First report of ‘Candidatus Liberibacter africanus’ in Angola
In Angola, a survey on huanglongbing (associated with ‘Candidatus Liberibacter spp.’ – EPPO A1 List) was conducted in July 2019 in 2 citrus nurseries in Luanda and Caxito, and in different orchards in 7 farms surrounding Calulo and Quibala. Yellow sticky traps for insects were placed at the various localities and collected after approximately 3 weeks. Leaf galls suggesting the presence of Trioza erytreae (Hemiptera: Triozidae – EPPO A2 List – vector of huanglongbing) were observed on citrus in some locations, but no specimens were caught on traps. Citrus trees were inspected for symptoms of huanglongbing and signs of its vectors. Leaves and shoots showing suspect symptoms were sampled and tested in the laboratory (43 samples). Molecular tests (real-time PCR, sequencing) confirmed the presence of ‘Ca. Liberibacter africanus’ in 6 samples which had been collected from symptomatic citrus trees in a commercial farm near Calulo (2 Citrus reticulata and 3 C. sinensis trees) and in a nursery in Luanda (1 C. aurantifolia tree). This is the first time that ‘Ca. L. africanum’ is reported from Angola. It is concluded that further surveys are needed to determine the occurrence of huanglongbing and its vectors in Angola, and that measures should be taken to prevent further spread of the disease.
The situation of ‘Candidatus Liberibacter africanus’ in Angola can be described as follows: Present, only in some areas (first found in 2019, near Calulo and Luanda).
Sources
Fourie P, Kirkman W, Cook G, Steyn C, de Bruyn R, Bester R, Roberts R, DM Bassimba D, José CM, Maree HJ (2020) First report of ‘Candidatus Liberibacter africanus’ associated with African greening of citrus in Angola. Plant Disease (in press). https://doi.org/10.1094/PDIS-06-20-1392-PDN