Orobanche cumana

Bedi et al. (1994) investigated the potential of Fusarium oxysporum f. sp. orthoceras isolated from diseases inflorescences of O. cumana in Bulgaria as a potential biocontrol agent. This pathogen has been studied further and has proven to be efficacious under greenhouse conditions when formulated as wheat-kaolin granules (Shabana et al., 2003, Dor et al., 2007). A combination with F. solani (a weak pathogen of O. cumana) isolated in Israel from O. aegyptiaca was found to be synergistic providing more effective control of O. cumana than either agent alone (Dor et al., 2006).;Other potential biocontrol candidates have included Aspergillus alliaceus (Aybeke et al., 2014) and Ulocladium botrytis [ Alternaria botrytis ] (MŸller-Stšver et al., 2005). In spite of this there are no reports of the current use of fungi for biological control in the field.;The one insect to have been extensively studied as a possible biocontrol agent is the dipteran Phyomyza orobanchia which feeds on a number of species of Orobanche (Kroschel and Klein, 1999). In one study in Russia, P. orobanchia was exploited on over 30,000 ha, involving the release of 5-600 adults per ha and was estimated to have reduced seed production by 82-88%. Studies on other species of Orobanche achieved over 90% reduction but only when repeated for 3-4 years. However, since seed production is not completely prevented, the benefits of this agent are dubious. In addition to this P. orobanchia itself is severely affected by the hymenopterous parasites Chalcidoidea and Braconidae (particularly Opius occulisus) and also by Cladosporium cladosporioides and various species of Fusarium (Horv‡th, 1987).;Louarn et al. (2012) have demonstrated that the arbuscular mychorrhizal fungus Rhizophagus irregularis can significantly reduce infestation of sunflower by O. cumana, by directly and indirectly reducing its germination.