Presence of “Candidatus Liberibacter africanus” in the Western Cape province of South Africa

Abstract

For many years, in South Africa, Huanglongbing (HLB) was restricted to the Eastern part of the country (Rustenburg, Mpumalanga, KwaZulu-Natal) and absent from the Eastern (EC) and Western Cape (WC) provinces. In November 1994, suspicious symptoms were observed on clementine trees in the Stellenbosch area (WC). In 1996 and 1997, leaf samples from WC orchards were sent to Bordeaux for analysis and found to be infected by Candidatus Liberib- acter africanus. To confirm these results, 82 samples were collected by some of us in April 1998, and tested by PCR. The presence of Candidatus L. africanus in Stellenbosch/Paarl areas of WC was confirmed in clementine, grapefruit, and lemon. Mottled leaves of Cape chestnut ( Caloden- drum capense ), a wild rutaceous tree also gave positive PCR tests. Symptoms of Huanglongbing (HLB) were first reported in South Africa in the Rustenburg region in the late 1920s. The disease was known to be present in the citrus-growing regions of the North West Province, Mpumalanga and KwaZulu-Natal.