Pathogen Profiles

The BSPP - Publications - Molecular Plant Pathology - Pathogen Profiles - The tomato powdery mildew fungus Oidium neolycopersici

Molecular Plant Pathology - Pathogen Profiles


The tomato powdery mildew fungus Oidium neolycopersici

Hannah Jones1, John M. Whipps2, and Sarah Jane Gurr1

1 Department of Plant Sciences, South Parks Road, University of Oxford, Oxford, OX1 3RB, UK,
2 Horticulture Research International, Wellesbourne, Warwick, CV35 9EF, UK


Summary: Powdery mildew fungus; Ascomycete although sexual stage is yet to be found; an obligate biotroph.
Identification: Superficial mycelium with hyaline hyphae; unbranched erect conidiophores; conidia, ellipsoid-ovoid or doliform, 22-46 x 10-20 Ám, lack fibrosin bodies; conidia formed singly, rarely in short chains of 2-6 conidia; appressoria lobed to multilobed, rarely nipple-shaped. Pseudoidium species.
Host range: Broad, reported to attack over 60 species in 13 plant families, particularly members of the Solanaceae and Curcubitaceae.
Disease symptoms: Powdery white lesions on all aerial plant parts except the fruit. In severe outbreaks the lesions coalesce and disease is debilitating.
Agronomic importance: Extremely common in glasshouse tomatoes world wide but increasing in importance on field grown tomato crops.
Control: Chemical control and breeding programmes for disease resistance.


Powdery white lesions of O. neolycopersici on tomato (var. Moneymaker) leaves but the fruit is uninfected.


Paired hyphal appressoria


Two conidiophores bearing a single 
apical and near mature ellipsoidal conidium

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