Alternatives to Boxwoods

Transcription

Alternatives to Boxwoods
Alternatives to Boxwoods
Ken Cote
Indiana DNR,
Division of Entomology and Plant
Pathology
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
Sharon Douglas, Connecticut Ag Experiment Station
www.ct.gov/caes
Leaf Spots
Sharon Douglas, Connecticut Ag Experiment Station
www.ct.gov/caes
Blighted leaves, stem lesions, and
defoliation.
Sharon Douglas, Connecticut Ag Experiment Station
www.ct.gov/caes
Black stem cankers and lesions
Sharon Douglas, Connecticut Ag Experiment Station
www.ct.gov/caes
Foliar symptoms: note leaf debris
Sharon Douglas, Connecticut Ag Experiment Station
www.ct.gov/caes
Infected boxwood and pachysandra
Sharon Douglas, Connecticut Ag Experiment Station
www.ct.gov/caes
Symptoms on pachysandra in landscape
Sharon Douglas, Connecticut Ag Experiment Station
www.ct.gov/caes
Volutella Blight Looks Similar
Melodie Putnam, 2008
• Causes branch
dieback
• Infects winter
injured plants
• Both Boxwood
Blight and
Volutella can occur
at same time
• Get lab results!
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
Counties Survey 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
PLANTS SIMILAR IN SHAPE
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
Green Magic Inkberry Holly
Shamrock Inkberry Holly
Leaf Retention Issues
Japanese Holly
Ilex crenata
• Best look alike
• Hardiness varies among
cultivars
• Chlorosis in high pH
soils
• cv. Convexa (very
hardy)
• Green luster in photo
Uknown Cultivar of Japanese Holly
Chlorosis in high pH sutiations
Sky pencil: good replacement of
Graham Blandy Boxwood
Ilex crenata ‘Chesapeake’
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
Picea abies ‘Pumila’
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
Other closely related forms
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
China Girl Holly
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
Mr. Bowling Ball
Thuja occidentalis ‘Bobazam’
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
Not Euonymus!
PLANTS FOR HEDGES AND
PARTERRES
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
Bayberry Hedge
Stoloniferous
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
• kcote@dnr.in.gov