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Peach Rusty Spot Management. N. Lalancette, Ph.D. Assoc. Prof. & Specialist in Tree Fruit Pathology Rutgers Agricultural Research & Extension Center Bridgeton, New Jersey. Topics Importance Causal Agent Symptoms & Identification Epidemiology Management Cultural Control
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Peach Rusty SpotManagement N. Lalancette, Ph.D. Assoc. Prof. & Specialist in Tree Fruit Pathology Rutgers Agricultural Research & Extension Center Bridgeton, New Jersey
Topics • Importance • Causal Agent • Symptoms & Identification • Epidemiology • Management • Cultural Control • Chemical Control • Biorational Control • Cultivar Resistance • Summary
Importance • First observed in Idaho ‘Elberta’ peach • orchard (Blodgett, 1941) • Occurs in peach growing regions of the United States and Europe • Fruit infection approaches 100% on highly • susceptible cultivars if left unprotected • Yield loss ranging from $11/A in 1996 to • $204/A in 1997 ( NJ IPM survey)
Causal Agent • “Apple mildew on peach” (Manji, 1972, CA) • - rusty spot like symptoms • Disease gradient in peach orchard down- wind of apple block (Ries & Royce, 1978, IL) • Molecular identification of Podosphaera • leucotricha(Jankovics et. al., 2011, Hungary) • Other agents?
Symptoms & Indentification
Symptoms • Rusty spot symptoms occur only on fruit • Symptoms 1st appear 2-3 weeks after shuck split • Spots mostly circular, sometimesinitially white • Lesions turn rust-colored, from center outward
Symptoms • Lesions expand and can coalesce • Epidermis and trichomes become necrotic (die) • Lesion surface russetted, smooth (no trichomes) • Cracking can occur during pre-harvest swell
Epidemiology Temporal Analysis • Control recommendations as recent as 1995: • Apply sprays “at shuck split and continue on an eight- to 10-day schedule” • Can result in as many as 6 to 8 sprays
Epidemiology Temporal Analysis of Rusty Spot Epidemics 1999 & 2000 • Experimental Test Site • Jerseyqueen orchard w. history of rusty spot • No fungicide sprays applied all season • Disease Assessments • Examined fruit from shuck-off to harvest • Disease incidence: proportion infected fruit
Epidemiology Peach Rusty Spot Disease Progression 2000 Jerseyqueen Orchard 19June 10May
Epidemiology Peach Rusty Spot Disease Progression 2000 Jerseyqueen Orchard
Epidemiology Peach Rusty Spot Disease Progression 2000 Jerseyqueen Orchard 10May 18Aug
Epidemiology Peach Rusty Spot Disease Progression Epidemic Phases JQ ’99 JQ ’00 Growth Static Decline
Chemical Control Fungicidal Control • Application Timing? • Effective Fungicides?
Fungicide Application Timing StudyMaterials and Methods Statistical Design RCBD with five replicates in Jerseyqueen orchard Single-tree plots surrounded non-sprayed buffers Fungicide Treatments Myclobutanil (Nova 40W @ 5 oz/A in 100 gpa) 0-8 applications starting at petal fall (PF,SS,1C-6C) Chemical Control
Chemical Control Peach Rusty Spot Disease Progress Jerseyqueen - 1999 Fungicide Timing # None 0
Chemical Control Peach Rusty Spot Disease Progress Jerseyqueen - 1999 <PF Fungicide Timing # None 0 PF 1
Chemical Control Peach Rusty Spot Disease Progress Jerseyqueen - 1999 <PF SS Fungicide Timing # None 0 PF 1 PF, SS 2
Chemical Control Peach Rusty Spot Disease Progress Jerseyqueen - 1999 <PF SS 1C Fungicide Timing # None 0 PF 1 PF, SS 2 PF-1C 3
Chemical Control Peach Rusty Spot Disease Progress Jerseyqueen - 1999 <PF SS 1C 2C Fungicide Timing # None 0 PF 1 PF, SS 2 PF-1C 3 PF-2C 4
Chemical Control Peach Rusty Spot Disease Progress Jerseyqueen - 1999 <PF SS 1C 2C 3C 4C 5C 6C Fungicide Timing # None 0 PF 1 PF, SS 2 PF-1C 3 PF-2C 4 PF-6C 5-8
Chemical Control Peach Rusty Spot Disease Progress Jerseyqueen - 2000 <PF SS 1C 2C 3C 4C 5C 6C Fungicide Timing # None 0 PF 1 PF, SS 2 PF-1C 3 PF-2C 4 PF-6C 5-8
Chemical Control Peach Rusty Spot Area Under the Disease Progress Curve <PF SS 1C 2C 3C 4C 5C 6C
Chemical Control Peach Rusty Spot Area Under the Disease Progress Curve * Waller-Duncan K-ratio T test; =0.05, Kratio=100
Chemical Control Fungicidal Control • Application Timing? • Effective Fungicides?
Chemical Control Peach Rusty Spot Disease Management Validation
Disease Incidence Chemical Control Peach Rusty Spot Disease Management Validation
Chemical Control Peach Rusty Spot Relative Fungicide Efficacy ++++ = Excellent +++ = Good ++ = Fair + = Poor --- = Ineffective
Biorational Control
Biorationals Active on Powdery Mildews Biorational Control
Integrated Conventional / Biorational Programs Biorational Control
Integrated Rally / Serenade Rusty Spot Programs Biorational Control 2002
Cultivar Resistance
Cultivar Resistance • Peach Cultivar Block at RAREC • Block composition • Advanced selections from Rutgers breeding program (J. Goffreda) • Commercially available cultivars • Planting design • Early season • Early mid-season • Late mid-season • Late season
Cultivar Resistance Cultivar Suceptibility • Final Disease Incidence Assessment • Average of 2007 & 2008
Cultivar Resistance Susceptibility Classification
Cultivar Resistance Susceptibility Classification
Cultivar Resistance Susceptibility Classification
Cultivar Resistance Susceptibility Classification
Cultivar Resistance Susceptibility Classification
Summary • Rusty Spot Management • Cultural Control • Planting - locate peach orchards away from powdery mildew susceptible apples • Pruning – open canopy for better air circulation (low RH) spray coverage • Fungicidal Control • Applications - four sprays typically required • Timing - PF, SS, 1C, 2C • Disease-favorable years (e.g., 2012) - add a 3rd cover spray
Summary Rusty Spot Management Programs *Or use Serenade MAX at 2-3 lb/A