National Voluntary Farm-Level Biosecurity Standard for the Greenhouse, Nursery and Floriculture Sectors
2.0 Plant Health Management

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The implementation of an effective biosecurity plan can promote plant health. Multiple factors can individually and collectively affect the health status of a plant such as soil quality, water quality, presence of pests and environmental factors.

Figure 3: The Plant Pest Triangle

Figure 3: The Plant Pest Triangle. Description follows.
Description for Figure 3: The Plant Pest Triangle

The Plant Pest Triangle has a triangle with the words "Incidence and/or severity of pest occurrence" written on it. Each point of the triangle has a circle surrounding it. Starting at the top, the first circle says: Crop. To the right, the second circle says: Environment. To the left, the third circle says: Pest.

Figure 3 illustrates the relationship between a pest, the environment, and the crop. Pest outbreaks do not happen in isolation, they are dependent upon the interrelated nature of these three factors. The Plant Pest Triangle shows that the incidence and severity of an outbreak relates to the interaction of a susceptible crop, a pest, and an environment favourable to pest development.

Plant pests may be mitigated through the application of biosecurity measures to reduce the risks presented by these three components. Specific plant types such as tolerant varieties and management of the environment may mitigate the severity of the outbreak if a pest has been introduced.

It is recognized that it may be possible for a pest to be introduced to a place of production where a host crop is not present (for example: pests can be present in potting media). There are conditions where the environment provides favourable bridging conditions which allow for pests to survive. It is also recognized that these conditions, without the presence of a host crop, would likely allow for pest introduction, but not pest proliferation.

Plant health management includes four key areas:

  • Management practices, for example, management of crop environment to promote healthy growth (for example: crop nutrition, irrigation and greenhouse climate);
  • Management of pest vectors;
  • Pest monitoring to detect and quantify pests; and
  • Responding to a pest with an Integrated Pest Management (IPM) program for commonly encountered pests or response planning for pests of greater concern, such as quarantine pests.

2.1 Management Practices

Target Outcome:

The combination of Best Management Practices and the implementation of biosecurity measures optimize the production of healthy plants.

Benefits: Best Management Practices (BMPs) that optimize production may promote the growth or introduction of pests. Complementing BMPs with biosecurity measures can optimize production of healthy plants.

Considerations

Internal and external environment

  • It is recognized that intentional or managed plant stress (such as generative/vegetative production or hardening off) can be a tool for production. However, plant stress can increase plant susceptibility to pests resulting in an increase in the severity of damage.
  • Environmental stress, such as frost damage or water stress can also increase crop susceptibility to pest attacks and the severity of pest impact. Reducing plant stress by maintaining optimal environmental controls and protecting against inclement weather can minimize pest outbreaks.
  • 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 (fungus or mold). In these situations where growing conditions may create risks, counter measures such as increased airflow or increased plant spacing should be considered to minimize potential outbreaks.
  • Establishing a weed-free buffer around the place of production or crop and maintaining the area surrounding a production area (for example: regular mowing) may reduce the risk of pest introduction from weeds.
  • Physical injury to plants from equipment, pruning or environmental conditions (for example: hail, frost and heavy rains) can make the plant more vulnerable to pest attacks and damage.

Nutrients, growing media and water management

  • Ensure that an adequate fertilizer program is in place, as nutrient deficient or over-fertilized plants are more vulnerable to pests.
  • Crop rotation may be used to disrupt the lifecycle of pests.
  • Soil and growing media may contain pests. If a pest is present in the soil or growing media at a threshold that may cause damage to plants, then treatment of the soil or growing media may be necessary prior to planting. Treatment options include heat pasteurization, solarization or fumigation.
  • Water quality and quantity may impact the health of a plant and increase vulnerability to pests. Scheduled testing of water for pathogens, nutrient levels, pH and salt level will identify potential issues that may impact the health of plants.
  • If recycling water, it is recommended that a treatment system be considered.
  • Different types of irrigation systems such as flood, drip, hydroponics, and overhead irrigation pose different plant health management concerns. Become familiar with common problems posed by the type of irrigation system of the place of production.

Plant material selection

  • When possible, choose pest tolerant varieties or cultivars.
  • Recognize there are different pest risks associated with different sources of plant material.

Crop protection products and approaches for commonly occurring pests

  • Implement an Integrated Pest Management (IPM) program. IPM is a decision-making process that takes many factors into account when deciding upon a treatment.
  • Be aware of secondary impacts of actions that are taken to treat pest pressures. For example, chemical pesticides can cause phytotoxicity and harm biological controls. There can also be negative interactions between biological controls. Detailed records of all treatments applied and responses of pests and natural enemies can help identify conflicts. Impacts of insecticides on insect natural enemies can be researched on online databases before application.
  • Pest thresholdsFootnote 3 for non-regulated pests may be established to trigger the use of a particular 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.
  • Develop a pesticide resistance management strategyFootnote 4. Pesticides in different chemical classesFootnote 5 should be regularly rotated to avoid developing a pesticide-resistant pest population. Pests on imported plants or cuttings may already be resistant to pesticides used in Canada. Obtain the details from the supplier of the chemical program used on any imported material to inform IPM decisions.
  • Co-mingling of new plants or product coming into the place of production with older material and mother stock should be avoided. Production and the flow of propagative material and plants within a place of production should move in one direction only.
  • Activities on neighbouring farms such as harvesting may increase the risk of pests entering a greenhouse through vents or other openings. When this occurs additional methods of pest control may need to be considered, such as prophylactic release of biological control agents, or the use of pesticides or mechanical controls (for example: mass trapping).

2.2 Pest Vectors

Target Outcome:

Implementation of biosecurity measures at critical points in pathways of pest transmission.

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. Pathways of pest transmission include:

  • Biological vectors such as insects, birds, mammals and workers within the place of production
  • Physical vectors such as packing materials and equipment
  • Environmental vectors such as wind and surface water

Considerations:

  • Inspect all inputs (new plants, propagative material, and packing material) for the presence of pests prior to accepting or moving the materials onto or within the place of production, if possible. Insects may be more visible than diseases.
  • Receive, inspect and store inputs in a designated area away from production areas to prevent introduction and spread of pests to plants.
  • All new plants or propagative material should be placed in isolation for a period of time to monitor and identify pests that may be present. This is important for places of production where mother plants are a part of the production cycle. If isolation is not possible, other options such as increased monitoring may be considered.
  • If unfamiliar with the source of material, greater importance should be placed on segregating and inspecting the material thoroughly for pests.
  • Insects may act as vectors for pests of concern and this risk should be considered in an Integrated Pest Management (IPM) program.

2.3 Pest Monitoring

Target Outcome:

Minimize production losses through the early detection of pests.

Benefits: The development and implementation of a monitoring program allows for the detection of new and common pests. Monitoring is essential to determine when pests are about to reach a threshold and control measures should be implemented. A routine monitoring program will also allow for the assessment of the effectiveness of control measures, production practices and treatments. Routine monitoring includes inspection of new plants when they arrive at the place of production and of plants in production.

Considerations:

  • It is recommended that a monitoring program be developed which highlights susceptible times in the production cycle (for example: flowering), or periods where control options are more likely to be successful or cost effective.
  • Monitoring can be both informal and formal. Informal monitoring is constant and undertaken to detect pests. Formal monitoring is a planned systematic process to detect and quantify pests. This information is used to decide when to implement control measures. Both types of monitoring may be included in a monitoring program.
  • Maintain records of monitoring activities, especially pest finds. Records can be used in future years to predict times of high risk. Elements to be recorded might include location, date, crop type, control strategy implemented and the success of this strategy.
  • Educate employees in the identification and symptoms of pests. Consider providing pest fact sheets or information sheets that explain how to identify pests of concern. See section 4.0 for further information on the importance of training and communication elements of a biosecurity plan.
  • Employees are informed of the process to report pest detections.

2.4 Responding to a Pest

Target Outcome:

An Integrated Pest Management (IPM) program is developed to respond to common pests. Formal response plans are created for pests of greater concern.

Benefits: When a pest is detected there is a decision making process that involves analysis to determine if a response is required, the timing of the response as well as the identification of the most appropriate control. When a pest is found, control actions may not always be required as not all pests carry the same risk. Creating an Integrated Pest Management (IPM) program and formal response plans involves analyzing the pest risk to determine the level of response required. Preparing detailed response plans or procedures prior to the identification of a pest may facilitate an effective and timely response which may reduce production losses.

Considerations:

Unregulated pests

  • When an unknown pest is detected, preserve a sample to allow for accurate identification.
  • Infested material should not be mixed or come in contact with other product to limit the spread of a pest.
  • Prepare an IPM program that describes a process to quickly build a situation-specific response to a pest find. The process should include confirmation of pest identification as well as determination of pest risk and control measures.
  • For unknown pests, use laboratories, extension specialists, consultants, researchers and the Canadian Food Inspection Agency (CFIA) for confirmation of pest identification.
  • Enhanced monitoring may be necessary when a pest has been found to quantify the level of infestation or assess the effectiveness of applied control measures.
  • Pests introduced to a place of production through imported plants or cuttings may already be resistant to pesticides available in Canada. When resistance is encountered, alternative control methods such as biological control may be considered.
  • Periodically evaluate the effectiveness of the pest management plan to foster continuous improvement and efficiencies.

Regulated Pests

  • When a regulated pestFootnote 6 is identified, the CFIA and the respective provincial or territorial government must be contacted to report the detection. In the response plan include the contact information of the local CFIA office, provincial extension specialists and sector association(s).
  • If the detection of a regulated pest is suspected, limit the potential spread of the pest through the control or restriction of movement of plant material as well as people and equipment in and out of the infected area.
  • Periodically evaluate the effectiveness of the response plan to foster continuous improvement and efficiencies.
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