바이오 황(Bio-Sulfur)을 이용한 감귤 주요 병해충 방제 및 골분액비 제조

Abstract

1. The aim of the present study was to investigate the suppressive effects of the bio-sulfur used by eco-friendly farms on the outbreak of Elsinoe fawcettii and Diaporthe citri. To evaluate the inhibiting effect of bio-sulfur on citrus scab hyphal growth, the citrus scab pathogen Elsinoe fawcettii was cultured in PDB and agar media, and hyphal growth was observed after bio-sulfur treatment. At both for 40 and 88 h after inoculation, hyphal formation was inhibited by 0.2%, 0.1%, and 0.05% diluted bio-sulfur, and at dilutions above 0.025%, hyphal formation was observed, although growth was still inhibited, when compared to untreated cultures. Meanwhile, the occurrence of Elsinoe fawcettii on spring-flush leaves in the field was at 40.3% in control and 5.3, 10.3, 12.3, 15.3, and 24.0% when treated with Imibenconazole, 2-4 and 6-6 Lime-Bordeaux mixtures, which are also used by eco-friendly farms, 0.2% diluted bio-sulfur, lime sulfur, and 0.1% diluted bio-sulfur, respectively. The occurrence of Elsinoe fawcettii on citrus fruit was at 79.3% in control and 4.0, 33.8, 42.0, 43.3, 44.8, and 78.0% when treated with Imibenconazole, 2-4 Lime-Bordeaux mixture, 6-6 Lime-Bordeaux mixture, 0.2% diluted bio-sulfur, lime sulfur, and 0.1% diluted bio-sulfur, respectively. Because Elsinoe fawcettii can infect citrus leaves as early as May, as the spring flush begins, preventative control should be implemented by mid- to late-April, thereby increase disease control and labor saving and farming cost reducing. In an open field experiment with a plot-scale application of the chemicals: Mancozeb, lime sulfur, lime sulfur + machine oil, and bio-sulfur, the control plot showed 70.6% disease severity compared with 10.3% for the Mancozeb-treated plot. Among the eco-friendly treatments, disease severity was the lowest for the group treated with lime sulfur + machine oil (32.2%) and was at 53.9%, 58.8%, and 58.1% following treatment with lime sulfur, and bio-sulfur diluted 0.2% and 0.1%, respectively. The proportion of diseased fruit showed similar results, suggesting that bio-sulfur is an effective alternative to lime sulfur.

2. The effects of bio-sulfur, on the citrus the pest, Panonychus citri, were investigated. Three days after treatment acaricidal effects on P. citri showed at 197.6% control survival rate whereas the machine oil, and bio-sulfur diluted 0.2% and 0.1% treatments showed rates of 2.9%, 5.8%, and 9.0%, respectively. After three days, the control value for bio-sulfur diluted 0.2% was 73.2% compared with the values for the machine oil (96.4%) and bio-sulfur diluted 0.2% (94.6%) treatments. Therefore, I suggest that additional research is needed on the combined application of bio-sulfur and oils to enhance the additive control effect on citrus melanose and Panonychus citri.

3. Bacterial solubilization of phosphorus (P) from the bone meal with sulfur-oxidizing bacteria (Acidithiobacillus thiooxidans) was carried out in shake-flasks leaching experiments. The leach suspension's pH dropped from pH 5.22 to pH 1.92 during 30–40 days of leaching time and resulted in an increase in water-soluble P concentration of 23.8 g P2O5 L−1. When bio-sulfur (5% added) acts as an energy substrate for acidophilic bacteria to leach P from bone meal during the formulation of biofertilizers, it appears as an attractive approach to improve the soil fertility in organic farming.

4. Regarding the effect of bone meal liquid fertilizer on growth of ponytail radish, the group subjected to treatment with 10% concentrated NK+bone meal liquid fertilizer showed higher plant height, leaf area, root diameter, and aboveground shoot fresh weight, but not leaf number and compared to the group subjected to standard application rate. Regarding foliar fertilization, treatment did not show a significant difference in growth of the ponytail radish. However, treatment with 10% concentrated NK+bone meal liquid fertilizer resulted in a higher root length, which significantly influences the of ponytail radish. In general, a liquid fertilizer is a fast-acting fertilizer with fertilizing effects reaching 70∼100% (compared to chemical fertilizers), activates beneficial microbes in the soil, and provides the nutrients needed by plants. Therefore, it is speculated that the bone meal liquid fertilizer using Bio-Sulfur will be effective for faster cultivation of ponytail radish.