Woolly apple aphid, Eriosoma lanigerum, one of the pests occurring in apple do damages on the branch and bastard slip nearby ground roots by sucking sap. Recently, seasonal population of this pest steadily increased but has scarcity the basic data relating to its ecology. This study was conducted to investigate the infested orchard ratio, environmental analysis of occurred orchard, seasonal population and parasite rate by Aphelinus mali, a natural enemy for woolly apple aphid, from 30 to 34 apple orchards, at 11 to 13 major apple producing areas in Gyeongsang-namdo and Gyeongsang-bukdo, Geolla-bukdo, and Chungchung-bukdo, during 2012 to 2013. It showed infested orchard ratio as about 35% and population density started to increase from mid-May, with its optimal density in late-June and increased again in late-September. This pest found in various rootstocks where infested orchards and could not found any significant pattern. The damage appeared in 9 to 35 year-old trees, severed rather old trees than younger trees. Also, orchards that did not eliminate bastard slip were showed high occurrence pattern. Parasite rates of Aphelinus mali showed the difference among investigated orchards but the rates showed generally increased pattern since early- July.

The phenotypic traits of 63 Asian plum varieties were investigated for three years to select those with superior qualities for breeding. Eight morphological characteristics of the flowers and fruits (e.g., stigma position, fruit skin, and flesh color) were evaluated. Phenological characteristics (e.g., blooming time and ripening time) were also monitored. Being useful traits for breeding, fruit quality factors (e.g., fruit weight, skin color, flesh color, soluble solids content, and titratable acidity) were evaluated as well. The majority of the fruits were cordate (36%) and circular (23%) in shape. Approximately 78% of the varieties showed a red skin color, whereas 67% had yellowish fruit flesh. Fruit ripening occurred from June 28th to September 5th, spanning 69 days. The average fruit weight and soluble solids content were 77.2 g and 12.2 °Brix, respectively. Regarding correlations among the characteristics, the most significant correlation coefficients were for the ripening time and fruit size parameters. Such information of Asian plum varieties will be useful for future breeding programs.

Apple is a typical climacteric fruit, whose loss of firmness during storage is associated with internal levels of ethylene. MdACS1 (1-aminocyclopropane-1-carboxylate synthase) and MdACO1 (1-aminocyclopropane-1-carboxylate oxidase) genes are characterized well as functional markers for the ethylene production of ripening apple fruit. Presence of two alleles for each gene are commonly reported in cultivated apples. MdACS1-1/1, 1-1/2 and 1-2/2 generally induce high, medium, and low ethylene production, respectively. Homozygosity of MdACO1-1 resulted in low levels of ethylene production than MdACO1-1/2 and 1-2/2. It was reported that cultivars homozygous for MdACS1-2 and MdACO1-1 had superior shelf-life with lowest ethylene production. In this study, genotypes of 42 apple cultivars including Korean-developed ones at MdACS1 and MdACO1 loci were determined. Polymorphisms were detected by PCR and were separated by electrophoresis in a 2.0% agarose gel. Of PCR products of MdACS1, the fragrament of 490 bp was corresponded to the MdACS1-1 allele and 640 bp corresponded to the MdACS1-2 allele. ACO1-1 and ACO1-2 alleles had the fragment size of 525 and 587 bp, respectively. The 42 cultivars could be grouped into three classes to each gene, MdACS1-1/1, MdACS1-1/2 and MdACS1-2/2; MdACO1-1/1, MdACO1-1/2 and MdACO1-2/2.