Testing the efficacy of Agrigold for the control of Pantoea allii
Mieke Daneel
ARC-Institute for Tropical and Subtropical Crops,
Private Bag X11208, Nelspruit 1200
June 2014
BlueGold Water and Chemicals
Fairland
2195
Aim
Tests were conducted to determine the efficacy of Agrigold in controlling Pantoea allii development on petri dishes.
Material and Methods
Two hundred and fifty mℓ solutions, with different concentrations of Agrigold, were prepared in Erlenmeyer flasks using autoclaved water as shown in Table 1. The pH of the solutions was adjusted to about pH 6 using either a HCℓ or NaOH solution. One mℓ of the Pantoea bacterial suspension containing ~109 cfu per mℓ, from a P. allii culture (BD 392) isolated from onion seed and obtained from ARC-PPRI, was then added to each flask. Serial dilutions were made from each flask after 30 min, 1 hour and 3 hours and plated on nutrient agar medium. Bacterial colony counts were made after an incubation period of one day. Each dilution was plated three times. The test was repeated three times over time under similar conditions.
Table 1 Treatment numbers, active ingredients and dosages tested.
| Treatment | Solution description | Dosage (mℓ /250 mℓ) |
| 1 | Water | – |
| 2 | 100 ppm Agrigold | 0.025 mℓ |
| 3 | 200 ppm Agrigold | 0.05 mℓ |
| 4 | 400 ppm Agrigold | 0.1 mℓ |
Results
The test was repeated 3 times and results can be seen in Tables 2-4. It can be seen that even at 30 minutes, viability of bacterial colonies was reduced with more than 99% compared to the untreated control. After 1 hour practically no bacterial colonies were observed in the Agrigold treatments (100, 200 and 400 ppm). Similar results were seen after 3 hours.
Table 2 Percentage reduction in viability of Pantoea allii after 30 minutes
| Treatment | Test 1 | Test 2 | Test 3 |
| 100 ppm AG | Not tested | 99.98 | 99.96 |
| 200 ppm AG | Not tested | 99.99 | 99.99 |
| 400 ppm AG | Not tested | 99.99 | 99.98 |
Table 3 Percentage reduction in viability of Pantoea allii after one hour
| Treatment | Test 1 | Test 2 | Test 3 |
| 100 ppm AG | 99.99 | 99.99 | 99.99 |
| 200 ppm AG | 99.96 | 99.99 | 99.99 |
| 400 ppm AG | 99.99 | 99.99 | 99.99 |
Table 4 Percentage reduction in viability of Pantoea allii after three hours
| Treatment | Test 1 | Test 2 | Test 3 |
| 100 ppm AG | 100.00 | 100.00 | 99.99 |
| 200 ppm AG | 99.99 | 100.00 | 99.99 |
| 400 ppm AG | 99.99 | 99.99 | 100.00 |
Conclusion
Agrigold has reduced the viability of Pantoea allii with 99% or more after a contact time of 30 minutes and more.
Agrigold can thus be described as an effective sanitizing agent killing P. allii under these conditions.