Scab Fusicladosporium carpophilum. Seasonal Scab Pressure. Items for Discussion. Petal fall, a critical stage of scab development (Dr. E.

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Effective Strategies to Combat Scab and Bacterial Spot of peach Guido Schnabel Clemson University Scab Fusicladosporium carpophilum Fruit infection economically important

for management decisions Cumulative spore production potential (18 data sets from 4 states over multiple years and cultivars) Seasonal Scab Pressure Scherm et al.

the spore production curve (max = 1) 1 8 6 4-6 -4-4 6 8 1 1 Days since shuck split % of spores produced by time of shuck split By shuck split, % of seasonal spore production

applications at that time may suppress later spore production potential Items for Discussion 1) Importance of petal fall sprays ) Validity of current Bravosulfur schedule 3)

Captan during cover sprays Petal fall, a critical stage of scab development (Dr. E.

1 Effective Strategies to Combat Scab and Bacterial Spot of peach Guido Schnabel Clemson University Scab Fusicladosporium carpophilum Fruit infection economically important Twig infection epidemiologically important (overwintering site and source of initial inoculum next spring) Time of onset, peak, and tapering-off of spore production critical for management decisions Cumulative spore production potential (18 data sets from 4 states over multiple years and cultivars) Seasonal Scab Pressure Scherm et al. (8) Relative area under the spore production curve (max = 1) Days since full bloom 9% of spores produced by 1 weeks after bloom Relative area under the spore production curve (max = 1) Days since shuck split % of spores produced by time of shuck split By shuck split, % of seasonal spore production is already achieved Highest rate of spore production is between shuck split and 1 weeks after bloom Although no fruit is present for infection before shuck split, fungicide applications at that time may suppress later spore production potential Items for Discussion 1) Importance of petal fall sprays ) Validity of current Bravosulfur schedule 3) Importance of a good fungicide at petal fall (PF) and shuck-split (SS) 4) Noteworthy results with Abound at PF and SS ) Sulfur vs. Captan during cover sprays Petal fall, a critical stage of scab development (Dr. E. Zehr) Year, treatment Stage of development or spray interval (days) (rate/acre) pf ss sf % scab 1996 Captan W (4. lb) Control Captan W (4. lb) Control 1. pf = petal fall, ss = shuck split, sf = shuck fall 1

activity during early sprays How does sulfur compare with captan in the cover sprays? Auburn University (B.

2 1 Byron, GA (Flameprince P. Brannen) 1 Peach Scab Data Byron, GA (Julyprince Dr. Phil Brannen) Potential of Abound during PF and SS sprays Resistance management (reserve strobilurins for preharvest brown rot) Antisporulant activity during early sprays How does sulfur compare with captan in the cover sprays? Auburn University (B. Boozer) Bloom/ petal fall sprays (): Bravo 7 Cover sprays (7): captan or 1-14 days Scab Incidence ( ) Fruit Marketability ( ) yr Avg Sulfur Captan yr Avg Sulfur Captan

Scab Control Petal fall sprays have value

Captan during covers depends on region and

Symptoms Mid to Late Season Canker Canker

lesions Lesions usually develop in areas of

on Young Fruit Peach scab Bacterial spot

before pit-hardening May 11 Fruit in early

3 Scab Control Petal fall sprays have value for reduction of scab Sulfur not a good choice for petal fall and shuck split applications PF, SS and sulfur/ Captan during cover sprays program very reliable Choice of sulfur vs. Captan during covers depends on region and weather PF, SS provides surprising scab control, but potential resistance concerns Bacterial Spot of Peach Xanthomonas arboricola pv. pruni Guido Schnabel, Clemson University and Dave Ritchie, NC State University Overwintering Cankers and Leaf Lesions Leaf Symptoms Mid to Late Season Canker Canker Lesions Canker Lesions Newly developed lesions Lesions usually develop in areas of leaf where moisture dries the slowest NC State University Fruit Symptoms first visible -3 weeks after shuck split Symptoms on Young Fruit Peach scab Bacterial spot Water-soaked lesions on fruit a few days before pit-hardening May 11 Fruit in early June Surface & Deep Lesions 3 May DFR Feb 9 Lesions may appear similar to injury caused by insects. Fruit are approximately 4 weeks after petal fall 3

NC State University Cultivar: Conditions for Infection -- peach cultivar susceptibility -- peach stage of growth -- weather (moisture, temperature)

% 1 9 8 7 6 4 3 1 1 3 4 6 HR R MR MS S HS 3 11 17 % 1 9 8 7 6 4 3 1 37 1 3 4 6 HR R MR MS S HS 6 Bacterial Spot Susceptibility Rating Bacterial Spot

4 NC State University Cultivar: Conditions for Infection -- peach cultivar susceptibility -- peach stage of growth -- weather (moisture, temperature) Growth Stage: Scab or BS? Rainfall (in) Bars Weather: April Apr 6 DFR Feb 9 Peach Cultivars (n=31) Developed in California Peach Cultivars (n=9) Developed in Eastern U.S. % HR R MR MS S HS % HR R MR MS S HS 6 Bacterial Spot Susceptibility Rating Bacterial Spot Susceptibility Rating DFR 6 Jan 1 DFR 6 Jan 1 Rainfall (cm) Rainfall in Relation to Peach Growth Stages Year March April May 11th 3th 31th 13th 1th Temperature (C) % Fruit of a Nectarine and Peach Cultivars Having Bacterial Spot 1998 None Surface Deep Redgold 9% 39% 31% Winblo % 34% 16% O Henry % 8% 7% 4

Cultivars Having Bacterial Spot 1999 None Surface Deep Redgold 91% 8% 1% Winblo 96% 4% % O Henry 86% 1% % 4 South Carolina Data Cover spray bactericide treatments and their associated phytotoxicity

on infected fruit, mm (7 Jul) Untreated control... 1. ±. a.88 ±. ab Mycoshield 1 ppm... 9.4 ± 3.7 bc.1 ±.11 bc Cuprofix Disperss. oz metallic Cu Cuprofix Disperss.

5 Rainfall - cm Rainfall in Relation to Peach Growth Stages Year March April May 18th 3th 7th 1th 1th Temperature - C % Fruit of a Nectarine and Peach Cultivars Having Bacterial Spot 1999 None Surface Deep Redgold 91% 8% 1% Winblo 96% 4% % O Henry 86% 1% % 4 South Carolina Data Cover spray bactericide treatments and their associated phytotoxicity and bacterial spot levels on O Henry peach in the South Carolina trial Treatment and rate/acre Cu phytotoxicity, % leaf area affected (14 Apr) Fruit disease incidence, % (1 Jul) Average lesion depth on infected fruit, mm (7 Jul) Untreated control ±. a.88 ±. ab Mycoshield 1 ppm ± 3.7 bc.1 ±.11 bc Cuprofix Disperss. oz metallic Cu Cuprofix Disperss. oz metallic Cu rotated w/ Mycoshield 1 ppm STBX-16. oz metallic Cu Biowash cleanser.6% suspension Wilt-Pruf 4% suspension.8 ±.9 b 6. ±.6 c. ±.14 bc 3.3 ±.4 b 6. ± 1.7 c.7 ±. c 31.6 ± 1.8 a.4 ± 1. c.7 ±.9 ab ± 4.4 bc.76 ±.13 ab ±. ab 1.1 ±.36 a Management Copper rate reductions are tied to crop development; rates must be dramatically reduced as the season progresses!!! First Application Delayed Dormant/Beginning of Bud-swell Late dormant application Bloom Buds Terminal Bud. lb/acre metallic copper ( lb of product) Optimal timing: 1 week before budswell Coats tree surface and reduces bacterial populations just ahead of bloom May be combined with dormant oil spray Drive slowly and use sufficient water thorough tree coverage is very important Lateral Buds

Second Application Bud-swell/Early Pink with 1/4 Inch Leaf Growth 1.

. lbs Cuprofix Ultra 4 Disperss (4% MCE)) Second spray bud swell You

rain since 1 st application Copper products are ph sensitive.

may produce phytotoxicity Third Application -% Bloom/Beginning of

1 Inch Leaf Growth. lb/acre metallic copper (1. -.

are not labeled for use after bloom and shuck split Phytotoxicity

drying conditions Fourth/Fifth Application 9-1% Petal-fall, But Before

6 Second Application Bud-swell/Early Pink with 1/4 Inch Leaf Growth 1. lb/acre metallic copper (. -. lb of product; e.g.. lbs Cuprofix Ultra 4 Disperss (4% MCE)) Second spray bud swell You can skip this spray if less than weeks have gone by with little to no rain since 1 st application Copper products are ph sensitive. Water with ph less than 6. may produce phytotoxicity Third Application -% Bloom/Beginning of Petal-fall, 1/ - 1 Inch Leaf Growth. lb/acre metallic copper (1. -. lb of product) Third application - bloom some formulations of copper are not labeled for use after bloom and shuck split Phytotoxicity watch Phytotoxicity is reduced when Cu is applied during excellent drying conditions Fourth/Fifth Application 9-1% Petal-fall, But Before Start of Shuck Split, 1 - Inch Leaf Growth. -. lb/acre metallic copper ( lb of product) Shuck-Split/Shuck-Off and Cover Sprays Oxytretracycline lb/acre (Mycoshield 17WP.7-1. lb/acre) Using a minimum of 1 gal water/acre 6

Recovery From Copper Injury to Foliage Cover sprays Alternate Mycoshield or Fireline with copper Tank mix the two if BS pressure is high Label restrictions: Cuprofix is

applications of copper: 7 Feb (budswell), 14 Mar 8% bloom, 19 Mar 3% petal-fall, and 8 Mar 9-1% petalfall.

Bacterial Spot on 3 Cultivars at Harvest -1998 Moderately Moderately Highly Treatment Resistant Susceptible Susceptible 1- Non-sprayed.

............ 4 c 6 b 76 b 4- Kocide DF 4 sprays (BS, P, B, PF), then sprays of Actigard.

-- Infections of fruit can cause significant economic loss.

7 Recovery From Copper Injury to Foliage Cover sprays Alternate Mycoshield or Fireline with copper Tank mix the two if BS pressure is high Label restrictions: Cuprofix is not labeled after SS; Nu-Cop DF may be applied through nd cover; Kocide and -3 not labeled after nd cover or within 3 wks of harvest, whichever comes first Following 4 applications of copper: 7 Feb (budswell), 14 Mar 8% bloom, 19 Mar 3% petal-fall, and 8 Mar 9-1% petalfall. April 4 April Foliar injury (yellow, shot-hole, defoliation) late May from copper applied through early May - nd cover Even the best program may not hold up % Fruit with Bacterial Spot on 3 Cultivars at Harvest Moderately Moderately Highly Treatment Resistant Susceptible Susceptible 1- Non-sprayed a a 98 a - Kocide DF 4 sprays (BS, P, B, PF) b 46 a 8 b 3- Kocide DF 4 sprays (BS, P, B, PF), then sprays of Mycoshield c 6 b 76 b 4- Kocide DF 4 sprays (BS, P, B, PF), then sprays of Actigard c b 8 b BS = bud-swell, P = pink-bud, B = bloom, PF = petal-fall Summary -- Bacterial spot occurs on twigs, leaves and fruit. -- Infections of fruit can cause significant economic loss. -- Fruit infection is most severe in years when frequent periods of rainfall occur from petal-fall through the 3 to 4 weeks following petal-fall. Acknowledgements u Phil Brannen, UGA u Dave Ritchie, NC State -- Sprays of fixed copper from late dormant bud through shuck-split/ shuck-off can reduce fruit infection. -- Time of applications is critical; sprays should be applied prior to rainfall but with sufficient time for the chemicals to dry. -- Chemical sprays, however, may fail if conditions are suitable for BS Development. 7

Oxytetracycline (OTC) Background - Member of

barrier by suppressing growth of plant-pathogenic

of applications at close intervals OTC residue (%) 1 1h

washed-off after min rainfall 1 3 4 Rain (mm) OTC

8 Oxytetracycline (OTC) Background - Member of tetracycline antibiotics - Used to control Xanthomonas arboricola pv. pruni and Erwinia amylovora - Provides protective barrier by suppressing growth of plant-pathogenic bacteria before infection - Efficacy depends on number of applications at close intervals OTC residue (%) 1 1h after spray 4h after spray min 6% of OTC washed-off after min rainfall Rain (mm) OTC residues on peach seedling leaves during simulated rain (44 mm h 1 ). Values are means and standard errors of 4 independent experimental runs. 8

Managing Stone Fruit Diseases. Mohammad Babadoost University of Illinois Tree Fruit Schools 2,3 February 2016

Managing Stone Fruit Diseases. Mohammad Babadoost University of Illinois Tree Fruit Schools 2,3 February 2016 Managing Stone Fruit Diseases Mohammad University of Illinois babadoos@illinois.edu Tree Fruit Schools 2,3 February 2016 Updates in the Spray Guides One spray guide for all fruit crops No new fungicides