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The new generation of disinfectant to treat potatoes in order to reduce the "sagte" rot caused by erwinia. Potato Wash has been extensively evaluated by the USDA, Albany researchers and by Pretoria University, Department of Plant Pathology on behalf of Potatoes South Africa.
Click the on the link below to read a particular section:
* Make Up Procedure
* Applications And Dosages
* Sanitation of Packhouses & Equipment
* Monitoring
* Dosing Equipment
* Flow Rates
* Metallurgy Of Equipment
* Dosing Calibration
Potato Wash is a broad spectrum disinfectant that can be used to inactivate bacteria and fungi associated with the decay of potatoes. The other properties of Potato Wash are :
- Inactivates bacteria and fungi independently of pH of the water.
- Non corrosive.
- Highly effective against erwinia (soft rot) and fusarium ( dry rot).
- Long lasting residual in water which continues to give protection to the potatoes in the paper bags.
- Maintains the white colour of the potato skin by stopping the blackening effect of PPO, manganese and iron.
Make Up Procedure:
- Make up in a well ventilated area.
- Pour required amount of HARVEST WASH/ POTATO WASH/ OXINE/ PUROGENE into a bucket.
- Add 1/10 the amount of ACTIVATOR PA (e.g. for 1L HARVEST WASH/ POTATO WASH/ OXINE/ PUROGENE add 100ml of ACTIVATOR PA).
- Stir or mix
- Allow 5-10 minutes for development of dark yellow brown colour. We have now produced the " activated " solution.
- Add this " activated " solution into the water you wish to treat;
OR dilute at least 1 in 10 with water (for 1L activated SOLUTION dilute down to 10 L with water) to make a working solution. This working solution is stable for 14-21 days if stored in a cool place out of direct sunlight. Subsequent dosing of this working solution must be done at 10 fold the previous dosage - i.e. If you were required to dose 1L of HARVEST WASH and you made up a working solution as illustrated above, you would need to dose 10L of the working solution.
- Please note that during the " activation " step fumes may be given off which can be irritating hence the need to undertake this step in a well ventilated area. These fumes may be seen as a white smoke particularly when the ambient temperature is high. This is means that we have exceeded the solubility of chlorine dioxide in water and the " activated 2 solution needs to be diluted either into the process water to be treated made up into a working solution.
- NOTE: There are two steps to the " activation " process:
Step 1: add HARVEST WASH / OXINE / PUROGENE to the Activator
Step 2: dilute the " activated " solution into water.
You cannot keep the " activated " solution for longer than 10 minutes.
Applications And Dosages:
Washing Of Table Potatoes.
2 litres of Potato Wash per 1000 litres of water to give a residual of 30 ppm. This is sufficient to treat approximately 25000 pockets of potatoes at a cost of 2-3 cents per pocket of potatoes.
The Department of Plant Pathology at the University of Pretoria was given the project of evaluating disinfectants which could produce more effective results than HTH or Klorman in the control of soft rot on packed table potatoes. POTATO WASH came out as the most effective product.
Storage Of Table Potatoes.
This is a major application in the USA where table potatoes can be stored for 6 - 9 months. Full approval has been obtained following the extensive research undertaken by the USDA, Albany researchers. Full information is available upon request.
Emergency Approval Granted by EPA
Application of Purogene (EPA Reg. # 9804-5 EPA Est # 9804-OK-1), has been approved by EPA for the control of Late blight on potatoes in storage. This approval has been granted under the provisions of section 18 (or crisis) exemption of the Federal Insecticide, Fungicide and Rodenticide Act, as amended, for the following states: Colorado, Idaho, Minnesota, Montana, Nebraska, Neveda, North Dakota, Oregon, South Dakota, Texas, Washington and Wisconsin.
EPA's official Section 18 website - view here
(Look under "chlorine dioxide" to see approval dates for each state)
Sanitation Of Packhouses And Equipment:
Dr Freddie Denner of the ARC, Roodeplaat has demonstrated that up to 60 % of silver scurf disease incidence could be eradicated through effective sanitation techniques in the packhouse. POTATO WASH is a product which has been extensively tested world-wide as a hard surface disinfectant.
Application:
1 litre POTATO WASH per 100 litres of water
200 ml POTATO WASH per 20 litres of water in a typical knapsack sprayer.
Monitoring:
We have the following test procedures to accurately measure the residual for effective control:
Oxystix
Titration test kit
ORP
Dosing Equipment:
For the treatment of table potatoes we have found that the most effective and cost effective means of applying POTATO WASH is via a spray over the brushes.
In this regard we have designed a simple inexpensive dosing setup that can be easily installed and offers semi-automatic dosing.
If required we can offer a comprehensive automatic dosing setup with automatic activation.
1. Installation:
Where To Install
Install our system after the last bank of the clean water sprayers above the rollers in such a way to allow a minimum of 20 -30 second interval between the last sprayer and the dryers for the potatoes.
How To Install
To install the system simply put a t-piece in the main water line, then run a line to the additional sprayers putting the injector directly in line.
Nozzle Setup
The nozzles should be set up in a 5 - 4 arrangement as indicated above to ensure a good coverage of the potatoes.
Injector Diagram
2. Technical Specifcations:
The chemical injectors are non-electric with no moving parts; they are powered by flowing liquid to inject chemicals inline.
Water Pressures And Corresponding Water Flow Rates Required By The Injector
| WATER PRESSURE bar |
OPERATING RANGE Liters / minute |
| |
MIN |
MAX |
| 0.7 |
1.90 |
13.25 |
| 1.4 |
2.08 |
16.65 |
| 2.8 |
2.65 |
20.44 |
| 4.1 |
3.03 |
24.22 |
| 6.9 |
3.79 |
30.28 |
| 13.8 |
5.30 |
41.64 |
Injector Fitting Size: BSP 3/8"
Material: Stainless Steel
3. Flow Rates:
In order for the usage of POTATO WASH to be as cost effective as possible, it is recommended to keep the flow rate of the water as low as possible. Consult the above table otherwise a flow rate of approximately 250 liters/hour is recommended.
The injector can either be fitted to the existing spray banks if the flow rate and positioning is suitable, otherwise 2 spray banks have been provided with nozzles set-up to the required flow rates.
Nozzles of the spray bank must be sized according to the flow rate required via the following formula:
No. of nozzles ´ nozzle rating (in litres/min) ´ 60 minutes = flow rate per hour.
4. Metallurgy Of Equipment:
Activated solutions of chlorine dioxide should be held in high density polyethylene tanks.
All plumbing pipes should be a minimum schedule 80 PVC (polyvinyl chloride) pipes and these need to be sealed with PTFE (polytetrafluoroethylene) tape or joint sealant.
Chemically resistant o-rings such as vinylidene fluoride (Viton) are standard.
Metals that are allowed to come into contact with chlorine dioxide are titanium, hastalloy and 316 stainless steel (ss316). Do not use mild steel, galvanised, copper / brass or aluminium when coming into contact with the activated solution of POTATO WASH.
Pumps used to deliver the activated solution need to follow the above requirements.
NOTE : No chemical or heat welding of lines or tanks is permitted it these lines or tanks hold either the activated solution or POTATO WASH.
5. Dosing Calibration:
Potato Wash Dilution
200 liter plastic tank; into this plastic tank add 25 liters POTATO WASH, to this add 2.5 liters ACTIVATOR PA and then fill the tank with water. This is your dosing solution.
Dosing Calibration
Adjust the suction adjustment screw on the injector until the correct residual is acquired. Test residual using one of the test procedures.
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