PEST MANAGEMENT PRACTICES AIMED AT CURTAILING CITRUS HUANGLONGBING DISEASE

摘要

Huanglongbing (HLB) is a devastating, insect-vectored disease of citrus sometimes referred to as citrus greening disease and putatively caused by phloem-limited bacteria within the genus 'Candidates Liberibacter.' Citrus trees infected by this disease decline in productivity; produce misshapen, inedible fruit; and eventually die, with tree mortality rates generally faster in young trees (Gottwald, 2010). Infected trees often develop shoots and branches with yellow leaves. The disease in China has been referred to as 'huanglongbing' since the late 19th century, a word which translates into English as 'yellow shoot disease'. The disease is sometimes referred to as citrus greening because fruit sometimes fail to ripen evenly, with the stylar end of the fruit remaining green. In Asia where HLB is thought to have originated, the disease is attributed to 'C. Liberibacter asiaticus' and is vectored by the Asian citrus psyllid (ACP), Diaphorina citri (Bove, 2006). Other species of 'C. Liberibacter' causing HLB in citrus occur in some countries and another psyllid (Trioza erytreae) can transmit HLB pathogens, however, the most severe cases of HLB worldwide have usually been related to 'C. Liberibacter asiaticus' and ACP. ACP (Figure 1) and Asiatic HLB (Figure 2) have spread throughout Asia, to the Saudi Arabian Peninsula, and to some Indian Ocean islands including Reunion and Mauritius (Halbert & Manjunath, 2004). ACP and Asiatic HLB now occur in South, Central and North America. Although ACP has spread to all of the citrus-growing areas in the United States (Florida, Texas, Arizona and California), HLB has been found only in Florida.