Screening of different citrus rootstocks against foot rot disease (Phytophthora nicotianae var. parasitica)

Identification of tolerant genotypes of citrus against Phytophthora foot rot is an eco-friendly and long term approach to combat this problem. Eight different rootstocks, viz., Carrizo [Poncirus trifoliate Raf. × Citrus sinensis (L.) Osbeck], Cleopatra [Citrus reshni Tanaka], Rough lemon [Citrus jambhiri Lush.], Karna khatta [Citrus karna Raf.], Karun jambhir [Citrus aurantium Linn.], Pectinifera [Citrus depressa Hyata], Rangpur lime [Citrus limonia Osbeck] and Troyer [Poncirus trifoliate Raf. × Citrus sinensis (L.) Osbeck] were screened against P. nicotianae var. parasitica by inoculating the young citrus seedlings with freshly prepared spore suspension. Sterlized sorghum grains were used as substrate for raising mass culture of the fungus in the screening programme. All the rootstocks screened expressed different levels of susceptibility against the disease. Cleopatra showed highly susceptible while Pectinifera exhibited slightly tolerant reaction.