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Department of Horticulture, Hankyong National University, Anseong 17579, KoreaAbstract - Pink Rot on melon and White Stain Symptom on grape are caused by Trichothecium roseum, one of the most important diseases of grape and melon. These diseases have been occurred in national-wide in Korea and causes irreversible damage on the grape and the melon at harvest season. This research presents the evaluation of the capacity of Bacillus subtillis HK2 to protect both melon and grape against T. reseum and establishes its role as a biocontrol agent. In this study, we isolated a Bacillus strain HK2 from rhizosphere soil, identified it as Bacillus subtillis by 16S rRNA analysis and demonstrated its antifungal activity against T. roseum . Under I-plate assay it was observed that the effect of hyphal growth inhibition was not due to production of volatile compounds. The optimum culture condition of HK2 was found at 30 ℃ and initial pH of 7.0. Application of HK2 culture suspension reduced 90.2% of white stain symptom on grape as compared to control, resulting in greater protection to grape against T. roseum infestation. Butanol extract of HK2 culture purified using flash column chromatography. The antifungal material was a polar substance as it showed antifungal activity in polar elute. Therefore, our results indicated a clear potential of B. subtilis HK2 to be used for biocontrol of Pink rot in melon and white stain symptom on grape caused by T. roseum.

BACKGROUND: White stain symptom caused by Acremonium acutatum and Trichothecium roseum, is one of the most important diseases on the grape. This disease occurs national-wide in Korea and causes irreversible damage on grape, at harvest season. This study was conducted to develop environment-friendly control method against white stain symptom. METHODS AND RESULTS: Environment-friendly materials were tested for control activity against A. acutatum and T. roseum in vitro and in vivo. The effect of environment-friendly materials against white stain symptom on grape in farmer's greenhouse was examined. The materials, NaDCC and sulphur, were sprayed three times on the leaves and fruit of grape at the two sites of farmer's field, Anseong and Hwaseong of Gyeounggi. To evaluate control effect of NaDCC and sulphur against white stain symptom, the disease severity was investigated after the two materials were sprayed from the disease onset three times at the 7-day intervals. NaDCC showed efficacy of 59.71% for Kyoho and 72.26% for Campbell-Early, and sulphur showed 78.31% for Koyho and 66.19% for Campbell-Early. CONCLUSION: We were selected sulphur and Sodium-Dichloroisocyannurate(NaDCC) based on the results of experiments in vitro. In field test, sulphur and NaDCC showed suppressive effect in the white stain symptom of grape. These results suggested that NaDCC and sulphur selected can be used as control agents for controlling white stain symptom on grape.

BACKGROUND: The white stain symptom of grape clusters and canes by dust-like particles occurred in many vineyards recently. This study was conducted to investigate the ecological characteristics of white stain symptom in grapevines and vineyards. METHODS AND RESULTS: Optimal climate condition for white stain symptom was with 60% of humidity. Moreover, closed condition with same humidity showed higher incidence rate of white stain symptom than ventilation condition. Grape varieties with black berry skin such as Campbell-Early and Kyoho were more sensitive to white stain symptom compare to varieties with green and red berry skin. Although the pathogens were not detected until March, they increased from April, and increased sharply from mid of July. The pathogens may overwinter in the infected stems and/or on the bark as a mycelium. According to the increase of sugar content of grape from August to September, the mycelium which was parasitic on the bark grew to move to the fruits through the stems, and finally reached the fruit stalk to detach berries from the clusters. CONCLUSION: Well ventilation is recommended inside the vineyard since mid-July with roll up an insect net. In addition, infected stems and fruits should be removed out from grapevines infected with pathogens in the vineyards.

White stain symptom has been reported in the vineyards of South Korea since 1999, lowering the quality of grapes and causing serious economic losses. The fungus of white stain symptom can infect cane, internode and cluster of the grape-tree (Fig. 1). The presence of mycelia with conidiophores and conidia on the surface of the host tissue give it a white stain or powdery mildew appearance. The symptom occurred in several grape varieties, including 'Campbell-Early' and 'Kyoho'. Although the symptom was severe, it seldom resulted in appreciable damage to vine health, except the dramatic reduction of grape quality. In previous reports, the white stain symptom was caused by Acremonium sp., Trichothecium sp. [1] and Hanseniaspora sp. [2]. However, the exact identification of the causal pathogen has not yet been reported. In this study, we identified the causal pathogen associated with the white stain symptom on grapes in Gyeonggi province, Korea, based on cultural characteristics, pathogenicity, and internal transcribed spacer (ITS) sequence analysis. Fig. 1 Typical appearance of the white stain symptoms on the grape fruits (A~C), petiole (D), stem (E), axillary bud (F), and cluster (G).

국립한경대학교 원예학과The effect of pre-storage treatments was investigated to control the occurrence of fruit skin stain in 'Niitaka' pears. The incidence of fruit skin stains was significantly reduced when the fruits were stored in paper bags with a yellow inner color, compared to when they were stored in paper bags with blue and red inner colors. Additionally, the pear fruits that were harvested seven days earlier than their optimum maturity date developed less fruit skin stains in cold storage and retained their quality. Storage in polyethylene (PE) bags did not control the occurrence of fruit skin stains as effectively as did bag-free storage or storage in calcium-coated bags. The dipping of the pear fruits in a chlorine dioxide and calcium solution was highly effective in reducing the fruit skin stains compared to when they were not dipped or when they were dipped only in distilled water. In particular, a 1,500 times diluted solution of sodium dichloroisocyannurate (NaDCC) reduced the incidence of fruit skin stains and the size of the lesions. No stain was observed on the skin of the fruit with a water content lower than 67.7% (w/v) during its storage. In conclusion, packaging pear fruits in bags with an inner calcium coat and dipping them in a chlorine dioxide, calcium, or NaDCC solution can effectively reduce their skin stains during their storage.Key wordspear storage, harvest time, bag coating, calcium dipping treatment