Determination of Tylenchulus semipenetrans Biotype in Zebediela and Champagne, Republic of South Africa.

ABSTRACT

The biotype of the citrus nematode (Tylenchulus semipenetrans) from Zebediela and Champagne Citrus Estates, Republic of South Africa, was determined using 2-year-old differential hosts, namely, grape (Vitis vinifera cv. Richter 110), carrizo citrange (Citrus sinensis × Poncirus trifoliata), rough lemon (C. jambhiri), olive (Olea europaea cv. Misson), and trifoliate orange (P. trifoliata). The study was conducted under greenhouse conditions with 10 replicates. Nematodes from Zebediela and Champagne were extracted from roots through mechanical shaking, sieving, and incubation in Baermann trays and inoculated at 10,000 and 40,000 eggs and juveniles per plant, respectively. Results demonstrated that the citrus nematode from Zebediela had reproductive factors greater than one on grape, rough lemon, trifoliate orange, and carrizo citrange, but lower than one on olive. Reproductive factors were less than one for all differential hosts with the Champagne population, with olive having the lowest value. Differential-host tests using Zebediela and Champagne nematode populations suggested that the T. semipenetrans biotype is poncirus.