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The horticultural sector is under increasing pressure from disease and insect pests. There are many ways that growers deal with pests:
- Biosecurity to prevent the accidental transfer (by human activity) of a pest into a new area;
- Horticultural practices, such as pruning to ensure open tree architecture to allow sunlight penetration and air circulation to reduce disease problems;
- Use of models that predict the stages of pest development (degree day models) to better monitor pests and target pest controls;
- Scouting and trapping to monitor pest presence and pest populations, including the use of sentinel crops;
- Improving tree health with nutrients, assessing irrigation to ensure there is no water stress, and building soil health both for nutrition and to reduce root-damaging nematodes;
- Use of mass trapping, including the use of trap crops that are more attractive to pests and then the focus of more intensive controls;
- Use of biological controls, such as use of sterile insect technology, pheromones, Bt sprays, and introducing and encouraging the establishment of predators of pests;
- Chemical crop protection products, both organic and non-organic.
With all of these tools, producers still have trouble controlling pests in orchards. At a recent (2017) Area-Wide Pest Management meeting organized by Summerland Research and Development Centre, one of the main conclusions was to look at pests holistically, which means not relying on any one control method, and being aware of integrated pest management principles. We need to do better.
The increasing complexity of managing new pests or new pest problems, includes:
- Newly introduced pests (e.g. Brown Marmorated Stink Bug).
- Pests that become resistant to pesticides (e.g. apple scab).
- A reduced number of pesticides leading to problems with resistance to the remaining pesticides (e.g. Spotted Wing Drosophila).
These problems are complex and again need a holistic approach, such as looking ahead with a season-long plan for control of Spotted Wing Drosophila that takes into account the Pre-Harvest Interval requirements, as well as international Maximum Residue Limits. Handling emerging pest problems relies on advance planning and more collaborative effort is needed, so that the tree fruit industry can ensure all producers are meeting market standards. If one fails it hurts us all.
At the 2017 Area-Wide Pest Management workshop, Dr. Paul Abrams noted “the principal of total population management (Knipling), as uniform suppressive pressure applied against the total population of the pest .. will achieve greater suppression than a higher level of control on most, but not all, of the population
This important principle is an extension of the Integrated Pest Management concept, where pests are controlled by
- Monitoring;
- Determination of an economic threshold (below which low pest populations cause limited damage that is acceptable and ‘in balance’ with predators;
- Treatment only when pest populations are on the economic threshold;
- Control of entry of new pests into the area.
The movement of pests between farms is difficult to control by any one grower, and uniform suppressive pressure is also difficult to attain when there are many growers who have many different ways of managing pests.
“Total Population Management” programs do exist, such as the Sterile Insect Release Program for suppression of Codling Moth. Discussions of expanding the scope of the SIR program to other pests have been held over many years, but no imminent change is anticipated. The industry and growers in particular would be consulted long before any change would possibly take place in the program.
Dr. Abrams concluded that the challenges for effective area-wide management implementation are:
- Tendency for pest control to be reactive rather than planned;
- Continued introductions of new invasive species disrupting existing programs;
- Lack of dedicated program and resources for area-wide programs for new invasive species.
However, a new federal-provincial policy and initiative provide hope, though real solutions require a lot of smart effort and resources.
The 2017 federal-provincial Animal and Plant Health Strategy provides the principles and collaborative structure to make real inroads on pest management and control of invasive pests. It identifies actions in the following four areas:
- Coordination through partnership and collaboration
- Preventative approaches to safeguard plant health
- Collection, analysis, and sharing of information
- Enabling desired behaviours
The strategy naturally has two distinct streams: animal health and plant health. To further the plant health side of the equation, the collaborators have established a Plant Health Council, established in October 2018 with a two year time horizon. The Council is developing a work plan with two to three priority activities to demonstrate the value of a coordinating council to plant health partners. Plant Health Council Working Groups have been established in the following areas:
- Surveillance: enhance activities by coordinating efforts through partnership;
- Emergency response: establish communication pathways; enhance structures and plans for effective response;
- Update current biosecurity guides and improve uptake of best practices.
Additionally, a Canadian Plant Health Network is being established that will focus on organizing events to bring together plant health specialists, environmental scanning and data storage and coordination including mapping, clean plants (propagative materials), disease diagnostics and pest surveillance, and other networking activites yet to be identified.
The opportunity to have significant improvements in pest management are apparent to the many players, but getting over the hurdles of having a great communication network and ensuring collaborative approaches were needed. Now with the new initiatives of the Plant Health Council (and its working groups) and the Canadian Plant Health Network, we have a plan to make real progress under the national Plant and Animal Health Strategy. But we will need the appropriate resources and we will need to be smart and have sustained effort to make real progress.
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