Citrus mealybug, Planococcus citri (Risso), is a known quarantine pest that is difficult to control with phosphine (PH) or low concentrations of ethyl formate (EF), particularly at low temperatures. Methyl bromide (MB) is a fumigant used for quarantine and preshipment (QPS) that can eradicate target pests with short fumigation periods. However, MB, which is an ozone-depleting substance, is scheduled to be phased out in South Korea over the next decade. There is no ideal alternative fumigant to replace MB for QPS of perishable commodities. A laboratory study was conducted to compare the individual effects of EF and PH individually, and the effects of EF mixed with PH as an MB alternative for the control of P. citri adults, nymphs, and eggs. In comparison to treatments with EF and PH individually, EF mixed with PH resulted in high toxicity to all stages of P. citri. The eggs were more tolerant than the nymphs and adults. A mixed treatment of EF and PH achieved complete control of eggs infesting pineapples at concentrations of 25.1/1.0 (EF/PH) mg/liter at 8 °C for 4 h of exposures. This new combined EF/PH fumigation technology could offer shorter exposure times and less damage to perishable commodities at low temperatures, and could potentially be extended to controlling other quarantine pests as a replacement treatment for fruit and vegetables in which methyl bromide is currently being used.

Given the lack of a resistant genetic pool in host plants, the introduction of exotic invasive pathogens can result in epidemics that affect a specific ecosystem and economy. Plant quarantine, which is designed to protect endemic plant resources, is a highly invaluable safeguard that should keep biosecurity with increasing international trade and global transportation. A total of 34 species of plant pathogens including Phytophthora infestans were documented as introduced from other countries into Korea from 1900 to 2010. The genus Phytophthora, classified in oomycetes, includes more than 120 species that are mostly recognized worldwide as highly invasive plant pathogens. After 2000, over 50 new species of Phytophthora were identified internationally as plant pathogens occurring in crops and forest trees. In Korea, Phytophthora is also one of the most serious plant pathogens. To date, 22 species (about one-fifth of known species) of the genus have been identified and reported as plant pathogens in the country. The likelihood of new exotic Phytophthora species being introduced into Korea continues to increase, thus necessitating intensive plant quarantine inspections. As new potential threats to plant health in Korea, six Phytophthora species, namely, P. alni, P. inundata, P. kernoviae, P. pinifolia, P. quercina, and P. ramorum, are discussed in this review with focus on history, disease, biology, management, and plant quarantine issues.

The genus Charitoprepes (Warren), a probable vagrant group of the family Crambidae is newly recorded for the first time from the Korean Peninsula, which was described based on C. lubricosa (Warren) from Jeju islands. Diagnosis and illustrations of detailed diagnostic characters, including genitalia are provided.

In 2020, 744 orchards in South Korea were reported to be infected by fire blight (Erwinia amylovora (Burrill) Winslow et al.). The Animal and Plant Quarantine Agency, South Korea, immediately conducted a surveillance study involving 350 orchards to determine the source of the outbreaks, and the extent of its spread and pathway(s). A delimiting survey and sampling surveys were carried out to gather and analyse data during 2020. The attempts to trace the source of the diseased plants revealed a possible pathway. Infected apple trees could have been transported to previously pest-free regions such as Gwangju and Yangju of Gyeonggido via the purchase of infected materials, e.g. from a domestic nursery. Once established, the disease could readily spread by natural means such as insects and wind into flowers, shoots and growing tips on adjacent trees. This is the likely pathway for entry of fire blight in the new region. Contaminated pruning tools may be another pathway for long-distance dispersal of this pathogen within South Korea based on data collected through this survey.

Three fungi newly intercepted from importing plants were identified in 2004. They were Ascochyta chrysanthemi on Lactuca sativa from China, A. spinaciicola on Spinacia oleracea from Denmark, and Leptosphaerulina australis on Brassica oleracea var. capitata from China. The characters of these fungi were described and illustrated.