Germinated, % Conidia Germinated, % Spore Germination after Treatment at 3 C Spore Germination after Treatment at 32 C /4 1/ / /4 1/ / Duration, hr Duration, hr Spore Germination after Treatment at 34 C /4 1/ / Duration, hr C F MISSING SOME DATA

44 Conidia Germinated, % Conidia Germinated, % Conidia Germinated, % Spore Germination after Treatment at 36 C Spore Germination after Treatment at 38 C /4 1/ / Duration, hr 1/4 1/ / Duration, hr Spore Germination after Treatment at 4 C /4 1/ / / C 36 F Duration, hr

45 Conidia Germinated, % Conidia Germinated, % Spore Germination after Treatment at 42 C /4 1/ / Duration, hr C F Spore Germination after Treatment at 44 C /4 1/ / Duration, hr

46 Delay in growth (days) 8 6 3º C º C 4 2 no delay 4 2 no colonies 1/4 1/ / /4 1/ / º C 8 6 4º C 4 2 no delay 4 2 no colonies 8 6 1/4 1/ / º C 8 6 1/4 1/ / º C no colonies 1/4 1/ / /4 1/ / º C º C no colonies 1/4 1/ / /4 1/ / Duration of treatment (h)

47 Effects of Consecutive Heat Exposure Control One Exposure Two Exposures DAY 43 5 Three Exposures

48 Growth Two Potential Outcomes with multiple exposure to high temp Loss of biological function Acclimation Time Time

49 Colony Diameter (mm) Sporulation Proportion Acclimation to Heat Stress 35C Colony Diameter 35C Sporulation Days After Inoculation Days Until Sporulation Similar results at 31, 33, 35, 37, and 39 C for both colony diameter and sporulation.

50 Duration at which Biological Response Extinguished, hr Figure 1. Predicted loss of biological response as a function of temperature and duration of treatment for spore germination, colony size on day 1 and spore production. The predicted duration (h) at which the biological response is zero (x-intercept) was obtained from linear regression analysis of primary data in SAS. Predicted Loss of Biological Function germination colony size spore production Temperature, C

51 3/25 4/1 4/8 4/15 4/22 4/29 5/6 5/13 5/2 5/27 6/3 6/1 6/17 6/24 RAI Disease incidence (%) RESULTS: ascospore release Rotorod Spore Traps RAI trigger vs. Original GT model Sacramento rotorod spore trap trigger 9 GT original 8 incidence Trap tested + Ascospore release?

52 Conclusions Rotorod spore traps coupled with qpcr were the most effective in detecting early season pathogen inoculum Suitability of Rotorod spore traps to improve the precision of GT ascospore release forecast There was a significant positive correlation between disease severity and: estimated spore density caught by the Rotorod spore trap P. vigintimaculata density In 1/5 vineyards, beetles were not detected on infected plants Ionic spore traps: functionality issues

53 Cultural Control Reduce RH Increase air flow Increase sunlight penetration All can be done with use of leaf removal. Botrytis control (better than 3 fungicide apps) Leaf removal at cluster set will reduce powdery mildew by over 5% in the absence of fungicides Will allow 2X increase in spray coverage

54 Grape PM Risk Assessment Index Spray Intervals Index & Disease Pressure Pathogen Status Biologicals 1 & SARs 2 Sulfur Sterol inhibitors 3 & Strobilurlins 4-3 Low Present No spray No spray No spray 3-5 Intermed. Reproduces every 15 days 1 days 1-14 days 21 days 6 or above Reproduces every 5 days Use not recomm. 7 days 1-14 days High 1 Bacillus pumilis (Sonata) and Bacillus subtilis (Serenade) 2 SAR = Systemic acquired resistance products (AuxiGro, Messenger) 3 tebuconazole (Elite), triflumizole (Procure), myclobutanil (Rally), fenarimol (Rubigan), and triadimefon (Bayleton) 4 azoxystrobin (Abound), trifloxystrobin (Flint), kresoxim-methyl (Sovran), and pyraclostrobin/boscalid (Pristine)

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56 Virtual Weather Stations Based on existing private and fed weather stations Data extrapolated Google map Find vineyard Drop balloon

57 Formation of virtual weather stations. Hourly data from1,5 California public weather stations with 3 disease risk models (powdery mildew and Botrytis bunch rot and downy mildew, insect models). (see

58 Cultural Control Reduce RH Increase air flow Increase sunlight penetration All can be done with use of leaf removal. Botrytis control (better than 3 fungicide apps) Leaf removal at cluster set will reduce powdery mildew by over 5% in the absence of fungicides Will allow 2X increase in spray coverage

59 Powdery Mildew Soft/Biological Fungicides Sulfur: Dust Micronized df (Kumulus, Microthiol Special, Thiolux) JMS Stylet Oil Purespray Green Oil Serenade (Bacillus subtillus)- Biocontrol Sonata (Bacillus pumilus)- Biocontrol Elexa (chitosan) SAR Messenger (Harpin Protein) SAR Trilogy (Neem Oil) Copper materials-champ 5wp (Nufarm) Milstop Regalia (Knotweed) Kaligreen (Potassium bicarbonate) Vigor Cal, Vigor K Prevam (boron) Valero (cinnamic aldehyde)

60 Doug Gubler Department of Plant Pathology UC Davis CANKER DISEASES EUTYPA DIEBACK BOT CANKER BLACK MEASLES (ESCA)

61 7/9/7 12/9/7 19/9/7 25/9/7 1/1/7 8/1/7 15/1/7 23/1/7 3/1/7 7/11/7 2/11/7 27/11/7 5/12/7 13/12/7 2/12/7 28/12/7 7/1/8 14/1/8 22/1/8 29/1/8 4/2/8 11/2/8 18/2/8 25/2/8 3/3/8 11/3/8 17/3/8 Epidemiology of Botryosphaeriaceae spp. in California 24/3/8 31/3/8 7/4/8 15/4/8 21/4/8 28/4/8 5/5/8 13/5/8 2/5/8 27/5/8 2/6/8 9/6/8 16/6/8 23/6/8 3/6/8 7/7/8 15/7/8 22/7/8 29/7/8 4/8/8 11/8/8 18/8/8 26/8/8 1/9/8 9/9/8 15/9/8 23/9/8 3/9/8 7/1/8 14/1/8 21/1/8 28/1/8 3/11/7 1/11/8 17/11/8 25/11/8 1/12/8 9/12/8 16/12/8 23/12/8 3/12/8 6/1/9 13/1/9 2/1/9 27/1/9 3/2/9 1/2/9 18/2/9 24/2/9 28/2/9 4/3/9 1/3/9 17/3/9 25/3/9 1/4/9 7/4/9 15/4/9 22/4/9 1/5/9 7/5/9 15/5/9 22/5/9 Vaseline slides spore trapping results in Monterey County Bot spores Precipitation (mm) Temperature (C) Bot spores values = Total spores / 2 ml of H 2 O Úrbez-Torres et al. Plant Dis. (In revision)

62 Botryosphaeria Canker Department of Plant Pathology, UC Davis Disease cycle? Picnidia, Perithecia? Native plants fruit, nut trees Foliar symptoms??

63 % of infected wounds % of infected wounds % of infected wounds % of infected wounds November Chardonnay Time Course Inoc December 1 Lasiodiplodia theobromae d 24 d 36 d 48 d 6 d 72 d 84 d T1 T2 T3 T4 T5 T6 T7 T January Lasiodiplodia theobromae d 24 d 36 d 48 d 6 d 72 d 84 d T1 T2 T3 T4 T5 T6 T7 T February March Neofusicoccum parvum Lasiodiplodia theobromae Neofusicoccum parvum Lasiodiplodia theobromae Neofusicoccum parvum d 24 d 36 d 48 d 6 d 72 d T1 T2 T3 T4 T5 T6 T d 12 d 24 d 36 d T1 T2 T3 T4 T5 T1 T2 T

64 Necrosis Lenght (mm) % of Recovery Necrosis lenght (mm) % of Recovery Lasiodiplodia theobromae a b Wounds made each month Chardonnay Neofusicoccum 27-8 parvum Oct Nov Dec Jan Feb March Lasiodiplodia theobromae a b a b Oct Nov Dec Jan Feb March c d e Lasiodiplodia theobromae Cabernet Sauvignon Neofusicoccum parvum c c d Fungal species were not re-isolated 1 inch below end of necrosis Neofusicoccum parvum a a a a a Oct Nov Dec Jan Feb March Lasiodiplodia theobromae Neofusicoccum parvum Oct Nov Dec Jan Feb March a a a a a b a

65 Double Pruning- First pruning by tractor mounted rotary saw Final pruning late February - early March =95% disease control Canes are mechanically pruned (1-15 buds) late fall - early winter

66 Fungicide Application following final pruning Rally 6 oz + Topsin M 1.5 1bs

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68 Control of Canker Diseases Double pruning or late pruning has been shown to be effective in significantly reducing infection by: Eutypa spp., Phaeo spp., and Botryosphaeriaceae spp. Should give 95% or better control B-LOCK- dobbed or painted on wounds Vitiseal- New can be dobbed or painted on (neat)or sprayed over vine by tractor (1:1 dilution)

69 EFFICACY AND TIMING OF FUNGICIDES, BACTERICIDES, AND BIOLOGICALS for DECIDUOUS TREE FRUIT, NUT,STRAWBERRY, AND VINE CROPS 212 ALMOND PEACH/NECTARINE APPLE/PEAR PISTACHIO APRICOT PLUM CHERRY PRUNE GRAPE STRAWBERRY KIWIFRUIT WALNUT Jim Adaskaveg, Professor University of California, Riverside Doug Gubler, Extension Plant Pathologist University of California Davis Themis Michailides, Plant Pathologist University of California, Davis/Kearney Agricultural Center Brent Holtz, Farm Advisor University of California Cooperative Extension, San Joaquin County UC Davis, Dept. of Plant Pathology UC Kearney Agricultural Center Statewide I PM