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Overview
• Boxwood Blight Symptoms and Signs
• Boxwood Blight Survey
• Uses and forms of other plants
• How can you protect your nursery
What is Boxwood Blight
• Fungus
• Cylindrocladium psuedonaviculatum
• Warm Moist Conditions
• Temps 41-86⁰F, 77⁰F Optimum
• Above 91⁰F kills mycelia
• Microsclerotia are produced.
• Survive up to 5 years in leaf debris.
Where is boxwood Blight
• Confirmed cases in
– OH, PA, NY, VA, NC, MD, OR, CT, MA, RI
– Canada (BC, ON)
• Not yet found in Indiana.
Symptoms
Plants develop small, black leaf spots
Rapid progression symptoms resulting in leaf drop and small black stem cankers.
Infected plants on residential property
www.ct.gov/caes Sharon Douglas, Connecticut Ag Experiment Station
Blighted leaves, stem lesions, and defoliation.
www.ct.gov/caes Sharon Douglas, Connecticut Ag Experiment Station
Symptoms on pachysandra in landscape
www.ct.gov/caes
Sharon Douglas, Connecticut Ag Experiment Station
Volutella Blight Looks Similar
• Causes branch dieback
• Infects winter injured plants
• Both Boxwood Blight and Volutella can occur at same time
• Get lab results!
Melodie Putnam, 2008
Boxwood Blight Survey
• 67 locations • 34 Nursery Dealers
• 33 Certified Nurseries.
• No symptoms found out of 46,000 plus plants inspected
• Too hot for disease in 2012.
Boxwood Blight Survey Cultivars Found
• Green Mtn.
• Cranberry Creek
• North Starr
• Northern Charm
• Suffruticosa
• Chicagoland Green
• Baby Gem
• Gordo
• Golden Dream
• Franklin Gem
• Green Gem
• Green Borders
• Green Velvet
• Green Tower
• Variegated English
• Korean
• Rotundifolia
• Shadow Sentry
• Vadar Valley
• Winter Beauty
• Winter Gem
• Winter Green
Boxwood Blight Survey
Boxwoods from:
13 states, 1 Canadian Province
CA, IL,IN, KY, MI, OK, TN, and WI.
Boxwoods found from:
• Connecticut, Maryland, Ohio, Oregon, Pennsylvania
• British Columbia, Canada
• This may pose a risk?
What if Boxwood Blight Gets Here?
• Sites will be managed under our clean plant laws.
• Landowners will be requested to follow best management practices to contain spread.
• Deep burial or burning.
• Protect adjacent, asymptomtic plants with fungicides.
• Fungicides are labeled for Cylindrocladium, more research is needed.
• Will we loose Boxwoods?
When Choosing Alternatives to Boxwood:
Consider Plant Form
Consider Plant Function
Consider Plant Adaptability
Inkberry Holly Ilex glabra
• Salt tolerant
• Adaptable to wet conditions
• High soil pH can lead to chlorosis
• Leaf drop can be a problem
• cv. Shamrock, Green Magic
• Southern red mite
Japanese Holly Ilex crenata
• Best look alike
• Hardiness varies among cultivars
• Chlorosis in high pH soils
• cv. Convexa (very hardy)
• Green luster in photo
Dwarf Forms of Norway Spruce Picea abies
• Many forms available
• Highly adaptable
• Probably one of the better spruces for IN
• Mites can be a problem
• Bagworm
Dwarf Alberta Spruce Picea glauca ‘Conica’
• Slow growing rounded forms, conical forms
• Tolerant of shearing
• Topiary forms available in trade
• Less tolerant of shade and shearing than boxwood
• Spruce spider mite magnets
Blue Hollies Ilex x meserveae
• Fairly adaptable to Indiana soils
• Prefer acid, but doing okay at many unlikely locations
• Tolerant of shearing
• Especially cultivar China Girl or China Boy
Little Rascal Holly Ilex x Mondo
• Very low growing tight form
• I do not have a great deal of experience with this plant
• Seen winter injury in parking lot plantings
Globe Arborvitae Thuja occidentalis
• Cultivars Tiny Tim and Hetz Midget
• Slow growing forms that require little maintenance
• Mites and bagworm
• Drought injury in 2012
Yew cultivars Taxus sp.
• Many forms available
• May already be over used?
• Very tolerant of shearing and some shade tolerance
• Root rot and edema can be issues in wet soils
Boxleaf Euonymus Euonymus japonica ‘Microphyllus’
• Plant is similar in appearance
• May not be winter hardy in northern IN
• Scale, anthracnose and crown gall can be a problem
• Prefers well drained soil
Bayberry Myrica pennsylvanica
• Coarser in texture
• Highly adaptable
• Tolerates shearing
• More pH adaptable than Inkberry holly
• Not reliably evergreen in Indiana
• May be ecotypes in trade
English Ivy Hedera helix
• Take sun or shade
• Can be sheared into many shapes
• Often gets twospotted spider mites when used in this manner
• Can be invasive
Lavendar Lanvendula cultivars
• Tolerant of shearing
• Cultivars like Hidcote and Munstead stay fairly low
• Probably more hardy than Grey Green Santolina
• Not that tolerant of wet soils
• Loved the 2012 summer
How Can I Protect My Nursery?
• Segregate boxwoods from states that have the blight
• Make sure nursery has been inspected for blight
• Hold plants for 4 weeks, inspect once a week for symptoms
• Place plants on landscape fabric so debris can be easily collected
How Can I Protect My Nursery? • Obtain a fungicide history on boxwood
imported to nursery from high risk states
• Avoid over head irrigation
• Maintain spacing for good air circulation
• Avoid pruning or working in wet plants
• Disinfect pruning shears and other tools with 70% ETOH, 10% Bleach, Lysol, Zero Tol or Green Shield.
How Can I Protect My Nursery?
• Disinfect all pots with 10% bleach before repotting boxwoods
• Do not compost dead boxwoods or bring boxwoods back to nursery cull piles
• Clean all tools and boots between job sites that have boxwoods
• Remember, there is an asymptomatic stage
What to do for suspect shipments
• Contact your DNR nursery inspector
• We will get laboratory confirmation for you
• Symptomatic plants, containers and associated soil need to be mitigated
• Asymptomatic plants will need to be treated with a fungicide and monitored
DNR Contact Information
• 1-866- NO EXOTIC
• 317-232-4120 DNR Entomology
• Ken Cote 812-332-2241