Tar spot (Phyllachora maydis) continues to be one of the most closely watched corn diseases
across the U.S. Corn Belt. This season, Spornado samplers detected airborne tar spot spores
as early as early June, providing several weeks of early warning before field symptoms
appeared.
By early to mid-July, reports began confirming the first lesions in multiple states—closely
following the environmental patterns that have defined tar spot outbreaks over the past
several seasons.

A Consistent Seasonal Trend

Across the Midwest, 2025 showed a consistent trend:

• Spores detected in early June under humid, moderate conditions.
• Visible lesions appearing 2–5 weeks later

Even when the regional trend is predictable, the exact timing in your fields can differ. Air
monitoring bridges that gap, showing precisely when spores arrive where you farm so you
can scout, plan, and spray based on what’s happening locally, not just what’s happening
across the region.

What It Means for Growers

Early signals matter. When spores are detected, scouting frequency should increase.
Spornado air monitoring provides a practical head start, often 14–30 days before symptoms
can be seen.

Weather drives pressure. Warm, humid nights and heavy dews are reliable early
indicators. Using weather modelling tools alongside spore data helps target the fields most
at risk.

Time fungicide applications carefully. Research continues to show the best results when
applications are made between VT and R3, when disease risk is confirmed and canopy
protection is most valuable.

The Takeaway

Tar spot has established itself as a recurring challenge across the Corn Belt. In 2025, early
June air detections again proved their value—allowing scouts, agronomists and growers to
stay ahead of symptoms, optimize fungicide timing, and focus resources where they count.

Spornado will continue sharing regional updates as we analyze the data from last season.

Resources

Crop Protection Network’s Tar Spot Resource Hub:
https://cropprotectionnetwork.org/publications/an-overview-of-tar-spot

Spornado Sampler: https://www.spornadosampler.com

Tar spot continues to be a growing concern for Ontario corn growers, and 2025 has been no exception. This year, the disease followed a pattern similar to previous seasons—first appearing at low levels in early July in Elgin County. Hotter, drier summer conditions kept tar spot development relatively low until August, when more favorable weather led to a late-season resurgence. With fungicide applications in place, yield losses are expected to be less severe than in recent years.

In fact, tar spot has quickly become Ontario’s most damaging corn disease. In 2024, it was the top yield-reducing disease in the province, responsible for an estimated 5.9 million bushels in losses (Crop Protection Network).

First Scouting Report vs. Spornado Early Warning

The first scouting report of tar spot in Ontario corn was on July 14, 2025, in Elgin County. This aligns closely with previous years.

But what’s remarkable is that Spornado detected tar spot spores in the air on June 19, 2025 – more than three weeks before visible disease symptoms appeared in the field. This early warning provided growers with valuable time to assess disease risk and make more informed spray decisions.

This gap between spore presence and visible symptoms demonstrates why in-field air sampling is so valuable. Tar spot often establishes before anyone sees it on leaves, meaning farmers relying on scouting alone risk detecting the disease too late to prevent losses.

Resources

For more details on tar spot development in Ontario, see the latest updates from Field Crop News and the Crop Protection Network. Both provide timely scouting reports, management strategies, and research updates to help growers stay informed.

Spornado Takeaway: Why Early Detection Matters

Spornado’s ability to detect tar spot spores weeks before symptoms appear gives growers the chance to make proactive, data-driven spray decisions. By staying ahead of disease, farmers can reduce unnecessary applications, protect yields, and improve return on investment.

California agriculture is entering a new phase in pest management. The California Department of Pesticide Regulation (DPR) is rolling out a Pesticide Prioritization Process as part of its Sustainable Pest Management (SPM) Roadmap , a move designed to reduce reliance on certain pesticide tools and accelerate adoption of lower-risk alternatives.

Read the original National Nut Grower article here: California rethinks sustainable pest management

Why This Matters

For permanent crops like almonds, pistachios, and walnuts, pest and disease control isn’t optional, it’s essential for protecting yields and profitability. But in many cases, growers depend on a small toolbox of chemistries, carefully timed to hit critical pest or pathogen windows.

Under the SPM process, some of these products could be prioritized for phase-out. That means there will be, tighter spray options, increased need for non-chemical or reduced-risk approaches, and greater pressure to prove economic feasibility of alternatives

What Growers & Agronomists Are Saying

Industry feedback, including some from the American Pistachio Growers, emphasizes that regulatory decisions must weigh economic viability alongside environmental impact, only phase out products if there are effective proven alternatives, and new strategies must be backed by research, education, and technical assistance.

Many nut growers are already using sustainable methods; mating disruption, beneficial insects, trap-based monitoring, and precision spraying, but there’s a gap: How do we know these alternatives are working in real time?

The Critical Role of Data

As the regulatory landscape changes, data becomes a grower’s best risk management tool. Specifically; Early detection of pests and diseases allows growers to avoid prophylactic sprays and only treat when necessary, Baseline monitoring across regions can guide cooperative action and help avoid surprises, Evidence-based results make it easier for regulators to approve, and for growers to trust, alternative control methods.

What We Can Do Now

Here are a few proactive steps for the 2025–2026 seasons:

1. Engaging early in DPR’s process, public input now can shape how “viable alternatives” are defined.
2. Invest in monitoring and forecasting tools to detect pest or disease pressure before it’s visible.
3. Document the impact yield, cost savings, spray reductions, or new approaches you try.
4. Collaborate regionally pests don’t respect fence lines, and coordinated monitoring reduces blind spots.

Where Spornado Fits In

At Spornado, we work with growers, researchers, and advisers to provide molecular-level early warning for airborne crop diseases. Our samplers and lab testing detects spores days to weeks before symptoms, support decision-making during spray program transitions, and help validate the effectiveness of new, lower-risk control methods.

As California moves toward sustainable pest management, we believe science-backed, grower-led data will be the bridge between policy goals and practical, profitable farming.

Using molecular diagnostics to identify fungal spores provides several benefits over traditional microscopic analysis. The main advantage is accuracy of identification and species differentiation.

Species level identification is not generally possible from a spore alone. Most spore analysts identify to the genus level only as this is all that is reliable. For example, the genus Fusarium, has 100’s of species that are very difficult to distinguish species by their spores alone. Some species cause diseases in many crops for example, Fusarium oxysporum causes Panama Disease in banana, and Fusarium Wilt in tomato, eggplants, pepper and canola.  While other species are quite specific, Fusarium graminearum causes Fusarium Head Blight in cereals. These two spores are nearly impossible to distinguish from each other under a microscope and plant pathologists routinely apply other strategies to differentiate them, such as culturing (growing out the fungi on a media plate) and molecular techniques.

Depending on the crop, incorrect diagnostics can lead to both false positives and false negatives meaning spray decisions will not be based on accurate information. By analyzing the DNA of the spores, molecular techniques can provide more reliable and definitive results.

The molecular advantage doesn’t end there. Fungicide resistance diagnostics offers the ability to assess the presence of fungicide resistant genes within fungal spores. This exciting new development for Spornado that arms growers with the knowledge to spray precisely. By knowing what you are up against, you can choose the best fungicide for the task at hand, whether it be FRAC 11 resistant mildew or FRAC 7 resistant Botrytis.

Molecular diagnostic approaches can be performed very quickly. Samples can be turned around in 24 hours from when the lab receives it. This speed is particularly crucial in situations where prompt identification is necessary for effective disease management or treatment decisions.

24/7 Sampling

At Spornado we have always believed that the longer the sample the more information you get out of it. It is widely accepted that Long-term sampling times are preferable to short-term snapshot sampling for several reasons:

Environmental conditions and fungal communities can exhibit significant variability over time. By conducting long-term sampling, you can capture fluctuations in fungal spore abundance and diversity which are known to have daily cycles and respond to acute weather events like rain. Since Spornado is sampling 24hrs a day all the variation that occurs in a day is captured.

Some fungal species may have sporadic occurrences, making them difficult to capture during short-term sampling, such as late blight. Long-term sampling increases the chances of detecting such uncommon species by providing a broader sampling window. This is particularly important when trying to catch rarely occurring diseases or those being brought in by acute weather events.

Contact us now to get molecular diagnostics and 24/7 sampling in your field.

Many significant fungal diseases that affect the most commercially important crops are dispersed via the air as part of their reproductive cycle. The practice of air sampling and spore trapping has long existed for variety reasons, including epidemiology, indoor environmental health, pollen indices and agricultural disease risk assessments. Simply put, spore trapping is the practice of sampling the air for the presence of spores. In the agricultural setting, spore trapping can help farmers in several ways.

Spore trapping assists in making fungicide decisions by providing valuable information about the presence and activity of fungal pathogens in the air. Fungi release spores into the air as a means of reproduction, and the concentration of these spores can indicate the level of disease pressure in a particular area. By using spore trapping devices, growers can monitor the concentration and type of spores present in the air, which can help them make informed decisions about when and what fungicides to apply to their crops. For example, if spore trapping indicates a high concentration of spores for a particular fungal pathogen, farmers can take action to prevent or control the spread of the disease by applying fungicides at the appropriate time.

Fungicides can either prevent or stop the early growth of pathogens in plant tissues. Preventative fungicides act as a protective barrier, while curative fungicides are most effective in the first 24-72 hours after infection. It’s important to apply fungicides before infection occurs to achieve maximum effectiveness. Therefore, early detection of disease is critical. Research from Michigan State University on cucurbit downy mildew showed that spore trapping detected Pseudoperonospora cubensis spores 5-10 days before symptoms appeared. Spornado’s own research shows detection of late blight of Potato and Tomato (Phythopthora infestans) up to 14 days before symptoms appeared.  This early alert of disease in the air enables optimal spray timing, rather than then traditional practice of scouting for signs of disease or using weather based predicative models.

Some research shows that farmers could reduce the number of sprays in a season depending on geography and crop type. For example, research in 2019 in vineyards showed that fungicide sprays were reduced by 25% when using spore trapping to monitor Powdery Mildew.  When comparing predictive weather models to ground truth spore data, we found that the models were too conservative leading to 4 weeks of additional spraying for late blight at the beginning of the potential disease window. Other research (Mahaffee, 2014) shows that on average, grape growers can save about 2.3 sprays / season using spore trapping. 

Spore trapping can save labour when it comes to scouting by reducing the amount physically scouting that needs to occur. By using spore data, agronomists can focus their efforts to scout for the highest risk diseases in the highest affected areas of the field. In vineyards, the visual inspection of 1,000 leaves / acre is required to detect powdery mildew at an incidence of 1% (Mahaffee, 2014). Visual signs of disease are also a lagging indicator of infection; once you see disease it could be too late for fungicides to work optimally. While scouting remains critical to disease management decisions, spore trapping can improve the practice immensely.

Additionally, spore trapping can help growers evaluate the effectiveness of their fungicide programs by monitoring the spore concentration before and after treatment. This can help them determine if their current fungicide program is working, or if adjustments need to be made to prevent further disease spread.

In the greenhouse setting the case for spore trapping is even more evident. High intensity, small grow areas with high value speciality crops really benefit from a preventative approach. Instead of the inefficiency and expense of calendar spraying, an IPM approach can save money on sprays and increase the quality and quantity of the crop yield.

There are many reasons why spore trapping is beneficial to farmers, ultimately allowing better decisions and time savings while improving the bottom line and increasing crop yield and quality. Contact Spornado today to learn more about how spore sampling can help your operation.

Fungicides are an essential tool in agriculture, but their use can have negative impacts on the environment and even the crops they are designed to help. One environmental risk of fungicide use is the impact on soil health, particularly on beneficial fungi.

Fungi play a crucial role in soil health by breaking down organic matter, cycling nutrients, and forming relationships with plant roots that can enhance plant growth and disease resistance. However, fungicides can disrupt these important relationships by killing beneficial fungi along with harmful ones. This can lead to a decline in soil health, reduced plant growth, and increased susceptibility to diseases.

Recent research has highlighted the negative impacts of fungicides on beneficial fungi. A study published in Nature Ecology & Evolution showed how fungicides can lead to significantly lower phosphorus uptake by plants by affecting Arbuscular mycorrhizal fungi. Mycorrhizal fungi have an important symbiotic role with around 80% of plants. They are considered a natural biofertilizer because of their potential to improve soil quality, water stress tolerance and increase nitrogen and phosphorus and pathogen protection in exchange for photosynthesis products from the plant.

In addition to their impact on beneficial fungi, fungicides can also have other negative impacts on soil health. Fungicides can accumulate in soil over time, leading to contamination of nearby waterways and potential harm to non-target organisms such as earthworms, microbes, and other beneficial soil organisms. Fungicides can also disrupt soil microbial communities, which can lead to a decrease in the overall health and productivity of the soil.

Reducing fungicide use is an important part of regenerative agriculture, which focuses on building healthy soils and ecosystems. There are many approaches to reducing fungicide use, including the use of integrated pest management (IPM) strategies, which rely on a combination of different control methods and minimize the use of pesticides. IPM approaches can also include the use of beneficial fungi and bacteria, which can help control fungal diseases without the use of chemicals.

While fungicides remain one of the most important tools for controlling pathogenic fungi and crop diseases, the environmental risks of fungicide are not insignificant, particularly in their impact on beneficial fungi and soil health. Regenerative agriculture approaches that promote soil health and resilience, as well as the use of IPM strategies, can help reduce the reliance on fungicides and promote more sustainable agricultural practices.

“Why did the potato go on a date with the tomato? Because it wanted to ‘ketchup’!”

Potato and tomato are not only a great pairing to eat, but they are also two of the crops that Spornado is highly focused on. Potato diseases can have a significant effect on yields and costs associated with potato production. In Canada, common potato diseases include late blight, early blight, Grey Mold, and silver scurf.

Late blight is caused by the fungus Phytophthora infestans and is the most serious potato disease. The disease can cause extensive damage to leaves, stems, and tubers. Late blight can result in significant reductions in yields (up to 100% if untreated) and the costs to prevent it are high.

Early blight is caused by the fungus Alternaria solani and is also a serious potato disease. The disease can cause extensive damage to leaves and stems. Early blight can cause yield losses ranging from 10 to 30%, depending on the severity of the infection.

Grey Mold is caused by the fungus Botrytis cinerea. The gray mold pathogen overwinters on crop debris, and pathogen spores are disseminated by wind, rain splash and irrigation. Infection requires high humidity and cool temperatures, which start to occur more frequently as rows start to close.  The economic impact of this disease is generally low, but it can mask other diseases and make accurate disease diagnosis difficult.

Silver scurf is caused by the fungus Helminthosporium solani and causes blemishes on tubers that greatly affect white and red skin table potatoes. While generally minor in the field, the disease can spread during storage and can reduce the market value of potatoes.

Tomatoes suffer from some of the same diseases that potatoes do because they are closely related species. In addition to Late blight, Early blight, and Grey Mold which also affect tomatoes, other diseases like Powdery Mildew, White Mold and Septoria leaf spot are usually more common. Each of these diseases can significantly reduce yields and affect crop quality.

Powdery mildew on tomato can be caused by two different pathogens: Pseudoidium neolycopersici and Leveillula taurica. Powdery mildew favours warm, humid conditions and fields under water stress and is much more common in tunnel production and greenhouses versus field grown.

White Mold caused by Sclerotinia affects many crop species and tomato is no exception. Generally attacking around the flowering period, it often invades through dead or injured tissue, or spent flower blossoms.

As its name suggests, Septoria leaf spot, caused by Septoria lycopersici creates a circular spot with yellow halo. The disease starts on lower leaves and spreads to younger leaves. Recommendations for management of this disease is a preventive spray program that requires weekly or biweekly applications. Losses can 100% in heavily defoliated fields.

Whether its Potato or Tomato, early or late blight, Spornado’s disease detection gives you the knowledge to make the best decisions possible. Early detection, better prevention.

Fungicides are a valuable tool in the fight against fungal diseases, however, their extensive use has led to the development of fungicide-resistant strains of fungi. This means that the fungicides that once worked effectively against these fungi are now ineffective. This is becoming a large concern in the world of agriculture as some common fungicides that farmers have relied on for years are losing their effectiveness. In fact, diseases of the crops we all know and love like grapes, apples and strawberries are showing resistance. Powdery mildew of grape, apple scab and strawberry anthracnose diseases are known to be becoming resistant to FRAC 11 fungicides and can cause considerable crop losses for growers.

A project funded by the Ontario Agri-Food Research Initiative allowed us to combine fungicide resistance testing with the Spornado early alert system for crop disease, which detects disease before it can be scouted. Over two seasons we tested Spornado’s ability to detect Powdery mildew, Downy mildew and Anthracnose and the G143A mutation that causes FRAC 11 QoI resistance. This new test allows the Spornado to assist in the selection of fungicides that may be more effective if resistance is detected.

This project collected samples from five vineyards in the Niagara region, three apple orchards and three strawberry fields both from the Southwestern Ontario. Disposable sample cassettes from the Spornado air sampler were changed twice a week.  The cassettes were then couriered overnight to Sporometrics testing laboratory. Samples were first tested for presence of the disease, if positive, further tested for the presence of the resistance mutation.  The results are shown in the table below:

Year                       Samples               QoI Resistant     QoI Sensitive

2021                       67                           59                           8

2022                       191                         171                         20

This data shows QoI resistance is widespread in the some of the most common diseases of Grape, Apple and Strawberry in Southern Ontario. When fungicides no longer work as they should, farmers and growers lose yield and quality. Additionally, fungicide-resistant strains of fungi can spread to other farms and fields, making it even harder to control the diseases they cause.

Fungicide resistance is a complex issue, and there is no one-size-fits-all solution. However, there are steps that farmers and growers can take to slow the development of fungicide resistance, such as rotating the types of fungicides they use, using them at the proper rates and timing, using disease-resistant varieties and other IPM practice, and monitoring for the development of resistance.