title: The tomato powdery mildew fungus Oidium neolycopersici.
abstract: summary Pathogen: Powdery mildew fungus; Ascomycete although sexual stage is yet to be found; an obligate biotroph.
  
  
  METHODS
  Superficial mycelium with hyaline hyphae; unbranched erect conidiophores; conidia, ellipsoid-ovoid or doliform, 22-46 x 10-20 microm, lack fibrosin bodies; conidia formed singly, rarely in short chains of 2-6 conidia; appressoria lobed to multilobed, rarely nipple-shaped. Pseudoidium species.
  
  
  METHODS
  Broad, reported to attack over 60 species in 13 plant families, particularly members of the Solanaceae and Curcubitaceae.
  
  
  METHODS
  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.
  
  
  METHODS
  Chemical control and breeding programmes for disease resistance.
authors.affiliation: Department of Plant Sciences, South Parks Road, University of Oxford, Oxford, OX1 3RB, UK.
authors.forename: H
authors.initials: H
authors.lastname: Jones
authors.forename: J M
authors.initials: JM
authors.lastname: Whipps
authors.forename: S J
authors.initials: SJ
authors.lastname: Gurr