Hema Kasinathan Thesis May 1 2012.pdf - Atrium - University of ...

The fungicide Allegro ® 500F (fluazinam, ISK Biosciences Corporation, Ohio,USA) is registered for management of clubroot on Brassica vegetables in Canada. Theproducts were discovered and developed for commercialization by the Ishihara SangyoKaisha, Ltd. (ISK), Japan in the early 1990’s and 2001, respectively. Based on their modeof action, they are in group 21 and 29, respectively (Fungicide Resistance ActionCommittee 2010).Allegro is a protective pyridinamine fungicide (Suzuki et al. 1995) with a broadspectrum of activity against organisms ranging from protists to the Basidiomycota(Suzuki et al. 1995). It inhibits spore germination by uncoupling protons in theproduction of ATP (Guo et al. 1991). To be effective, it must be present in the soil aroundthe roots of a susceptible plant (Cheah et al. 1998). A drench application of Allegroprotected the taproot of Chinese cabbage, but lateral roots outside the drenched area werenot protected (Cheah et al. 1998). In plants treated with fluazinam at 1 ppm, germinationof resting spores and subsequent root hair infection was inhibited. However, there was noeffect on the pathogen once the cortical cells were infected (Suzuki et al. 1995, Tanaka etal. 1999). This is expected, since the active ingredient is not systemic, so would not be incontact with the pathogen inside the host. On high pH soils, drench application offluazinam at the rate of 1.5 kg ha -1 a.i at the time transplanting was most effective(Donald et al. 2006).Ranman is a contact fungicide in the phenylimidazole group with anti-sporulationactivity (Mitani et al. 2003) (Gentili et al. 2002). Ranman ® 400 SC (34.5% cyazofamid)is registered for use in Canada. It provides excellent control on almost all stages ofOomycete pathogens (Ohshima et al. 2004). Cyazofamid is effective against both28