The economic value of sustainable recycling and waste management policies: The case of a waste management crisis in South Korea.

The price of recyclable waste has declined, and China is refusing solid waste imports. As a result, recycling companies in South Korea are refusing to collect recyclable waste, which caused a solid waste management crisis in April 2018. Due to this crisis, many people are unable to discard their recyclable waste. This study aims to assess the economic value of a sustainable recycling and waste management policy to solve the waste management crisis. The analysis in this study is divided into two parts: The first part estimates the inconvenience costs to residents using a contingent valuation method, whereas the second part analyzes the preferences for a new policy using a mixed logit model with a choice experiment. The results show that mean willingness to pay (WTP) per household is 41,234 (USD 36.96) KRW/year; the total WTP would be able to increase the total disposal capacity by up to 4.51%. In addition, at an adequate price level for the policy alternative, the policy acceptance rate suggests that the price of biodegradable volume-rate disposal bags should increase by no more than KRW 66 (USD 0.06) per bag. This study provides guidance to policy makers who wish to consider both validity and acceptability.

Fumigant activity of essential oils and components of Illicium verum and Schizonepeta tenuifolia against Botrytis cinerea and Colletotrichum gloeosporioides.

To develop a natural fungicide against Botrytis cinerea and Colletotrichum gloeosporioides, a total of 25 essential oils were tested for their fumigant activity against post-harvest pathogens. The vaporous phases of oils were treated to each fungus on potato dextrose agar medium in half-plate separated Petri plates at 10 microg per plate. The essential oil of Illicium verum strongly inhibited the mycelial growth of both B. cinerea and C. gloeosporioides by over 90%. On the other hand, the essential oil of Schizonepeta tenuifolia showed inhibitory activity against mycelial growth of only B. cinerea by over 90%. Gas chromatography-mass spectrometry and bioassay indicated trans-anethole in I. verum and menthone in S. tenuifolia as a major antifungal constituent. The essential oils of I. verum and S. tenuifolia and their major constituents could be used to manage post-harvest diseases caused by B. cinerea and C. gloeosporioides.

Nematicidal and Propagation Activities of Thyme Red and White Oil Compounds toward Bursaphelenchus xylophilus (Nematoda: Parasitaphelenchidae).

The toxic and propagation effects on Bursaphelenchus xylophilus of 28 Thymus vulgaris red oil and white oil compounds were examined using direct contact and cotton ball bioassays. Results were compared with those of the trunk-injection nematicides emmamectin benzoate, levamisol hydrochloride and morantel tartrate. In direct contact bioassays, geraniol (LC(50), 0.47 mg/ml) was the most toxic compound, followed by thymol (1.08 mg/ml), carvacrol (1.23 mg/ml) and terpinen-4-ol (2.61 mg/ml). In cotton ball tests with 20 inactive compounds at 2 mg/cotton ball, p-cymene significantly inhibited propagation (propagation ratio [PR] 8), compared with the castor oil-ethanol-treated control (PR 56). Propagation stimulation was observed with (-)-caryophyllene oxide, (+)-ledene, (+)- and (-)-limonene, linalool oxide, beta-myrcene, (-)-alpha-phellandrene, (+)-alpha-pinene and gamma-terpinene (PR 63-100). The other 10 compounds exhibited low to moderate levels of propagation inhibition (PR 36-56). At 0.1 mug/cotton ball, emmamectin benzoate and morantel tartrate exhibited complete suppression of propagation, whereas a very low level of propagation inhibition was obtained from levamisol hydrochloride (PR 6). In conclusion, propagation-stimulating compounds can exist in plants in addition to nematicidal compounds, and careful use of plant preparations containing high quantities of these compounds is mandatory.