Issue no. 2000/03
Issue no. 2000/03
| General nursery hygiene procedures in the past have been based on information derived from scattered sources and were generally not tested on the range of pests and diseases relevant for the Australian nursery industry. A research project commissioned by NIAA and HRDC has defined the disinfection methods that will ensure clean working surfaces in the nursery. These procedures will also be used for NIASA accreditation |
Golden rules for good hygiene practices
1. Remove all dirt and organic matter (including roots and sap) from surfaces
2. Thoroughly wash the surface (benches, tools, equipment, trays, pots)
3. Treat surface with a disinfectant at the concentration and for the time recommended (Table1)
4. Keep all treated objects/surfaces in a clean area or away from dirt and other contamination until required
5. Use only freshly made disinfectant solutions when required (used disinfectant solutions may not work)
Which pests and diseases to target
Phytophthora species are the most important root pathogens of a wide range of plants in nurseries. Protocols developed for their control should therefore be the minimum standard for hygiene practices. Chalara elegans (which is also called Thielaviopsis basicola) is not as common or widespread in nurseries although it is becoming increasingly important in pansy and viola crops which are highly susceptible. As Chalara is more resistant to disinfestation, hygiene protocols that control it should be followed in nurseries where a wide range of fungal pathogens require control.
Table 1. treatments found to disinfect surfaces from plant pathogens
| Pathogen | Steel | Plastic |
| Phytophthora | 2000 ppm chlorine/1minute 2000 ppm QAT/1 minute 40000 ppm copper oxychloride/air dry* |
2000 ppm chlorine/1 minute 2000 ppm QAT/1 minute 20000 ppm copper exychloride/air dry |
| Chalara elegans | 2000 ppm choline/20 minutes 4000 ppm chlorine/1 minute QAT:only partial control at 4000ppm 20000 ppm copper oxychlorid/air dry* |
4000 ppm chlorine/20 minutes
QAT: only partial control at 4000 ppm |
| Xanthomonas campestris | 2000 ppm chlorine/1 minute 2000 ppm QAT/1 minute Copper: Only partial control at 1033 ppm |
2000 ppm chlorine/1 minute 2000 ppm QAT/1 minute Copper: Only partial control at 1033 |
*Air dry indicates a contact time of at least 5 hours
QAT test was a product called PHYTOCLEANTM which contains 100g/litre benzalkonium chloride (a quarternary amonium compound). Some QAT products may not have the same performance.
Copper tested was copper oxychloride for fungi and copper as an ethanolamine complex of copper salts (Brunnings Algae & Moss DestroyerTM) for bacteria.
Chlorine concentrations are for active ppm not product ppm as the concentration of active varies between products.
Tests were also conducted on the bacterial pathogen Xanthomonas campestris and Meloidogyne sp. nematodes. Both bacteria and nematodes can be spread on infested surfaces and cause significant losses in some crops.
Making up disinfectant solutions
Only use freshly prepared disinfectant solutions because old diluted solutions may have deteriorated or been 'used up' by previous dipping of equipment or pots and trays. Diluted chlorine solutions are particularly unstable and should be made up fresh daily, however QAT (quarternary ammonium) and copper solutions are more stable.
Undiluted chlorine should be stored in a cool room, preferable at 4°C. Use Table 2 as guide to calculating dilution rates of disinfectant to achieve the desired concentrations where specific dilutions are not indicated on labels.
Table 2. How to convert % active ingredient (a.i.) or g a.i./L to ppm (mg/L ) and how to calculate the dilution of product to the required strength
| Product strength (units) | What is the product strength in ppm? Multiply by the figure below to convert to ppm | To make up 1Lof X ppm active ingredient add Yml of product to Z ml of water | |
| Rule to find Y | Rule to find Z | ||
| % active ingredient (a.i)
Example
|
10,000 12.5 x 10,000 = |
X = Y ml product 10 x % a.i. Example: you need a 2,000 ppm solution |
Z = 1,000 - Y Z = 1,000 - 16 |
| g/L Example 125g available chlorine/L |
1,000 125 x 1,000 = |
X = Y ml product g/L a.i. Example, you need a 4,000 ppm solution 4,000 = 32 ml product 125 |
Z = 1,000 - Y Z = 1,000 - 32 |
Table 3. Control of juvenile root knot nematodes in drainage water from potting mix
| Disinfectant treatment | Exposure time (mins) |
| 2000 ppm chlorine | 40 |
| 2000 ppm QAT | 40 |
| 535 ppm copper | 80 |
Acknowledgements
The research project (NY96032) was funded by the Nursery Industry Association of Australia, the HRDC, NSW Agriculture and partners. We thank Gordon Stovold, Steven Muldoon and Suzanne Hayward, all from the Tropical Fruit Research Station, Alstonville NSW, and their Victorian colleagues for conducting this research project.
A further Nursery Paper will examine hygiene protocols for irrigation mats, sand beds, gravel and concrete. The final report on this project should be available from HRDC, (02) 9418 2200, in April 2000.