Understanding and Managing Sudden Oak Death in California

SIDEBAR 1-3—Host Susceptibility Versus Spore Production

Hosts that develop severe foliar symptoms when infected by P. ramorum may not support production of significant numbers of spores. Among native species, Pacific madrone is an example that shows this pattern. In contrast, some species that are not overly susceptible to P. ramorum support production of high numbers of spores. Known relationships between host susceptibility and spore production are shown in Table 1-3.

Table 1-3—Comparison between susceptibility to Phytophthora ramorum foliar infection and P. ramorum spore production on various hosts

Amount of		Susceptibility
sporulation	High	Moderate	Low to resistant
High	Ceratonia siliqua	Castanea sativa¹	Acer pseudoplatanus
	Larix kaempferi^1,²	Cistus salvifolius	Hedera helix
	Rhamnus alaternus	Lonicera implexa	Lonicera periclymenum
	Rhododendron catawbiense¹	Michelia doltsopa¹	Quercus petraea
	Syringa vulgaris¹	Pistacia lentiscus	Quercus robur
	Umbellularia californica¹	Pistacia terebinthus	Rosa canina
		Quercus ilex¹	Rubus fructicosus
		Quercus cerris¹
		Rosa sempervirens
		Vaccinium myrtillus

Moderate	Arbutus unedo¹	Aesculus hippocastanum	Viburnum opulus¹
	Camellia japonica¹	Corylus avellana
	Fraxinus excelsior¹	Malus sylvestris
	Magnolia sp. ¹	Ulmus glabra
	Pieris japonica¹	Ulmus procera
	Quercus ilex¹
	Rhododendron catawbiense¹
	Rhododendron ponticum¹
	Viburnum tinus¹

Low	Arctostaphylos uva-ursi		Calluna vulgaris
	Kalmia latifolia		Taxus bacatta¹
	Sambucus nigra		Vaccinium x intermedium
			Vaccinium vitis-idaea
None			Empetrum nigrum
			Pinus halepensis
			Quercus pyrenaica

Source: Moralejo and others 2007

¹Found naturally infected in the United Kingdom.

²Added to list based on Webber and others 2010.

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