Soil Testing and Plant Diagnostic Services

Disease resistant and tolerant plant varieties

Disease resistance or tolerance does not mean the plant is immune to a disease and will show no symptoms.  Many varieties listed as disease resistant will show reduced symptom development of a specific disease when compared to a susceptible variety.  Also, some types of disease resistance are only effective against certain strains or races of the disease causing pathogen. Consequently, a variety listed here as resistant may still acquire the disease under certain circumstances.


Relatively resistant to anthracnose

  • Green ash

Tolerant of ash yellows

  • Green ash often tolerates infection without progressive decline


Most resistant to phytophthora root rot

  • Formosa
  • Fakir
  • Corrine Murrah
  • Indica hybrids as a group

Extremes in soil moisture often affect susceptibility.

Callery pear (flowering ornamental pear)

Highly susceptible to fire blight

  • 'Aristocrat'
  • 'Autumn Blaze'
  • 'Capital'
  • 'Fauriei'
  • 'Redspire'

Moderately susceptible to fire blight

  • 'Cleveland Select'
  • 'Earlyred'
  • 'Whitehouse'

Moderately resistant to fire blight

  • 'Bradford'


Resistant to fire blight

  • Cotoneaster adpressus
  • Cotoneaster apiculatua
  • Cotoneaster dielsiana
  • Cotoneaster foveolatus
  • Cotoneaster franchetii
  • Cotoneaster integerrimus
  • Cotoneaster nitens
  • Cotoneaster zabelii


Susceptible to Mycosphaerella (Septoria) leaf spot and stem canker

  • All native North American species of poplar and aspen

Check with local nurseryman or catalogs for information about resistant clones.


Resistant to cedar-apple rust, fire blight and scab

  • Adams
  • Adirondack
  • Autumn Glory
  • Beauty
  • Centurion
  • Color Parade
  • David
  • Dolgo
  • Donald Wyman
  • Doubloons
  • Gibbs Golden Gage
  • Golden Raindrops
  • Indian Summer
  • Jewelberry
  • Molten Lava
  • Narragansett
  • Pink Princess
  • Prairiefire
  • Prof. Sprenger
  • Robinson
  • Sargentii
  • Strawberry Parfait
  • Sugar Tyme
  • White Angel
  • White Cascade

Check with nurserymen or catalogs for other varieties. Resistance may vary under different growing conditions.


Somewhat resistant to black leaf spot

  • Chinese
  • Japanese
  • Siberian elms

Resistant to black leaf spot

  • Dynasty
  • Groeneveld
  • Homestead
  • Jacan
  • Pioneer
  • Regal
  • Sapporo Autumn Gold
  • Thompson
  • Urban


Resistant to phomopsis tip blight and rusts

  • Juniperus chinensis cv. Foemina and var. sargentii
  • Juniperus communis cv. Aureospica cv. Suecica and var. saxatilis
  • Juniperus sabina
  • Juniperus squamata var. fargesii
  • Juniperus virginiana cv. Tripartita


Severely affected by powdery mildew

  • Syringa vulgaris, common lilac


Very susceptible to brown spot

  • Short needle Scots pine varieties from France and Spain

Resistant to brown spot

  • Long needle Scots pine varieties from Germany and Austria

Resistant to dothistroma needle blight

  • Scots pine

Resistant to pine wilt

  • Shortleaf
  • Jack
  • Eastern white pines


Resistant to black knot

  • President

Slightly susceptible to black knot

  • Formosa
  • Shiro
  • Santa Rosa

Moderately susceptible to black knot

  • Fellenburg
  • Methley
  • Milton
  • Bradshaw
  • Early Italian

Highly susceptible to black knot

  • Stanley
  • Damson
  • Bluefree
  • Shropshire

Not susceptible to plum pockets

  • Commercial varieties from European and Asian sources

Pyracantha (firethorn)

Resistant to fire blight

  • Pyracantha coccinea cv. 'Sensation'
  • Pyracantha koidzumii and cv. 'Santa Cruz Prostrata'
  • 'San Jose' hybrid
  • 'Shawnee' hybrid

Somewhat resistant to scab

  • Pyracantha coccinea 'Government Red'
  • 'Prostrata'
  • 'Rutgers'
  • P. koidzumii 'Bella'
  • 'Duval'
  • 'Santa Cruz Prostrata'
  • 'Flava'
  • 'Shawnee' hybrid
  • 'Firey Cascade' hybrid


Resistant cultivars to phytophthora root rot

  • Caroline
  • Professor Hugo deVries
  • Red Head

Extremes in soil moisture often affect susceptibility.


Susceptible to black spot

  • Yellow or gold flowering types generally are more susceptible than red or pink ones

Resistant to black spot

  • Rosa rugosa cultivars and hybrids
  • Rosa wichuriana cultivars

Because of the wide variety of cultivars and hybrids available, consult catalogs or your local nurseryman for more information.

Susceptible to powdery mildew

  • Species and cultivars differ widely


Relatively resistant to rhizosphaera needlecast

  • Norway spruce


Highly susceptible to anthracnose

  • Native sycamores

Resistant to anthracnose

  • London plane trees, but hybridization with susceptible sycamores can produce susceptible seedlings

Resistant clonal lines to anthracnose

  • 'Bloodgood'
  • 'Columbia'
  • 'Liberty'

Updated 6/24/09