Diseases and Pests of Citrus (Citrus spp.)

摘要

Citrus spp. are susceptible to a number of destructive diseases that are continuously emerging and which can severely limit production or totally decimate an industry of a country. There is the well known tristeza caused by the Citrus tristeza virus,the crippling bacterial citrus huanglongbing (Candidatus Liberibacter) and canker (Xanthomonas axonopodis pv. citri). Among fungal diseases, soil-borne infections caused by Phytophthora and postharvest pathogens are widespread and lead to heavy yield losses. Several species of phytonematodes have been detected in citrus rhizosphere, but the economic importance is known for only a few species. Tylenchulus semipenetrans occurs worldwide and can reduce yields when populations are dense. Other nematodes oflocal or regional importance include Radopholus citrophilus, Belonolaimus longicaudatus and species of Pratylenchus and Meloidogyne. Numerous species of insects have attained pest status at various locations at different times because of the damage theycause on citrus trees and fruits and the pathogens they transmit. Lepidopterans of major importance are Papilio spp., particularly the lime swallowtail butterfly, Papilio demoleus, which has recently invaded the western hemisphere. Larvae of coleopterans, Exophthalmus and Pachnaeus spp. cause extensive root damage, while adults damage young leaves. Of the aphid and psyllid species, Toxoptera citricida and Diaphorina citri, are considered as potentially the most dangerous at this time because they serveas vectors for Citrus tristeza virus and huanglongbing. This paper presents an overview of the important pathogens and pests limiting citrus production, diseases they elicit, genetic structure and diversity, and factors contributing to their emergence.