BACTERIAL DISEASES OF STONE FRUIT: SPOTS AND CANKERS · 2017-08-01 · BACTERIAL DISEASES OF STONE...
Transcript of BACTERIAL DISEASES OF STONE FRUIT: SPOTS AND CANKERS · 2017-08-01 · BACTERIAL DISEASES OF STONE...
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BACTERIAL DISEASES OF STONE FRUIT: SPOTS AND CANKERS
December 16, 2015Kari Peter, Ph.D.Department of Plant Pathology and Environmental MicrobiologyPenn State University Fruit Research and Extension CenterBiglerville, [email protected] 717-677-6116 Ext. 223 @drtreefruit
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Overview
– Predisposing factors
– Disease Cycle– Symptoms– Management
Bacterial cankerPseudomonas syringae pv. syringaePseudomonas syringae pv. morsprunorum
Bacterial spotXanthomonas arboricola pv. pruni(Xap)
G. Sundin, MSU
S. Bardsley, PSU
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Bacterial Spot• Predisposing factors favoring the occurrence
of bacterial spot Cultivar susceptibility
Early bud break and early fruit ripening
Sandy soils (ring nematode) Very clay soils (drainage)
~ 86 °F temperature
Relative humidity of 100% over a period of 3 days = appearance of disease
http://www.ent.uga.edu/peach/peachhbk/pdf/stages.pdf
Forestryimages.org
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Bacterial Spot Disease CycleSpring
SummerFall/Winter
Polycyclic diseaseOptimum conditions:Warm and wetDisease slows down:Hot and dry
Overwinter in cankers, infected buds, leaf scars
First infect leaves
Infect leaves and fruit
Left untreated: bacterial
populations “explode”
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Bacterial Spot Symptoms - Twigs
• Cankers• Bark cracking• Black Tip
• Lack of vegetative growth• Overwintering site for bacteria
D. Ritchie, NCSU
K. Peter, PSU
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Bacterial Spot Symptoms - Leaves
Bacterial Spot
Copper/Chemical Injury
• Round (like a water droplet)
• Follows spray pattern
• “Swiss cheese”
• Yellowing not always associated with lesions
• Defoliation of older leaves
• Captan and sulfur injury: similar symptoms
• Angular• Always
bordered by the veins
• Few or many lesions
• Yellowing associated with lesions
Defoliation– it does not take many lesions for this to occur
K. Peter, PSU
K. Peter, PSU
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See spots? Ask yourself:• Are the spots angular?• Are the spots defined
by the small leaf veins?
Bacterial Spot Symptoms - Leaves
K. Peter, PSU
Early symptoms –light green water-soaked lesions
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See spots? Ask yourself:• Are the spots angular?• Are the spots defined
by the small leaf veins?
Bacterial Spot Symptoms - Leaves
K. Peter, PSU
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Bacterial Spot Symptoms - Fruit• Early Season Lesions
– 3 weeks after petal fall– Irregularly shaped– Pits extend deep into fruit
• Late Season Lesions– Shallow pits – Skin Cracking– Secondary infection: brown rot
Early season
After pit-hardening
Bill Shane, MSU
K. Peter, PSU
S. Bardsley, PSU
S. Bardsley, PSU
Japanese plum
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Bacterial Spot Symptoms - FruitNot to be confused with Peach Scab
– Circular lesions– Dark olive-brown, fuzzy lesions
– Lesions form pattern– No fruit surface pitting– No foliar symptoms
BACTERIAL SPOT PEACH SCAB
S. Bardsley, PSU Bugwood.org
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Bacterial Spot ManagementMain Strategies
– Prune out cankers– Resistant Cultivars
• Not immune = Still need control measures
– Chemical Control• Copper• Oxytetracycline• Biological products• Product rotation
http://njaes.rutgers.edu/peach/
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Bacterial Spot ManagementCopper– Fixed vs. Bluestone– Dormant spray– Cover sprays using fixed copper
• Clean fruit vs. Leaf phytotoxicity• Defoliation: older leaves
– Avoid using copper during slow drying conditions: worsens leaf phytotoxicity
– Do not mix copper with phosphorous acid products (Rampart, ProPhyt, etc.) or foliar fertilizers
K. Peter, PSU
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Bacterial Spot Management: Copper recommendations (N. Lalancette, Rutgers)
Recommended rate based on the metallic copper concentration of 0.5% = 1XCan increase concentration to 2X (1%multiply current recommended rate times 2)
** Be sure to monitor shoot s for increase in defoliation when using 2X rate**
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Bacterial Spot Management
Oxytetracylcine (Mycoshield, FireLine)– Suppresses bacteria– 48 hr control window (UV degradation) – Risk of resistance– Persistent yield loss– Best when used in rotation with other products– Label limitations
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Bacterial Spot ManagementA plan…
– Start applications late petal fall to early shuck split– Spray 7 – 14 days according to conditions– Rotating other products with oxytetracycline (21
day PHI) and copper (PHI varies)• Serenade Optimum (14 oz/A) or Double Nickel (1 qt/A)
– Works well in rotation– Can be tank mixed with oxytet
– For apricots, plums, etc: Cueva, Badge, Kocide, etc; Serenade Optimum, Double Nickel
– ** Always double check the label**– Phosphorous acid products ineffective
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If your crop was frozen out: you still need to control for bacterial spot!
• If you don’t control the disease in no-crop years:• Build up of inoculum—issues for subsequent
years• Stress – defoliation; weakens tree making it
more susceptible to bacterial spot in coming years
Bacterial Spot Management
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Overview
– Predisposing factors
– Disease Cycle– Symptoms– Management
Bacterial cankerPseudomonas syringae pv. syringaePseudomonas syringae pv. morsprunorum
Bacterial spotXanthomonas arboricola pv. pruni(Xap)
G. Sundin, MSU
S. Bardsley, PSU
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Bacterial Canker
Perpendicular VVertical AxisMarchantVogel SlenderSpindleModified Central Leader Spanish Bush
Ranked in order of increasing vulnerability to canker infections Training systems
• Predisposing factors favoring the occurrence of bacterial canker
Least susceptible
Most susceptible
Source: http://nysipm.cornell.edu/grantspgm/projects/proj09/fruit/carroll5.pdf
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Bacterial Canker• Predisposing factors favoring the occurrence of
bacterial canker
Cultivar susceptibility – varies by cultivar• Sweet cherry, sour cherry, plums, prunes,
peaches
Rootstock susceptibility• Gisela rootstocks highly susceptible• Mazzard more resistant
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Bacterial Canker• Predisposing factors favoring the occurrence of
bacterial canker Acidic soils Sandy and clay soils Nutrient deficiency High ring nematode populations
Winter pruning Spring freezes Bacteria: Ice nucleation proteins & frost injury
• Proteins allow water to freeze at higher temperatures resulting injury to the plant
• Bacteria “feed” on the nutrients released by the injured plant tissue
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Bacterial CankerFavorable conditions - susceptibility
• Mid-April (cool, wet, frost injury):– Bacteria overwintering in buds, cankers– P. syringae populations increase 10 – to 100 – fold during
bloom (blossom infection – blossom blast)• Summer:
– Humid, wet weather: symptoms on leaves and fruit– Hot and dry conditions: P. syringae populations low
• Autumn rains and cooler temperatures:– P. syringae detected at high levels prior to and during leaf fall
• *** Infection at leaf scars can be high• Early to mid-winter
– Bacteria overwinter in cankers, dead buds, healthy buds– Exposed to severe temperatures increases chance of infection
**Wind and rainstorms move the bacteria
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Bacterial Canker Symptoms
Blossom – Blossom Blast
G. Sundin, MSU
• Not to be confused with blossom blight caused by the fungus causing brown rot
• No sporulation(differentiates from brown rot)
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Bacterial Canker SymptomsFruit
• Sporadic• Water – soaked lesions• Chocolate – brown lesions
Leaves• Sporadic• Necrotic lesions, chlorotic rings• “Shot hole” appearance• Lesions occur along leaf margin
– curling effect
www.omafra.gov.on.ca
K. Peter, PSU
W. Turechek, USDA-ARS
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Bacterial Canker SymptomsBranches and Trunk
• Facilitated by stress– Spring frost– Severe winter freezes– Water – soaking– Blossom infection– Pruning wounds– Insect injuries
• Sunken bark• Amber gummosis• Girdled branches and
trunks• Limb or tree death
• No alternating callus rings
http://commons.wikimedia.org/wiki/File:Bacterial_Canker_-_Gummosis_on_Cherry.JPG http://commons.wikimedia.org/wiki/File:Bacterial_Canker_on_Cherry.JPG
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Bacterial Canker Management• Goal: reduce number of bacteria before trees
enter susceptible period
• Using Copper*– Copper alone: evidence shows limited ability to
control– Bordeaux mixture PLUS vegetable oil
• Win Cowgill – Rutgers• Described:
http://jerseyfruitagupdates.blogspot.com/2012/09/spray-cherries-for-bacterial-canker.html
– Sept, Oct, Nov, and in spring– EXAMPLE:Timing Copper sulfate Lime Water Veg. OilSept 4 lb 6 lb 100 gal 2.8 qtOct - early 5 lb 7 lb 100 gal 2.8 qtOct – late 8 lb 10 lb 100 gal 2.8 qtNov 10 lb 10 lb 100 gal 2.8 qtSpring 5 lb 7 lb 100 gal 2.8 qt
Notes: Use Powdered copper sulfate (bluestone or blue vitriol); Use FRESH hydrated lime (good quality calcium hydroxide)
Tank ½ full of water + agitation: Add copper, then lime, then the oil
K. Peter, PSU
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Bacterial Canker Management
• Pruning* – Avoid large dormant cuts– Minimize impact of disease
with summer pruning– 12 inch rule: distances infection
from the main trunk– “Ugly stub”
www.extension.umd.edu
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Bacterial Canker Management• Avoid tree training methods that cause
injury (limb spreaders)• Remove/Prevent tree stressors
– Plant in well drained soils– Maintain adequate nutrients– Weed control: weeds support
populations of bacteria– Control nematodes– Remove wild Prunus– Do not interplant new trees with old
trees• Old trees source of bacteria
K. Peter, PSU
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Take home messages:
Bacterial spotResistant cultivarsWarm, humid temps favor high bacterial populationsDormant copper sprays; reduced rates during the seasonFavorable conditions throughout the season: Use a rotation of
products (copper, oxytetracycline, biologicals)Still need to control with or without crop
Bacterial cankerSusceptibility of rootstocks and cultivarsSpring freezes, cool fall weather promote diseaseMindful pruning – summer (low bacteria numbers)Limited control options (Bordeaux mixture in fall and early
spring)
Maintain healthy trees!
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QUESTIONS?Kari Peter, [email protected] @drtreefruit
BACTERIAL DISEASES OF STONE FRUIT: SPOTS AND CANKERS