Issue 111: Keeping it Clean

March/April 2010
Author: Christine Paul

According to a leading authority on greenhouse and hydroponic horticulture, maintaining rigorous hygiene practices in the greenhouse is critical to reducing costs and losses in the management of pests and diseases.

Jeremy Badgery-Parker provides an extension service on all aspects of greenhouse and hydroponic production.

Jeremy Badgery-Parker (BScAgr MBA) is the Extension Horticulturist for greenhouse and hydroponic horticulture with Industry & Investment NSW (I&I NSW). He provides an extension service on all aspects of greenhouse and hydroponic production and is involved in a variety of research and extension projects focused on the long-term development of the protected cropping industry in NSW and Australia.

Current projects include developing a business analysis and greenhouse benchmarking program for growers, investigating alternate energy sources and improving greenhouse energy efficiency, water treatment and recycling, low-cost retrofit options for greenhouses locally and in the Philippines, as well as an ongoing focus on improving general greenhouse management and implementing better pest and disease management practices. Jeremy works out of the National Centre for Greenhouse Horticulture (NCGH), Narara, on the NSW Central Coast.

“I have been involved in a HAL project looking at improving awareness of preventative pest and disease management practices. Several workshops have been run in NSW and some in SA and one in Queensland so far and the project is coming to a close shortly,” he says.

Supported by HAL and AusVeg, the project was set up to provide greenhouse growers with the basic information and skills needed for integrated and preventative pest and disease management and to assist them in overcoming barriers to adoption when implementing the foundations of integrated pest management (IPM).

Jeremy is the author of Keep it CLEAN – Reducing costs and losses in the management of pests and diseases in the greenhouse – a comprehensive guide for growers aimed at helping them establish and maintain good hygiene strategies in the greenhouse.

“The Keep it CLEAN manual – as well as some other resources, including factsheets describing 10 essential management practices describe in detail what growers should be doing in terms of good greenhouse hygiene practices,” he says.

10 essential practices for all growers
The series of HAL fact sheets are designed to show how simple, low-cost changes around the greenhouse can significantly reduce costs and losses from pests and diseases. Outlined in the fact sheets are 10 essential practices for every farm:

1. Be able to correctly identify pests and diseases (or have them identified for you) and routinely conduct a pest and disease check to ensure early detection and correct identification of problems.

The simplified pest and disease check is easy to complete because
the greenhouse is set up in advance with marked zones.

2. Action points are determined and pest and disease check information is used for all decision-making including chemical, biological, whole-crop and hot-spot treatments.

3. The greenhouse is within a ‘clean’ zone, which is quarantined from the ‘outside’ zone of the farm.

4. Check and control points are used to control movement of people, vehicles, plants and materials into the ‘clean’ zone.

Roads and paths around the greenhouses need to be kept clean and free of plants, plant material, soil and other debris.

5. Employees and visitors do not visit another greenhouse before entering your greenhouse.

6. All seedlings are checked and found free from pests and diseases before they are planted out into a clean greenhouse.

7. A 5-10 metre-wide clean buffer area is maintained around the greenhouse.

8. The greenhouse is always cleaned and disinfected before planting new crop.

9. The greenhouse and farm surrounds are kept weed-free.

A 5-10 metre weed-free buffer area is needed around every greenhouse on the farm.

10. Crop debris is removed and stored/disposed of outside.

Prevention is cheaper than treatment
Clearly, the profitability and productivity of a greenhouse can be significantly improved by minimising the losses caused by pests and diseases.

“Preventative pest and disease management is about planning, cleaning and quarantining. No single practice on its own can completely prevent pests and diseases causing losses to your crop and to your business,” Jeremy says.

Keeping the greenhouse clean and tidy is a must for all growers and keeping the floor covered makes pest and disease management even easier.

“The key to cost-effective pest and disease management is integrating the most suitable strategies from all the available options and establishing a solid prevention program.

“Integrated pest management, or IPM, is the use of multiple tactics to contain pests and diseases to tolerable levels,” he says.

Every aspect of growing a good crop is part of an integrated pest and disease management program and preventative practices make up the majority of management tactics available to growers.

“Monitoring the crop regularly and routinely enables you to find pests and diseases early. This means you will have more management options available to you,” he says.

“Do a pest and disease check in every greenhouse at least twice a week in summer and once per week in winter. Inspect at least 12 plants per greenhouse and use sticky traps.

“Set up each greenhouse beforehand and mark check points in your greenhouse to make the job easier. Use pre-prepared charts to keep record keeping fast and easy,” Jeremy advises.

“Checking pest numbers routinely enables growers to reduce the number of spray applications. For example, one grower now averages two fewer sprays per crop, saving hundreds of dollars.”

Talking greenhouse hygiene
In the following, Jeremy Badgery-Parker further shares his extensive knowledge of greenhouse hygiene strategies with PH&G readers:

PH&G: What are some of the most common mistakes growers make in terms of greenhouse hygiene?
JBP: One of the most common mistakes growers can make with respect to greenhouse hygiene is taking a short cut. The investment of time and resources into cleaning and maintaining a greenhouse and developing good hygiene practices and farm management policies can be, and is often, completely undone with a single oversight, such as not using a footbath properly or ducking back into a greenhouse to get something without ensuring that clothes, footwear or tools are clean.

The ‘Keep it clean’ project provided foot baths to participating growers. Every person entering a greenhouse must place both feet into the footbath each and every time they enter.

PH&G: Are there any extra precautions hydroponic growers should take?
JBP: Greenhouse and hydroponic growers have an important production advantage in that the production system can be completely clean and pest and disease-free at the start of the crop, unlike field or soil-based production. This pest and disease-free status needs to be protected especially because incoming problems can potentially spread faster if they get into a clean environment.

Another advantage of many hydroponic systems is that plant root zones can be kept separate to minimise the risk of diseases spreading. Growers should, where feasible, ensure that the way their hydroponic system is set up provides effective drainage and prevents root to root contact by plants.

PH&G: When checking for pests and diseases are there any crops that require more frequent monitoring than others?
JBP: All crops need to be routinely inspected – monitored – for pests and diseases. At a minimum, a pest and disease check needs to be conducted twice per week in the warmer months and at least once per week in the cooler months. Monitoring and making a record of pest and disease levels is one of the most valuable pest and disease management practices anyone can do – it is the cornerstone of effective pest and disease management in any crop.

A very simple pest and disease check procedure as well as example charts that make record keeping extremely fast and easy are described in the Keep it Clean manual.

PH&G: Can you describe how ‘action points’ are important in any greenhouse hygiene strategy?
JBP: Action points – sometimes called threshold levels – are a method of pre-planning a pest or disease management strategy. They are set points that you use to make decisions about what, if any, management action you need to take.

By creating a decision point and an action to follow if that point is reached, growers can establish objective responses and benchmarks that not only enable effective and timely management but also greatly improve efficiency, reduce costs and provide a measure by which future actions can be further improved.

Action points go hand-in-hand with effective monitoring. A number of examples are given in the Keep it CLEAN manual to illustrate how they work. The more accurate your action point, the more cost-effective your management of pests and diseases will be.

PH&G: What are some of the most common diseases and pests hydroponic growers need to monitor?
JBP: A number of key pests and diseases commonly occurring in greenhouses in Australia are described in the Keep it CLEAN manual. Effective management of pests and diseases depends on knowing the problem. Preventative practices rely on understanding the problems, knowing the sources of key pests and diseases in and around the farm and being aware of the risk factors.

Thrips, mites and whiteflies are common pests that are far more readily managed when routine monitoring is used to identify early incursions and likely sources. Recognising the early signs of diseases are important and regularly checking a sample of plants in every greenhouse gives a grower the capacity to pre-empt outbreaks and ensure appropriate hygiene practices are being followed.

PH&G: Since the HAL fact sheets were published, have there been any updates growers should know of?
JBP: No, though it is worth noting that the fact sheets are available online. There is also a farm review workbook plus an order form for a copy of the manual [see below].

Request your copy of Keep it CLEAN
Keep it CLEAN is a comprehensive guide for greenhouse growers that lists and describes more than 70 management practices that can significantly reduce the costs and losses that can result from pests and diseases.

The guide also includes practical information on key pests and diseases, assessing the risk of different problems, conducting simple pest and disease monitoring and developing action plans to implement new management practices.

For your copy of Keep it CLEAN – published by NSW Department of Primary Industries – go online: or email:

The guide (normally $33 incl. GST) is available FREE of charge to Australian vegetable-levy-paying greenhouse growers.

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