Greenhouse Vegetable Sector Biosecurity Guide
2.0 Plant Health Management

2.1 Management Practices

Benefits: Best management practices that optimize production may also create an optimal environment for pests. Complementing best management practices with biosecurity measures can help manage the risk of pest introduction and spread.

Risks

External environment

Weeds and volunteer plants can be a source of pests and should be controlled both in and around the place of production. A well-maintained weed-free zone around the place of production may help prevent pests from entering.

In addition to weeds, organic debris such as rotten vegetables can also be pest vectors. Organic debris should not accumulate in a place of production but be disposed of promptly in a designated location away from the place of production in a manner that minimizes potential pest spread. If necessary, biosecurity measures such as deep burial may be implemented to mitigate the re-infestation of other crops.

Internal environment

Maintaining a clean place of production may minimize the introduction and spread of pests. This includes cleaning the packing house in addition to the production area.

Baskets containing banker or indicator plants may be used in a place of production as part of the Integrated Pest Management (IPM) program. However, as in the case of weeds, ornamental and decorative plants can also be a source of pests.

Growing conditions should be managed to support crop growth while minimizing the crop's susceptibility to pest attack. Growing conditions such as high humidity can promote the establishment of some pests such as fungus or mould. In situations where growing conditions may create risks, management practices such as increased airflow or increased plant spacing may be considered to minimize potential outbreaks. In addition, consulting with a specialist may provide further recommendations regarding the appropriate measures to be applied.

Crop removal can present a risk of pest spread within a place of production. Depending on the production schedule, crops can be replaced at the end of their production season, or in some cases pests may require the crop to be terminated early. The removal process can happen in different ways, as there can be three cropping methods in practice in a place of production:

1. Mono-cropping: The entire crop is removed prior to planting the new crop.
2. Continual cropping: Sections of the production area are removed and replaced while other crops are still in production.
3. Intercropping: The replacement crop is grown in the same place and phases out the old crop. Managing the risks of pest spread during crop removal is more critical in this method of production.

Measures should be taken to avoid or minimize the spread of pests to the new crop or other crops during the pulling-out process. The mono-cropping method removes the entire crop prior to planting the new crop. This is the easiest method to reduce pest spread to the new crop. With continual cropping and intercropping, there is no break in the pest cycle if a pest is present. There is also an increased risk of pest spread to other crops being grown in the place of production. For all three cropping methods, biosecurity measures should be considered throughout the cropping cycle and while removing infested material to mitigate pest spread.

After the old or infested crop is removed, the place of production should be thoroughly cleaned and disinfected to ensure no organic debris remains. Attention should be given to difficult-to-reach areas, such as corners, structural components, crop wires, irrigation tubing or roof trusses.

Nutrients, growing media and water management

Water can be a pest vector. When water is sourced from re-circulation water, ponds, streams or other surface water sources it should be disinfected as required. Water disinfection equipment includes heat, ultra-violet (UV) radiation, ozone, and filtration. Growing media and nutrients from organic sources may contain pests and should be purchased from a reputable supplier.

Imported product, plant material and seed selection

Imported and domestically sourced product for packing and repacking, seeds and plant materials are important pathways through which pests are introduced to a place of production. Pests can be found on the surfaces and/or inside of the product, seeds and plant materials. These inputs should be purchased from a source that has biosecurity measures in place to prevent the introduction and spread of pests. As well, these and all inputs should be inspected before they are accepted into the place of production.

Crop protection products and approaches for commonly occurring pests

Pests can be introduced into the place of production by a variety of vectors. Insects can be a vector for viruses, bacteria, fungal spores, and mites. For example, shore flies and fungus gnats can vector spores of the fungi Fusarium and Pythium, and cucumber beetles can vector cucumber wilt bacteria. Controlling insect populations may limit the spread and damage from insect-vectored pests.

Pest thresholds^Footnote 1 for non-regulated pests may be established to trigger the use of a treatment. It should be recognized that what constitutes a threshold is complex, as there are different thresholds for different crops and pests. Within the decision of thresholds for treatment there is a difference between suppression, eradication and management.

Management Practices Self-Assessment Checklist

2.2 Pest Vectors

Benefits: Managing vectors and interrupting the pathways of pest transmission can reduce crop damage and minimize economic losses. The implementation of proactive biosecurity measures can mitigate the potential for introduction and spread of pests if applied to a critical point in a pathway of transmission. Examples of pathways of pest transmission include insects, people and wind.

Risks

Pests can often be spread or introduced into a place of production by more than one vector. For example, whiteflies can disperse through flight, but can travel much greater distances when carried by wind; mobile fungal spores can move much farther when carried by irrigation water.

Another example is thrips, which can be introduced into a place of production through vents and doors by wind. Once they have been introduced into a place of production, thrips can spread viruses throughout the production area and can be spread from one production area to another by growing media, equipment and employees. Biosecurity measures such as an Integrated Pest Management (IPM) program that includes mitigation measures for insects can help to prevent the spread of pests in the place of production.

There is a risk of pest introduction and spread from all inputs that enter the various areas in the place of production, especially those from external sources. For example, inputs such as product for packing and re-packing can present a risk of pest introduction into the packing house. Inputs such as transplants, growing media and seeds present a pest risk to production areas. To mitigate these risks, inputs should be inspected upon entry into the place of production and prior to use. To help with these inspections employees should be given pest identification training. In addition, pictures of pests can be posted in the areas of the place of production where inputs are received and inspected to help with the identification of pests. Please refer to section 3.4 Production Inputs for further information regarding the risks of inputs.

Production Area

Seeds can be hosts of pests such as viruses and bacterial cankers. This is especially true for tomato seed. As these pests will not be visible during an inspection, seeds should be purchased from a supplier that can provide a certificate to state the seeds are pest free. Once the seeds are received by the place of production, a percentage of the seeds may be tested to verify freedom from pests.

Growing media may contain pests and should be purchased from a reputable supplier. Growing media should be inspected upon arrival for pests and if a pest is present, treatment may be necessary prior to use. Treatment options include heat pasteurization, solarization or fumigation.

When purchasing transplants, it may be possible in some regions to inspect the material for pests at the propagator's place of production. In other regions transplants should be inspected upon entry into the receiving area of the place of production.

Packing House

Packing and re-packing product from foreign or domestic sources should be thoroughly inspected for pests once it arrives at the packing house and during repacking.

Production Area and Packing House

People, vehicles and equipment can also be a pest vector. Footbaths, disposable coveralls and footwear can be used to mitigate the introduction and spread of pests by people. Cleaning and removing organic debris can help mitigate pest introduction and spread by vehicles and equipment. Please refer to section 3.3 Movement of People, Vehicles and Equipment for further information regarding biosecurity measures that may be applied to mitigate pest introduction and spread by people.

2.3 Pest Monitoring

Benefits: The development and implementation of monitoring and scouting programs allows for the detection of new and common pests. A monitoring program includes the inspection of material such as new plants when they arrive at the place of production and a scouting program includes the inspection of plants in production for pests. A scouting program will help determine when pests are about to reach a threshold. A routine scouting program will also allow for the effectiveness of control measures, production practices and treatments to be assessed.

Risks

Production Area

A scouting program may use a scout or crop consultant to regularly inspect the crop for pests and determine whether pest thresholds have been reached. Records of the results should be kept, detailing the location, the origin of the plants and the severity of each pest found.

A scouting program may also highlight specific times in the production cycle or periods where control options are more likely to be successful or cost-effective. For example, scouting may be increased during times of harvest on neighbouring farms as this may increase the potential for the introduction of thrips into the production area. Another example is in the fall when the population of winged female aphids increases on outdoor crops. This may increase the risk of aphids entering into a production area through vents or doors and increase the potential for these aphids to introduce viruses such as Cucumber mosaic virus (CMV).

Devices such as sticky cards or pheromone traps may also be distributed through the crop to detect insects. Additionally, ultra-violet (UV) lights can be used to attract a wide range of insects, particularly during cooler months.

Packing House

Monitoring devices such as sticky cards can be used to detect pests in the packing house. These devices can be placed near the packing machine and in areas where imported and domestically sourced product is stored. Devices should also be installed around loading docks and doors where product is brought inside the packing house.

Production Area and Packing House

Employees working in both the production area and packing house should be trained in the identification of the most common pests. Pest fact sheets and posters of pests in the break area and lunchroom can help educate employees to identify pests. Appendix 1 is an example of a pest fact sheet. Contact consultants, Integrated Pest Management (IPM) specialists, sector associations or provincial extension specialists to obtain pest identification posters.

In addition, employees should also be trained on how to report a new pest identified in the place of production.

Pest Monitoring Self-Assessment Checklist

2.4 Responding to a Pest

Benefits: When a pest is detected, there is a decision-making process to determine if a pest is past the threshold, if a response is required, the timing of the response and the identification of the most appropriate control actions. Depending on the pest that is detected and its threshold level, control actions may not always be required as not all pests carry the same risk. Pests regulated by Canada have a zero-tolerance threshold and a requirement to report the pest detection. Even pests that are not regulated may have a zero-tolerance or a low threshold if they are of significant economic concern to producers. For example, a producer may have a zero-tolerance threshold for a pest that is regulated by a country with an important export market. Creating an Integrated Pest Management (IPM) program and response plans involves analyzing the pest risk to determine the level of response required, and at what threshold a response is required. Preparing detailed response plans or procedures prior to the identification of a pest may allow an effective and timely response which may reduce production losses.

Risks

Regulated Pests

The Canadian Food Inspection Agency (CFIA) maintains the list of pests regulated in Canada, which includes insects, mites, molluscs, nematodes, fungi, bacteria, viruses, phytoplasma and some parasitic plants. When a regulated pest^Footnote 2 is identified, the CFIA and the respective provincial or territorial government must be contacted to report the detection.

A response plan for a regulated pest should include the contact information of the local CFIA office, provincial extension specialists and sector association(s). The response plan should include biosecurity measures to prevent the spread of pests from the infested area by restricting the movement of plant material, people and equipment in and out of the area. Please refer to section 3.2 Biosecurity Zones for biosecurity measures to mitigate the spread of pests from Restricted Access Zones (RAZ).

Non-regulated Pests

The IPM program for a place of production should include a response plan for the detection of a pest. A response plan may include the following steps:

• Confirming pest identification.
• Determining pest risk.
• Determining the pest threshold and whether it has been exceeded.
• Applying control measures, if required.
• Restricting movement of plant material, crops, people and equipment into and out of the infested area.
• Cleaning of footwear, hands and equipment leaving the infested area.
• Evaluating the control measures and response plan.

Pest thresholds^Footnote 3 for non-regulated pests may be established to trigger the use of a treatment. It should be recognized that what constitutes a threshold is complex, as there are different thresholds for different crops and pests. Within the decision of thresholds for treatment there is a difference between suppression, eradication, and management.

The response plan should also include biosecurity measures to prevent the re-infestation of crops by infested material. To limit pest spread, infested material should not be mixed or come into contact with other crops, and should be securely disposed of away from the place of production or buried. Please refer to section 2.1 Management Practices: Internal Environment and section 3.5 Production Outputs for biosecurity measures related to disposal.

Keep records of the location, date and crop type of the infested material and the control measures that were applied. This information may be useful to assess the success of the response strategy and for continuous improvement to the response plan.

Regulated and Non-regulated Pests

For both regulated and non-regulated pests the effectiveness of the response plan should be evaluated periodically to foster continuous improvement and efficiencies.

Pest Response Self-Assessement Checklist