Effect of the Microalga Chlorella fusca CHK0059 on Strawberry PGPR and Biological Control of Fusarium Wilt Disease in Non-Pesticide Hydroponic Strawberry Cultivation.

The purpose of this study was to identify strawberry wilt pathogens and evaluate the efficacy of Chlorella fusca CHK0059 for improving plant growth and suppressing Fusarium wilt. We identified 10 isolates of wilt pathogens of non-pesticide Seolhyang strawberry plant, including Fusarium oxysporum f. sp. fragariae, using morphological and molecular analysis. On the 15th day after 0.4% CHK0059 treatment, the plant height of the untreated control strawberry plants was significantly greater than that of the CHK0059-treated strawberry plants. After 85 days, both treatments showed a similar tendency regarding the height of the strawberry plants. However, the thickness of strawberry leaves treated with the CHK0059 was found to be 1 mm thicker than that of the untreated control. The flowering percentage of the CHK0059 plants was also 40.2% higher on average than that of the untreated control. The chlorophyll content of strawberry leaves treated with the CHK0059 was also, on average, 6.63% higher than that of the untreated control. After 90 days of the CHK0059 treatment, the incidence of Fusarium wilt in the CHK0059-treated plants had reduced by 9.8% on average compared to the untreated control. The population density of F. oxysporum f. sp. fragariae was also reduced by approximately 86.8% in the CHK0059-treated plants by comparison to the untreated control at 70 days after treatment. The results indicate that the microalga C. fusca CHK0059 is an efficient biological agent for improving strawberry plant growth and suppressing Fusarium wilt disease in organic strawberries.

Effect of Biostimulator Chlorella fusca on Improving Growth and Qualities of Chinese Chives and Spinach in Organic Farm.

This study was conducted to investigate the efficacy of freshwater alga, Chlorella fusca on the improvement of growth and qualities in organic spinach and Chinese chives farm. The average height of Chinese chives treated with the chlorella was 3.7 cm smaller than that of the untreated. The leaf width and fresh weight of Chinese chives treated with the chlorella was 0.5 mm wider and 30.3 g heavier than that of the untreated. The commercialization and yield of Chinese chives treated with the chlorella was 11.9% and 18.3%, respectively higher than that of the untreated. Also, the disease severity of gray mold disease of Chinese chives treated with the chlorella was reduced by more than 24.2% when compared with the untreated. The thickness and number of spinach leaves treated with chlorella was 27.9% and 41.8%, respectively higher than that of the untreated. The fresh weight and yield of the spinach treated with the chlorella was 63.6% and 31.5%, respectively higher than that of the untreated. Moreover, the mineral content of K, Ca, Mg, P, Fe, and Mn were recorded higher in the spinach treated with chlorella compared with that of untreated. The results indicated that the freshwater alga, Chlorella fusca is efficient and economical biostimulant in improving plant growth and quality of Chinese chives and spinach in organic farm.

Mobility of copper, chromium and arsenic from treated timber into grapevines.

The use of chromated copper arsenate (CCA) treated timber posts as support structures in New Zealand vineyards has raised concerns regarding the release of heavy metal(loid)s from the treated timber into the environment. A laboratory experiment was set up to evaluate if post sealing by painting reduces the release rate of CCA metal(loid)s from timber posts. Three posts were painted (Gripset 38, Multi Purpose Bitumen Rubber) on the bottom part, submerged in freshwater, and the concentrations of copper (Cu), chromium (Cr) and arsenic (As) in the water were monitored over a period of 8 months. Three additional, unpainted posts were also used. The CCA contents in the water showed a clear difference between the painted and the unpainted posts, and painting the bottom of the posts reduced the release rate by 50-75%. To monitor the possible mobility of CCA from treated posts into grapevines further, an experiment with four-year-old grapevines planted into sixteen lysimeters was set up in a greenhouse. To half the lysimeters Cu, Cr and As were added to the soil surface at rates of 16, 20, and 12.5 mg/month from 15 November 2005 to 5 May 2006. The other lysimeters acted as a control. Soil solutions were collected at 50, 150 and 300 mm depths using suction cups after seven application of the CCA solution. The results showed that all the elements moved to a depth of 50 mm. Grape fruit, leaves and rachis were analysed for CCA metal(loid)s, but did not show any differences between the CCA-treated and control lysimeters. This indicated either that these metals were not taken up by grapevines or that their translocation from roots to the upper part of the vine was negligible. Further monitoring of CCA metal(loid)s in various parts of the grapevines, including roots, needs to be undertaken.