Crop Production News 2018 - Issue #2
By Saskatchewan Ministry of Agriculture
Biosecurity is something that is widely used in the livestock industry, but is still a relatively new concept in the grain industry. Recently, the conversation around biosecurity has been centred on the prevention of clubroot, and that is the focus of this article, but it is important to note that these practices can be used to prevent the introduction of other diseases, weeds and insects.
Many disease-causing pathogens overwinter on infected seed, on residue or in the soil, and can be spread to new areas or new fields where it may not already exist through the movement of infested soil or plant materials. Even if the disease-causing pathogen is already present within a field, biosecurity measures can be used to prevent the introduction of new races or pathotypes of the pathogen that may be more aggressive and difficult to control.
For clubroot prevention, the focus should be on preventing the movement of infested soil through any activity conducted on agricultural land. Not all activities have the same level of risk. Activities that move large volumes of soil and activities that move soil directly from clubroot-infested areas are considered to have the highest risk. The biosecurity requirements required will vary depending on the risk.
On the farm, complete sanitation of equipment will not be always be practical or required. Below are some practical recommendations that can be used to minimize the risk of introducing clubroot or other crop pests when working in fields.
- When possible, avoid working in wet or muddy conditions. When fields are wet, higher volumes of soil can be moved on equipment and cleaning will be more difficult;
- Take the time to knock as much soil off as possible between fields. Even if you only have 10 to 15 minutes between fields, something is better than nothing. Remember that if you remove 90 per cent of the soil, you are reducing your risk by 90 per cent;
- If clubroot is known or suspected to occur in a field, always visit that field last and clean your equipment before working in other fields;
- Fully sanitize all new equipment, particularly if you purchased it from an area with or suspected to have clubroot. This involves pressure washing or using compressed air to remove all soil particles and applying a disinfectant (two per cent sodium hypochlorite) and letting it remain on the surface for 20 to 30 minutes;
- Create a separate exit as far as possible from the field entrance;
- Consider posting multiple “no trespassing” signs to minimize unauthorized vehicles;
- Restrict the entry of vehicles unless they have been properly cleaned; and
- Talk openly about your biosecurity expectations with all individuals who are working on or have access to your land.
Agronomists and others working on agricultural land also have a risk of moving clubroot. This risk increases when working on multiple farms over a large geographic area. Many of the recommended practices will be similar to those mentioned above. When possible, avoid driving into a field and instead walk into the field to complete your work. The “Crop Disease and Invasive Species Biosecurity Protocol” infographic describes the recommended practices for different types of field activity according to the associated risk.
When completing field work as an agronomist, it is a good idea to have a biosecurity kit on hand. The following items should be included:
- Disposable boot covers;
- Rubber boots and a scrub brush to remove soil if disposable boot covers are not used.
- To make cleaning simpler, get a plastic container to fill part way with your disinfectant. In the lid, cut two holes so that you can slip the top of your boots through.
- After working in the field, remove your rubber boots and switch shoes, scrub the soil off of the boots and place them in the container in the back of your vehicle.
- This way they can sit in the disinfectant between fields without making you wait 20 to 30 minutes;
- A disinfectant solution of two per cent sodium hypochlorite. Sodium hypochlorite is the active ingredient in bleach and is the most effective disinfectant. Virkon® has been found to be only moderately effective in reducing the viability of the clubroot pathogen.
- Bleach products range in the concentration of sodium hypochlorite and typically contain between four and eight per cent. As a result, different dilutions will be required for different bleach products to make a two per cent solution.
- For example, Clorox disinfecting bleach® contains six per cent sodium hypochlorite. To make a 750 mL of a two per cent solution, you will have to add 250 mL bleach and 500 mL water;
- Hand cleaning wipes and paper towel; and
- Garbage bags to collect used wipes and boot covers.