Upcoming Events/Perennia Updates
A new 2-part webinar series on greenhouse biosecurity has come across my desk! I've pasted the session description and the registration link for those of you who are interested:
Session dates:
March 24: 7-9 pm
March 31: 7-9 pm
Session description:
Attention Growers—Big or Small! Ready to enhance your biosecurity and safeguard your operation? Join our free two-part webinar series, based on the National Farm-Level Biosecurity Planning Guide for the Greenhouse, Nursery, and Floriculture Sectors. These interactive sessions will help you understand biosecurity’s importance and adopt strategies to protect your operation—whether you're a small business or managing a larger greenhouse, nursery, or floriculture operation.
With 4 hours of expert-led learning on the Zoom platform, you’ll hear from Kelly Smith and get answers to your specific questions. Active participation in both sessions is required to earn a Certificate of Completion. I'll email registered participants a week before the first webinar with details to help you prepare.
Questions? Contact Jenn Nash, Field Representative, at 705-991-3909 or jnash@ontariosoilcrop.org.
The virtual workshop has capacity for 25 participants, so if you are interested, be sure to get yourself on the list sooner rather than later.
Registration link: OSCIA Workshops Portal
Recent Project Work: Assessing the Feasibility of Anaerobic Soil Disinfestation in Nova Scotia
Anaerobic soil disinfestation (ASD) is a low-cost, accessible process which was developed in the Netherlands and Japan. It is commonly used in the U.S. as an effective, microbial-based method for controlling soil-borne pathogens, nematodes and weeds. The process requires low inputs and minimal intervention, reducing on-farm management costs.
Working with Horticulture Nova Scotia, we were able to implement a 2-year project assessing the success of on-farm implementation of ASD in high tunnels in Nova Scotia. Understanding the
success rate of the process and finding the ideal timing for implementation will be the
focus of the program, as well as assessing the cost of implementation. Interruptions to greenhouse production are not
taken lightly in these high value spaces, so understanding how much time is
required for different times of year will be an important variable for on-farm
adoption in the future.
This blog post will address the three main objectives to the project. For background information and implementation specifics, check out the webinar I hosted with Anna Teston from the USDA a few years ago. The information presented in this webinar was what we used to base our amendment application rates on.
Supply list:
- 4.5 tons/acre of molasses
- 9 tons/acre of our main carbon source (target C:N ratio for this amendment is 18:1)
- Incorporation equipment
- Water
- Plastic
- Sandbags
Both participating farms opted to use year-old chicken manure from their farms as our main amendment. This was supplemented with organic sugar, as a substitute to molasses. This decision was made primarily based on price/accessibility to certified organic products. A significant benefit to this decision, however, was that application was much easier, compared to spreading molasses in a high tunnel soil on a hot summer day.
Target molasses application was 4.5 tons, or 9000 lbs, per acre. Running off the assumption that the average sugar content of molasses is 46%, 9000 lbs of molasses contains 4,140lbs sugar/acre.
Project Objectives:
1) Assess the efficacy of anaerobic soil disinfestation in Nova Scotia
Anaerobic soil disinfestation has been documented to reduce nematode, disease, and certain weed pressures on farm. Our goal with the project was to see whether these benefits were realized on Nova Scotia farms.
Nematodes
We wanted to get a sense of how effective ASD is at reducing nematode populations. Samples were taken in the spring and fall, correlating to pre- and post- implementation. Here's what we found:
Pre-ASD Spring Sampling | RLN/100cc soil | Pin/100cc soil | Spiral/100cc soil | Cyst/100cc soil |
Trial Area (Farm #1) | 19 | 2 | 2 | 2 |
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Post-ASD Fall Sampling | RLN/100cc soil | Pin/100cc soil | Spiral/100cc soil | Sheath/100cc soil |
Treatment Area (Farm #1) | 3 | 0 | 0 | 1 |
Control (Farm #1) | 43 | 4 | 1 | 0 |
*RLN = Root lesion nematode
There was a notable reduction in plant parasitic nematode counts observed via sampling. Root lesion nematode saw the greatest reduction from the pre-ASD sampling to post-ASD sampling in the treatment area. For the control area in the high tunnel that did not receive ASD, we can see that the nematode population count was quite a bit higher.
These results were strengthened through observations of nematode damage in a carrot crop that was planted immediately following the trial. Carrots that were planted in a bed that had been treated had a significant reduction in damage, compared to carrots that were planted in the control bed that did not receive treatment.
Pre-ASD Spring Sampling | RLN/100cc soil | Spiral/100cc soil | |
Trial Area (Farm #2) | 3 | 71 | |
Post-ASD Fall Sampling | RLN/100cc soil | Spiral/100cc soil | Stunt/100cc soil |
Treatment (Farm #2) | 1 | 48 | 1 |
Control (Farm #2) | 13 | 36 | 1 |
*RLN = Root lesion nematode
On the second participating farm, a decrease in nematode pressure was also observed, however pressure from spiral nematode remained present post treatment.
Disease
The strategy to assess disease pressure was to collect soil samples from our participating farms before and after implementing ASD. Soils were frozen and then used to germinate disease-susceptible tomato seedlings in. These seedlings then serve as an indication of whether the disease pressure in the soil was lower, higher, or stayed the same compared to the pathogen profile in the pre-ASD soils. This also allows us to tease apart difference in production that may have been noticed- was the added fertility and stimulation of microbial communities the reason our plants are growing better? Or is it because we had a reduction in disease causal agents?
Figure 2. Tomato seedlings grown in a soil that received ASD under the 'Post-ASD Treated' label. Photo credit: Talia Plaskett
In figure 2, we can see the results of our disease assay. Plants were seeded into a soil that has received the amendments (aged poultry manure, organic sugar) and were exposed to anaerobic conditions and the target temperature for 4 weeks. Of the 5 plants that germinated, three of them are showing signs of damping off, indicating that the process was not successful at eliminating disease.
One of the participating farms reported a higher than usual degree of damping off observed in the winter greens planted in the treated area compared to what they typically observe. This could be the result of reduced microbial competition for root diseases like Pythium, making it easier to come in and infect vulnerable plantings. A year and a half later, they are able to use the soils no problem.
The other farm, however, reported that the fusarium and blight seem to have been knocked back in the treated areas, so it could come down to the disease that we are dealing with as to whether or not this method makes sense for you.
Insect Pests
One farm reported reduced winter cutworm damage on greens following the process, and less wireworm damage as well.
Weeds
In terms of weeds, the chickweed population remained healthy following ASD, so it was not effective at reducing their weed population in this greenhouse.
Other Noteworthy Comments
Both farms reported that the soil quality was well improved following ASD - It comes out with a beautiful tilth following the addition of our amendments, moisture, tilling, and allowing it to sit for a few weeks. There may have been a bit of compaction following the process, but once the soil was worked, it had a really lovely quality to it.
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In case you missed our summer field day on site in July of 2025, David Blanchard of Pleasant Hill Farms spoke about the results of ASD on their farm in the February 2026 Tunneltalk webinar focused on integrated pest management. You can access the recording of that session here. He was the last of three speakers in the session.
2) Conduct a cost analysis for the process
The average cost of supplies for conducing ASD was $974.73. The bulk of that cost was the tarps needed to create anaerobic conditions. Organic sugar was about a third of that cost, and the on-farm chicken manure was valued around $100.
Figure 3. A high tunnel undergoing anaerobic soil disinfestation. Photo credit: Pleasant Hill Farms.
for one greenhouse, it took 4 people about 3.5 hours to weigh and spread amendments, incorporate w machinery, and dig a soil trench around the area to be treated so that the tarp could be sufficiently buried. Once the Perennia crew left, soils were left to soak for a few hours using sprinklers, and then a tarp was used to cover the area, and the edges buried.
for one small field plot, it took 6 people about 4 hours to weigh and spread amendments, incorporate about half with a tractor (the rest had to be hand-incorporated), and dig a soil trench around the area. The area was then left to soak, and the tarp dragged out and buried along the edges.
3) Identify the timing feasibility for ASD in Nova Scotia
Feasibility was one of the driving factors for wanting to trial on-farm implementation. The process requires 3-4 weeks with a sustained 15C soil temperature, which is difficult to accommodate in our short growing seasons. Based on the work done in the US, spring and fall implementation seemed to be the most popular time frame, however I wasn't sure if we would be able to generate enough temperature in those windows in Nova Scotia for the process to be effective. This window also significantly cuts into our winter and summer crops. For high tunnel producers, where there isn't the option to 'grow the crop somewhere else', this requires the sacrifice of high value space in order to prioritize the management of disease, weed and pest pressure.
One of the project participants was eager to implement ASD in a high tunnel in the spring. The goal was to have the soil ready for tomato transplants at the end of April/early May. The beds were prepped, amendments added, and plastic laid down in middle of March. There were about 4 weeks of time set aside for the process. We installed two soil temperature sensors, which are represented in blue and orange in the graph below (Figure 4). The dark green line represents our target temperature for successful ASD.
Despite warm air temperatures that were consistently 20C+ during the day for this period, our soil temperatures remain quite a bit lower. We only breach our target temperature as of April 19 in this case, meaning we were not successful at kickstarting the microbial processes required to see the benefits. If this were to be used as any kind of bench mark, we aren't going to be able to see implementation of this process until the end of April. Tack on the required 4 weeks, and our tomatoes are not able to be planted into the high tunnel until early June. This is in line with when we would typically see seedlings transplanted outdoors, so any advantage of season extension using a high tunnel would be lost. Yes, there is seasonal variation year to year, but I don't think enough that would allow you to get a head start on field plantings of cash crops.
Using this information, both farms decided to tackle an ASD implementation during the peak summer months. For operators who are looking to maximize winter and shoulder season production, this allows for a full season of spring crops, and has the soil ready for fall planting. Treated areas were equipped with soil temperature sensors so that we could track how things were tracking through the peak season. In the graph below (Figure 5), we can see the temperature information collected using two sensors. The orange line was buried deeper in the soil (approximately 12-16 inches) compared to the blue line which was closer to the surface, and therefore more prone to being influenced by the air temperature. The green line represents the minimum temperature we are looking to maintain throughout the duration of the trial.
Based on this information, we can see that hitting and maintaining our target temperature was no problem from August 20 - September 17. You will notice however though as we get into September, the lines of the vertical bars representing the high and low for each day, are starting to dip below our target 15C.
While we didn't play around with a fall implementation, I don't think there is necessarily an advantage there. If we infer that soil temperature drops below 15 degrees around September 30 (a generous extension of the temperature data displayed in figure 4), that means we would need to have our ASD protocol installed 4 weeks before that in the first week of September. Our summer cash crops would have to be terminated mid to late August in order for us to prep the soil for the process and clean things up. For high tunnel tomatoes at least, this is when things are really getting going. We know that there are still two good months of harvesting that would be lost if we were to terminate late August, causing a significant disruption to our cash flow.
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SUMMARY
All in all, here is the short version of the results summarized above:
1) ASD showed to be an effective way to reduce nematode populations. Disease and insect reports were varied, and weed pressure was not impacted by the treatment. The success of ASD implementation on your farm will be highly dependent on the pest/disease pressure you are looking to tackle.
2) Average cost to implement ASD was $975 CAD, not including labour or the time the space is out of commission for the generation of cash crops.
3) While the process is feasible in Nova Scotia, I would not recommend investing time, energy and lost cash crop revenue in a shoulder season implementation. Based on our small subset of data, end of April to the beginning of September would be the target for starting ASD, with no guarantee of success depending on the year. The deeper into the summer you decide to start, the better your chances are of sustaining a soil temperature of 15C.
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Due to the varied/discouraging disease assay results, we decided to take some of the project funding and use it to explore other tools we have to reduce disease pressure on high tunnel tomatoes. We executed two trials where we evaluated the efficacy of different biological root protectants against tomatoes inoculated with Pythium root rot. I will do a full summary of that work at the end of March, so stay tuned!
