IPM Approaches for Phytophthora Root and Crown
Rot of Small Fruit Nursery Stock Dr. Johanna Del Castillo-Múnera
Dr. Cassandra Swett, Small Fruit and Grape Pathology Lab
University of Maryland, College Park
Chesapeake Green 2016
Outline
• Phytophthora root rot in Blueberries
• Phytophthora root rot in raspberries
• Phytophthora root rot in stone fruits
• Water molds
• A system approach to manage diseases
• Chemical control
• Fungicide resistance
• Conclusions
Water molds : Oomycetes
• Phytophthora is a water mold• It looks like a fungus but is not• More closely related to brown
algae than to fungi
Phytophthora cinnamomi (Leon, 2015)
They like Water!!
• Propagation: swimming and reproducing in water.
(Brooks, 2016)
Why do we care about Phytophthora ?
1. Quality issue
Plant stress after sale causes the disease to develop from undetected infection:• Drought (Retail store)• Saturated soils (standing water)
Start exhibiting disease symptoms
Asymptomatic infected plants-Look healthy, die after sale
Why do we care about Phytophthora ?
1. Quality issue, cont…
Detection of P. ramorum will result in quarantine
Asymptomatic plants can harbor quarantined pathogens--Ex: P. ramorum = regulatory issue
Why do we care about Phytophthora ?
2. Yield loss
3. Source of inoculum-spore from diseased plants get into
water
Infected plants die in the nursery
There is no cure for infected plants
Phytophthora root rot in blueberries
• Symptoms:
• Chlorosis
• Wilting and stunting
• Causal agent: Phytophthora cinnamomi
Jeffrey G. Williamson
Phytophthora root rot in blueberries
• Causal agent: Phytophthora cinnamomi
• Symptoms:
• Chlorosis
• Wilting and stunting
• Reddish-brown discoloration of
Wood at soil line
• Reduced root system
Phytophthora root rot in blueberries
• Causal agent: Phytophthora cinnamomi
• Symptoms:
• Chlorosis
• Wilting and stunting
• Reddish-brown discoloration of
Wood at soil line
• Reduced root system
• Brownish Feeder roots
• Disease occur in patches(Serdani, 2011)
Use of tolerant cultivars (Blueberries)
Tolerant Susceptible
Legacy Duke
Liberty Draper
Aurora Bluetta
Overtime Blue Ribbon
Reka Cargo
Clockwork Last Call
Bluecrop Top Shelfhttp://www.fallcreeknursery.com/commercial/variety/commercial_northern-highbush
Phytophthora root rot in Raspberries
• Symptoms: • Chlorosis of canes
• Wilting
• Number of emerging primocanes is reduced
• Leaves turn yellow, wilt, and scorch (WSU extension, 2016)
Causal agent: Phytophthora rubi, P. megasperma, P. cactorum, P. citricola, P. cryptogea.
Phytophthora root rot in Raspberries
• Causal agent: Phytophthora spp.
• Symptoms:
• Dark water-soaked lesion at the base
(PNWEP, 2011)
• Reddish brown discolorationof infected root.
(Porter, 2013)
Use of tolerant cultivars (Raspberries)
Very Resistant Moderate Resistant
Susceptible Very susceptible
Cascade Bounty
Chilliwack Amity Anne
Cascade delight
Fairview Caroline Canby
Josephine Chilcotin Chemainus
Polka Haida Heritage
Wakefield Meeker
Nootka
Rudi
Willamette
Jewel
Munger
http://sweetmansgeneralstore.com/product/heritage-red-raspberry-bareroot/
Phytophthora on stone fruits : apple, cherry, plums
• Causal agent: Phytophthora spp.
• Symptoms:
• Slow or poor growth
• Wilting, purple coloration in the foliage
(Thomson, 2000)
Phytophthora on stone fruits : apple, cherry, plums • Causal agent: Phytophthora spp.
• Symptoms:
• Slow or poor growth
• Wilting, purple coloration in the foliage
• Brownish discoloration of the crown and roots
• Decline and collapse
(Pscheidt et al. 2016)
Use of tolerant cultivars stone fruits
https://www.flickr.com/photos/jmcextman/5373033011
Apple Plums Cherry
M.9 Relatively resistant
Mazzard
M.2 Morello
M.4 Colt
http://blog.banggood.com/how-to-grow-cherry-tree-form-seed-26377.htmlhttp://www.dreamstime.com/photos-images/plums-tree-detail.html
How to submit samples?
• Fresh plant material (not entirely dead plants!)
• Wrap samples in paper towels Do NOT add moisture
• Mail samples in a sturdy container: Boxes, not bags
• Include pictures of the disease stages
• When possible send the entire plant
(Photo credit:NDSU Plant diagnostic lab)
What conditions favor the disease?
• Poorly drained or wet soils favor the pathogen.
http://www.boldsky.com/home-n-garden/gardening/2015/gardening-tips-for-wet-soil-066015.html
• Use of infested water for irrigation
• Ground to pot contact.
What conditions favor the disease?
https://aijoubonsai.wordpress.com/category/bonsai-progressions/
http://www.planetnatural.com/potting-mix-recipes/
• Ground to media contact.
• Contaminated pots from previous years.
What conditions favor the disease?
• Infected new plant material.
http://stevespeonygarden.blogspot.com/2011/04/over-view-of-blueberries.html
How does the disease develop?
Produced under high soil moisture.Temp: 68-900F
Overwinter structures: Survive many years in the soil
(DPIPWE, 2015)
How does the disease develop?
Produced under high soil moisture.Temp: 68-900F
Overwinter structures: Survive many years in the soil
(DPIPWE, 2015)
Winter
A system approach for disease management
• Integrates different risk management measures.
• How different components of a whole can influence each other.
• Overlapping and cumulative preventive measures.
Wellness program Vs. Emergency room
In Nurseries:• Prevent the need to respond with a spray
program• Crop destruction• Quarantine
http://www1.umn.edu/ohr/prod/groups/
http://www.shutterstock.com/pic-185350787/stock-vector-sick-cartoon-man-visiting-the-doctor.html
HACCP: Hazard Analysis of Critical Control Points • Risk management program:
• Identify the hazards
• Evaluate and correct the critical points of contamination.
• Widely used in the food system.
• Key points: Identify critical control points (CCP) and Hazards.
Hazards:1. New plants2. Contaminated ground3. Contaminated irrigation
water 4. Used containers5. Contaminated potted media
How can we control these hazards?
(Parke & Grünwald, 2012)
1. New plant material
CCP• Arrival of new plant material
Management practice
• Scout new material incoming to the greenhouse.
• Reject loads with infected plant material.
• Place in quarantine new plant material. (60 days from arrival)
• Do not mix new plant material with existing stock, until you are confident thenew ones are pest-free.
• Buy plants from certified nurseries.
2. Contaminated ground CCP
• Direct contact between soil and containers.
Management practice • Raise containers, add a gravel or
rock barrier between them.
(Parke & Grünwald, 2012)
2. Contaminated ground cont. CCP
• Splash dispersal of pathogens from contaminated ground.
Management practice • Prevent standing water, avoid
overwatering, improve drainage.
(Parke, 2014) (Griesbach,2012)
2. Contaminated ground cont. CCP• Movement of contaminated soil
(tools, equipment, staff)
Management practice • Clean equipment (shovels, shoes)
and vehicles after working in contaminated areas.
http://www.jeepyurongfu.com/45849001-how-to-clean-plant-containers/https://gardeninglandscaping.wordpress.com/2008/06/04/gardening-tools/
2. Contaminated ground cont.
CCP• Contamination of soil by
infested foliage.
Management practice
• Prevent and remove leafy debris from accumulating on the soil.
http://ccber.ucsb.edu/ecosystem-management/greenhouse-and-nurseryhttp://gardenrant.com/2014/11/piling-leaves-and-stacking-functions.html
3. Contaminated irrigation water
CCP
• Use of contaminated water as irrigation source (pond, river, recycled water).
Management practice • Use water from wells or municipal sources,
disinfest irrigation water.
• Test water for Phytophthora
• Contact Phytophthora testing lab: Ristaino lab NCSU
https://ristainolab.cals.ncsu.edu/teaching/phythophthora-diagnostics/
1. Filter• Slow sand filtration
• Effective at controlling Phytophthora
• Filter maintenance : Cleaning filter’s surface to avoid clogging.
biofilm (accumulation of microorganisms and organic matter)
3. Contaminated irrigation water cont.
Water disinfecting methods
http://www.oasisfilter.com/operation.htm
http://www.shubhaminc.com/multigrade-sand-filter--1603617.html
2. Disinfest • Each nursery facility selects the best disinfestation method.
• Learn more about water treatment Methods:
http://www.watereducationalliance.org/education.asp
3. Contaminated irrigation water cont.
Water disinfecting methods
Treatment Ingredient Effect Concentration
Chlorine Calcium hypocloriteSodium hypocloriteChlorine gas
Oxidize agents changed chemical structure of organic matter and may kill pathogens.
0.5-2 ppm free chlorine
Copper ionization Cu++ Cu ions are toxic to Phytophthora and Pythium
0.5 to 1 ppm CU
Heat Kill plant pathogens 203 °F for 30 S.
3. Contaminated irrigation water cont.
CCP• Splash dispersal of pathogens
• Contamination of waterways
Management practice
(Parke & Grünwald, 2012)
• Prevent standing water: well drainage, avoid over irrigation, raising containers off the ground.
• Schedule watering in the morning.
• Collect runoff water and disinfested it.
Research project: can reduced irrigation water prevent root rot diseases?
• Can a deficit irrigation system prevent pathogen spread in water and suppress infections?
• Study the development of plant diseases, pathogen infection and plant health under a deficit irrigation water treatment.
Photo credit: SCRI- CLEAN WATER3
4. Used containers
CCP• Re use of infested containers
Management practice
• Disinfesting options:• Heat: 30 min exposure to moist
heat will kill :
Pythium and Phytophthora
Fungi and bacteria
110
120
150
160
°F
(Parke & Grünwald, 2012)
• Use of new containers, or disinfest used containers
4. Used containers cont.
Container disinfecting methods
• Aerated steam. at 140°F for 30 min. Most pathogenic microorganism will be killed.
• Hot water dip. Submerge containers in hot water (180°F for 30 min).
• Disinfectants. • Peroxide (ZeroTol, OxiDate)
• Bleach
• Quaternary ammonium (Physan 20, Green-Shield CA)
Pythium and Phytophthora
Fungi and bacteria
110
120
150
160
°F
5. Contaminated potted media
• Use of contaminated mediaCCP Management practice
(Parke & Grünwald, 2012)
• Store media in an area free of contamination: away of infested water, soil, plant.
• Use clean equipment to mix planting media.
• Use media free of Phytophthora spp., disinfest ingredients before use, use “certified media” Ask supplier.
5. Contaminated potted media cont.
• Use aerated steam: Mix ingredients, place them in a steam chamber for 30 min, at 140°F.
• Composting of used media: Compost the materials keeping high temperature (140°F) during 15-25 days.
If you mix your own potting media:
Pythium and Phytophthora
Fungi and bacteria
110
120
150
160
°F
http://ccber.ucsb.edu/ecosystem-management/greenhouse-and-nursery
Chemical control
Fungicide Active Ingredient Fungicide group
Rate (per/100 gallon)
Frequency (days)
Subdue maxx Mefenoxam 4 1-2 fl oz 30-60
Aliette Fosetyl-Al 33 2.5 lb 30
Agri-Fos Phosphorous acid
33 1-3 quarts 30
Disarm-O Fluoxastrobin 11 0.15-0.6 fl oz 14-28
Orvego Dimethomorph+ ametoctadine
4540
11-14 fl-oz 14
Development of resistance
• Systemic Fungicides (SF) have a specific target in the microorganisms. As a response microorganism can change this target region or create mechanisms to “avoid” the fungicide action.
Before SF After 1st SF application
After 2nd SF application
After 3rd SF application
Fungicide rotation is important for avoiding or delaying fungicide resistance!!
Between application
Phytophthora spp. n SensitivityMefenoxam (100
µg/mL)
P. cinnamomi 77 Sensitive 17
Intermediate 57
Insensitive 3
P. citrophthora 23 Sensitive 10
Intermediate 13
Insensitive none
P. multivora 15 Sensitive 4
Intermediate 9
Insensitive 2
P. pini 21 Sensitive none
Intermediate 21
Insensitive none
P. plurivora 107 Sensitive 10
Intermediate 84
Insensitive 13
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
1 9
17
25
33
41
49
57
65
73
81
89
97
10
5
11
3
12
1
12
9
13
7
14
5
15
3
16
1
16
9
17
7
18
5
19
3
20
1
20
9
21
7
22
5
23
3
24
1
Ave
rage
Rel
ativ
e G
row
th (
%)
Isolates
Mefenoxam (100 µg/mL)
Evidence of fungicide resistant Phytophthoraisolates from Maryland Nurseries (Beaulieu,2015)
Phytophthoraspp.
n SensitivityMefenoxam(200 ug/mL)
Fosetyl-Al(500 ug/mL)
Fluoxastrobin(200 ug/mL)
Dimethomorph(400 ug/mL)
Dimethomorph + Ametoctradin
(100 ug/mL)
P. cinnamomi 3 Sensitive 3 3Intermediate
Insensitive 3 3 3
P. multivora 2 Sensitive 2 2
Intermediate
Insensitive 2 2 2
P. plurivora 13 Sensitive 11 11
Intermediate
Insensitive 13 13 13 2 2
Evidence of fungicide resistant Phytophthoraisolates from Maryland Nurseries (Beaulieu,2015)
Conclusions
• Phytophthora root rot diseases can be controlled by implementing preventive measures in nursery facilities during the entire crop cycle.
• Water is a CCP for disease management: Wet soils favor the spread and development of the disease. An adequate management of water in nurseries is a key point to control and prevent root rot diseases.
• The use of fungicides should be combine with and integrated pest management program.
Resources
• Griesbach, J. A., Parke, J. L., Chastagner, G. C., Grunwald, N. J., and Aguirre, J. 2012. Safe procurement and production manual: A systems approach for the production of healthy nursery stock. 2nd ed. Oregon Association of Nurseries, Wilsonville, OR. http://oan.org/associations/4440/files/ pdf/SafeProduction.pdf
• Pscheidt, J.W., and Ocamb, C.M. (Senior Eds.). 2016. Pacific Northwest Plant Disease Management Handbook. Oregon State University. http://pnwhandbooks.org/plantdisease/node/2951/print
• Schilder A., 2015. Excessive rain promotes Phytophthora diseases in raspberries and strawberries.
http://msue.anr.msu.edu/news/excessive_rain_promotes_phytophthora_diseases_in_raspberries_and_strawberri
• Schilder A., 2010. How to recognize Phytophthora and Pythium root rot in blueberries.
http://msue.anr.msu.edu/news/how_to_recognize_phytophthora_and_pythium_root_rot_in_blueberries
References
• Griesbach, J. A., Parke, J. L., Chastagner, G. C., Grunwald, N. J., and Aguirre, J. 2012. Safe procurement and production manual: A systems approach for the production of healthy nursery stock. 2nd ed. Oregon Association of Nurseries, Wilsonville, OR. http://oan.org/associations/4440/files/ pdf/SafeProduction.pdf
• Parke, J. L., & Grünwald, N. J. (2012). A systems approach for management of pests and pathogens of nursery crops. Plant disease, 96(9), 1236-1244.
• Pscheidt, J.W., and Ocamb, C.M. (Senior Eds.). 2016. Pacific Northwest Plant Disease Management Handbook. Oregon State University. http://pnwhandbooks.org/plantdisease/node/2951/print
• Schilder A., 2015. Excessive rain promotes Phytophthora diseases in raspberries and strawberries.
http://msue.anr.msu.edu/news/excessive_rain_promotes_phytophthora_diseases_in_raspberries_and_strawberri
• Schilder A., 2010. How to recognize Phytophthora and Pythium root rot in blueberries.
http://msue.anr.msu.edu/news/how_to_recognize_phytophthora_and_pythium_root_rot_in_blueberries
• Serdani 2011. Blueberry root rot http://pnwhandbooks.org/plantdisease/blueberry-vaccinium-corymbosum-root-rot
• Wilcox W., 1992. Phytophthora root and crown rot http://nysipm.cornell.edu/factsheets/treefruit/diseases/phyt/phyt.asp
• DPIPWE, 2015. Phytophthora root rot. Department of primary industries, parks, water and environment.
http://dpipwe.tas.gov.au/biosecurity/plant-biosecurity/pests-and-diseases/phytophthora
• PNWEP, 2011. Raspberry root rot http://pnwhandbooks.org/plantdisease/raspberry-rubus-spp-root-rot
• WSU extension 2016. Integrated pest management for raspberries http://whatcom.wsu.edu/ipm/manual/rasp/phytophthora.html