Report: Efficacy of AquaHort system against Xanthomonas
"The results of our research clearly show the potential of the AquaHort-system to eliminate phytopathogenic bacteria such as Xanthomonas hortorum pv. pelargonii under practical conditions", stated prof. dr. Walter Wohanka from SRI. "However, it requires a minimum Cu-concentration of 2 ppm and exposure times of at least 4 hrs". According to Aksel de Lasson from Aqua-Hort, this is solved because the system works so that the treated water goes out to the growing area. "The water has been loaded with the free ions in the machine, and they will continue to work for many hours amongst the plants. In fact until the next watering. In this way we have a continuous treatment."
The research performed by the State Research Institutein Geisenheim:
From a 1000 L reservoir a nutrient solution contaminated with Xanthomonas hortorum pv. pelargonii was pumped with about 1 m3/h through the Aqua-Hort®-unit. After passage through the unit the solution was dumped.
Table 1: nutrient contents of the complete fertiliser FERTY® 3 MEGA (Planta Düngemittel GmbH, Regenstauf, Germany)
800 L nutrient solution were prepared by 0.5 g/L of the complete fertiliser FERTY® 3 MEGA (ingredients see table 1). The solution ready for use had a electric conductivity of about 1 mS/cm and a pH of about 7.2. On demand of the client, for the supplemental test (see below) the pH was adjusted to 6.5 by adding sulphuric acid. Preparation took place one day in advance to achieve a adaptation to the ambient temperature of about 19 °C.
Table 2: Cu-concentrations (ppm) of the treated fertiliser solution at the various repetitions (rpt.1 – rpt. 4)
Immediately before the first treatment the nutrient solution was contaminated with a rifamycin-resistant pathogen Xanthomonas hortorum pv. pelargonii (strain B047Gshm). From a 48 h plate culture (YDC agar) a bacterial suspension (Ringer solution) was prepared (OD 51-52 %) and an aliquot added to the 800 L nutrient solution to achieve a density of about 103 to 104 cfu/ml. The nominal Cu-concentrations (displayed on the unit) were 0,5, 2,0 und 4,0 ppm Cu. Additionally, in a separate trial conducted 4 weeks later, the concentration of 1 ppm at exposure times from 60 to 1440 min was tested. Table 2 shows the realised (photometrically determined) Cu-concentrations of the various treatments.
Table 3: Means of bacterial counts (cfu/ml) of Xanthomonas hortorum pv. pelargonii in a fertiliser solution after treatment at different Cu-concentrations and exposure times
Samples were taken 1 min after adjusting the respective concentration at the display (pump continuously working). The samples were immediately transferred to the lab and there stored at room temperature. To realise the various exposure times three sub-samples each were plated onto YDC-agar plates 5, 15, 30, 60 min, (2), 4 and 24 hr after the samples were taken (spiral plate; Meintrup DWS Laborgeräte GMBH, Lähden – Holte, Germany). At start and end of each treatment beside the Cu-concentration (Kupfer-Test Aquaquant®; range 0.3 – 5.0 mg/l; Merck KGaA, Darmstadt), the electric conductivity, pH and temperature of the nutrient solution were determined.
Each treatment was repeated four times. The bacterial counts (cfu/ml) were statistically analysed by ANOVA and significant differences to the control were determined by the Dunnett-test (STATISTICA for Windows version 7.1)
For more information:
Aqua Hort
Aksel de Lasson
Tell: +45 702 26 611 |
aksel@aqua-hort.dk
www.aqua-hort.dk