Cheol Soo Yoon

Survey of Fungicide Resistance for Chemical Control of Botrytis cinerea on Paprika

Four hundred and sixty six isolates of B. cinerea were obtained from infected leaves, stems and fruits of paprika grown in greenhouses or plastic film houses in Gangwon province, Korea, between August and November in 2006 and 2007. These isolates were classified into five representative phenotypes of resistant (R) and sensitive (S) reactions as SSR, SRR, RSS, RRS and RSR according to the responses of isolates against benzimidazole, dicarboximide and N-phenylcarbamate fungicide in order. The percentage of five phenotypes were 51.3, 2.4, 35.6, 8.1 and 2.6%, respectively. The SSR phenotype (51.3%) was the most common. Among the nineteen fungicide products evaluated to compare their efficacy against gray mold pathogen on the paprika fruit inoculated with fungal mycelia, the mixture of diethofencarb and carbendazim was the most effective followed by iprodione, boscalid, the mixture of iprodione and thiophanate-methyl, fludioxonil, polyoxin-B, fluazinam, the mixture of tebuconazole and tolyfluanid and procymidone; while in the assay methods inoculated with fungal spores, the mixture of tebuconazole and tolyfluanid was the most effective in controlling gray mold followed by boscalid, fludioxonil, the mixture of diethofencarb and carbendazim and the mixture of pyrimethanil and chlorothalonil.

Influence of various nutrient concentrations on the growth and yield of summer strawberry cultivars cultivated in a hydroponic system

Summer strawberry (Fragaria x ananassa) is an important berry crop for the Korean fresh market and confectionary industry due to its pleasant taste and the health-promoting properties of its phytochemicals. ‘Albion’ and ‘Goha’ strawberry were grown hydroponically in highland altitudes (800 m above sea level) in Pyeongchang, Gangwon Province, Korea, to evaluate the effect of four nutrient concentrations [electrical conductivity (EC) 0.5, 1.0, 1.5, and 2.0 dS·m −1] on growth and yield of the varieties. Plug-grown seedlings at the 3rd leaf stage were transplanted to the hydroponic system bed containing coir dust medium on May 13, 2014. Plant growth parameters including plant height, dry weight, and root weight, as well as yield were measured during experiments. The elevation of nutrient solution EC from 0.5 to 1.0 dS·m −1 resulted in significant increase of plant height and shoot dry weight in both cultivars. As the EC was elevated in nutrient solution, the roots became longer in ‘Goha’ strawberry, but those in ‘Albion’ strawberry shortened. When the solution EC was increased to 1.0 dS·m −1, the leaf area increased significantly in ‘Goha’ but did not change significantly in ‘Albion’ strawberry. The various solution ECs did not significantly affect the yield of ‘Goha’ strawberry. However, elevation of the solution EC to 2.0 dS·m −1 significantly reduced the yield of ‘Albion’ strawberry. The treatment at 1.5 dS·m −1 led to the highest number of fruits, but the average weight of individual fruit was the lowest among treatments in ‘Goha’ strawberry. Physiological disorders were observed in the treatments of 0.5 and 2.0 dS·m −1. The above results suggested that 1.0 dS·m −1 in nutrient solution strength was the most effective for the overall production of ‘Albion’ and ‘Goha’ strawberries.

Yield and fruit quality of tomato ( Lycopersicon esculentum Mill.) cultivars established at different planting bed size and growing substrates

This study was carried out to investigate the yield and fruit quality of tomato (Lycopersicon esculentum Mill.) cultivars using different plant bed width and growing substrates in Hwacheon Farm, 2011. Transplants of tomato cultivars ‘Campari’, ‘Temptation’, ‘Annamay’, and ‘Adoration’ were planted at 20 cm, 40 cm, 60 cm, and 80 cm bed width and same cultivars were grown at cocopeat, rockwool and masato in early July, 2011 in a greenhouse. Planting bed size significantly affected the fruit number, marketable fruit number (%) and weight (g), and total yield (g) per plant. Plants grown at 60 cm bed width yielded the highest fruit number (22.4), marketable fruit number (56.0%), marketable fruit weight (356.8 g) and total yield (564.5 g) per plant. Bed width had no significant effect on fruit size and quality characters. Plants grown in cocopeat produced the highest marketable fruit number (56.2%) per plant and yielded the greatest (445.6 g) marketable yield per plant. Plants grown in cocopeat substrate produced higher fruit number (5.2%) and total yield (0.7%) than that of rockwool substrate. Fruit size and fruit quality characters showed no significant differences within growing substrates. Hence, planting the tomato cultivars in single row at 60 cm bed width is better approach to optimize the production space in greenhouse and cocopeat is recommended as potential growing substrates for tomato cultivation to increase its yield and fruit quality characters.