Field Observations

July 9, 2026

Winter wheat harvest has just begun in the deep southwest. Corn and soybeans continue to grow, and timely rains and moderate warmth will help these crops succeed.

Corn

Early-planted corn is nearing the end of the vegetative stage, and the number of potential kernels is being finalized. Under severe stress, kernel numbers will be reduced. Tassel emergence in earlier-planted fields will begin within the next couple of weeks. When the last branch of the tassel emerges from the whorl, the VT stage has been reached (VT stands for vegetative tassel stage). To get a rough idea of the anticipated time frame for tassel emergence, pull the whorl out of the plant and unfurl the leaves. The number of leaves wrapped around the tassel, multiplied by a factor of two, three, or four (two to four days per leaf emergence, depending on growing conditions), will give a rough estimate of the number of days until tassel.

Heavy rains and wind moved through Ontario again over the past week. Unfortunately, in some cases, the combination of very strong wind and torrential rain lodged corn. Some corn has rebounded with help from its brace roots, while other corn may have a goosenecked appearance as it continues to grow.

Field Crop News shares that rain makes grain. Learn more about how rainfall from mid-June to mid-July influences corn yields, with research financially supported by Grain Farmers of Ontario.

Tar spot has yet to be confirmed in the province this year; however, that can change quickly and should be monitored, as conditions have been optimal for infection in some areas. Areas with a history of high infection, such as along the shores of Lake Erie, will most likely see some incidence of the disease identified within a few days. Anticipated tar spot infections will occur in fields with a history of tar spot and in those with a larger canopy, such as earlier-planted corn, because larger canopies create ideal conditions for disease development. Late-planted corn that has not canopied yet, or corn planted in wide rows, would not be a concern until the crop reaches the V8 to VT stages and the canopy is large enough to be conducive to infection. These late fields may miss the early calendar date but may still be affected as the disease develops this summer. Scouting fields is the only sure way to confirm infection, but apps such as Crop Risk Tool can help identify risk levels based on weather forecasts. Tar spot is now endemic in western Ontario, where there have been several years of infection and the disease overwinters in soils. Infection will start lower in the canopy if it is caused by spores within the field.

Indiana is so far reporting tar spot infections. This can lead to future infections in Ontario fields as spores are released and wind patterns move them into unaffected areas. Airborne spores will infect the top of the canopy.

Scouting and identifying the location of the disease in the canopy helps indicate whether the field was self-infected or the infection was airborne. Either way, the disease is present, and the earlier the crop can be treated, the more leaf tissue and plant health can be preserved to maintain yield potential. Timing is important, as most fungicides are effective for only about 14 days. The sooner the crop is sprayed, and the earlier the growth stage, the more likely a second spray will be needed if conditions are favourable for disease development. Select fungicides that control tar spot, as not all fungicide products do. If spraying when silks are still green, consider the risk of gibberella ear rot, as it produces DON mycotoxin. A tank mix with a product that also controls gibberella ear rot should be considered if spray timing is at the green silk stage (R1).

Soybeans

Soybean stages range from vegetative growth to R2 (full bloom). At R2, plants have an open flower at one of the two uppermost nodes on the main stem. From R2 to R4, soybeans rapidly take up water and nutrients, with uptake peaking at R4. It is important to keep soybeans healthy for optimum yield.

Watch for diseases such as white mould and insects such as aphids. See last week’s field observations for more information.

The Ontario Crop Protection Hub is a helpful reference for herbicides, fungicides, and insecticides registered in Ontario. Always wear personal protective equipment and follow the label.

Double-crop soybeans may be planted after winter wheat when possible. More information on double-cropping soybeans, and factors to consider when double-cropping, can be found in last week’s field observations.

Cereals

Winter wheat harvest has begun at a low rate in the deep southwest, as weather and crop drydown allow. Rainstorms that moved through the area have caused some delays in getting into fields.

As harvest progresses and moves across the province, keeping an eye out for Fusarium is imperative. Using a visual scale to estimate Fusarium severity across fields can help target which fields to harvest first. The aim is to harvest the fields with the highest severity first, as DON levels can almost double each time a storm rolls through. When harvesting, aim to set the combine to blow out Fusarium-damaged kernels. If moisture is higher, this may be more challenging. Some key tips are included in the link above. Note that lodged wheat has an increased potential for Fusarium infection and DON production. More can be found here.

Another concern on farmers’ minds is the chance of sprouting as scattered rain showers continue.

The winter barley harvest is wrapping up.

Spring cereals are approaching the boot-to-head stages.

Cover Crops

Cover crops can be an important tool in any farming operation to help increase organic matter, reduce soil erosion, suppress weeds, and more. Learn more about a current, innovative Living Lab – Ontario drone seeding cover crop project in this past Ontario Grain Farmer article. Grain Farmers of Ontario is a core partner of Living Lab – Ontario.

For more insights on cover crops, along with the how, the why and their benefits and challenges, as told by farmers, watch this past Grain Farmers of Ontario GrainTALK webinar.

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July 2, 2026

Wild weather, including hail, a tornado, and flooding, was seen over the past week. Winter wheat harvest is creeping closer, and corn and soybeans are being scouted for insects and disease.

Corn

The corn crop is developing nicely as we move into the summer months. Corn is staging between V5 and V11. Around V5, the growing point is above the soil surface. At V9, the tassel is rapidly developing but is not yet visible at the top of the plant. New leaves appear every two to three days, and ear shoots are also developing.

Significant storms rolled across the province late last week, bringing heavy rain, a tornado, and up to golf ball-sized hail. For more information on how to manage a crop that has been impacted by hail, read this past Field Crop News article.

Nitrogen is still being side-dressed and top-dressed across some areas of the province.

Tar spot has been identified this summer in Indiana. If conditions warrant, be prepared to apply a fungicide that controls tar spot when the forecasted risk level is high, favourable weather is present, and the disease has been identified in the local area in previous years.

The Crop Risk Tool  provides weather-based forecasting and risk assessments for various crop diseases, including tar spot, northern corn leaf blight, and Gibberella ear rot, helping farmers make data-driven decisions. The tool allows users to select the crop, location, planting date, and more to create a risk assessment. The optimum time to run the risk assessment is approaching and is between V10 and R3.

It is best to manage tar spot during corn growth stages V8 to R4. Always read and follow labels, and speak to a local agronomist before making a spray decision.

Soybeans

Soybeans are staging anywhere between V1, the first trifoliate, and R1, beginning bloom, when at least one flower appears on the plant on any node on the main stem. Staging is important as the season progresses so herbicides, fungicides, and insecticides can be applied safely and effectively, as required.

Fields are looking a bit stressed in some areas because of saturated soils. In some fields, nodulation is not occurring yet, and soils are denitrified from prolonged ponding. Symptoms of yellow and stunted plants can be seen between tile runs or in lower areas with heavier soils. As the plant reaches the V2 to V3 stage, nitrogen fixation begins; however, saturated soils affect nitrogen fixation because the processes, and the associated bacteria, need gas exchange for activity.

Root and stem rots can also be common in soils that have excess moisture.

Keep an eye out for soybean cyst nematode (SCN) damage as the season progresses. At high populations, nematodes can cause yellowing leaves, stunting, and early maturity, often in circular patterns. SCN can be tested for and should be monitored every three to six years; more information can be found here.

Fungicide timing is occurring or approaching for white mould control. Timing is the key to getting the most benefit from fungicide applications. Risks for white mould include field history. If there is a known history of white mould, the chance of it recurring is high. Variety, row spacing, plant density, and how quickly the field will canopy all factor into the likelihood of infection. Weather patterns will also help determine the risk. When it is foggy or humid, and moisture is on the plant most of the day, there is a higher risk of white mould.

The Crop Risk Tool provides weather-based forecasting and risk assessments for various crop diseases, including white mould and frogeye leaf spot, helping farmers make data-driven decisions. The tool allows users to select the crop, location, planting date, and more to create a risk assessment.

Fungicides can lower the severity of white mould infection; however, timing is critical. The application timing ranges from R1, a single flower on the main stem, to R3, a pod on the main stem. Be sure to speak with your agronomist for optimum timing and product selection, and always follow label recommendations.

Keep an eye out for aphids. When scouting for aphids, the threshold before spraying is that 80 per cent of the plants in the field have at least 250 aphids per plant, with an increasing population. Scouting should occur multiple times over a period before an insecticide application is warranted to ensure the population is increasing. The Aphid Advisor app is a great resource to help make decisions.

A reminder as the season progresses: Grain Farmers of Ontario, through research funding, has supported the development, with OMAFA, of the Pest Manager app, which allows you to identify, map, and find integrated management options for common weeds, insects, and diseases in corn, soybeans, and cereal crops. The pesticide use information in the app is specific to Ontario, and users should always read the product label before use.

Cereals

Spring cereals are in the heading stages. It takes roughly 660 growing degree days to fill a wheat head. This period spans approximately 25 to 30 days for grain fill, or less if it is extremely warm, which is not a long time.Winter wheat is staging from soft dough, GS85, to ripening, GS87. During the dough stage, the green colour of the kernel, glume, and peduncle begins to fade. With the hot weather experienced this week, wheat plants will mature quickly.

The maturity of wheat can be determined by the peduncle changing from green to yellow. At this point, the crop is fully mature; grain fill and the translocation of plant sugars have been completed. This stage can be compared to the black layer on corn.

Winter wheat harvest will begin, as weather and crop stage allow, in the next couple of weeks in the deep southwest region of the province. As harvest begins, scout for fusarium-damaged heads in the field. Infected fields should be harvested first to limit continued toxin build-up in case of rain events or delayed harvest. Set the combine correctly to help blow out the lighter, infected kernels. Fusarium is showing up at low levels, sometimes only infecting a few florets on a few plants within a field. This might be due to T3 fungicides being applied at ideal timing for the majority of the field, while some tillers might have pollinated slightly behind the rest of the field.

The incidence of fusarium infections has been reduced over the past 20 years due to genetic improvements and the use of fungicides during pollination, T3 timing, to help control fusarium. This spring, a larger amount of the winter wheat crop was exposed to ideal conditions — think of the disease triangle for fusarium infection: susceptible host + pathogen + favourable environment — but farmer practices have helped manage the incidence of infection.

If winter wheat is harvested and yield and quality reductions due to high fusarium levels are experienced, be sure to contact Agricorp.

With the moisture seen last week and lodged wheat, sprouting could also be a concern, especially if the weather turns wet again. Keep an eye out for sprouts and harvest early. Review any delivery contracts and look for the grain specifications required for delivery. Ship grain that meets the required specifications that are signed off on. The most notorious inclusion on contracts is the base falling number requirement, which can be caused by rainy weather and sprouting or by high alpha amylase expression in the grain due to cold stress during grain fill.

With an early wheat harvest, double-crop soybeans are a common conversation in some areas. If aiming for double-crop soybeans, seed supply on early-season beans will be needed. The date of wheat harvest and the field location will determine a lot. Aim for seed maturity that is at least one full maturity group shorter but check with your seed dealer about what they suggest and what is available.

The seeding rate should be increased to at least 250,000 seeds per acre. The planting date should be considered, looking at frost dates, as the yield potential will drop considerably if soybeans are planted too late. Early to mid-July planting dates are ideal; be sure the soybeans are going into good conditions. The ideal planting dates for double-crop soybeans would be before July 10 in southwestern Ontario and before July 20 in the deep southwest, but there is a large risk at any date; the soybeans might yield or they might not.

Managing straw is critical, so be sure to spread straw and chaff evenly. If you are considering baling, realize that the time spent baling might keep you out of the field planting for a couple of days. If you plan to double-crop soybeans, plant to moisture, up to three inches in July, as they will push through. If there is no moisture at that level, aim for a one-inch planting depth and hope for rain.

The need for weed control in double-crop soybeans will be lower. In theory, one pass would still be needed to control weeds. Most annual weeds emerge during May and June, and if double-crop soybeans are planted in July, weed pressure should be considerably lower. Limit the investment in weed control, as the chance of good soybeans is less likely, with much relying on the weather co-operating for a good yield and harvest so late in the season.

4R and soil sampling

As winter wheat is harvested, it is a great time to complete soil samples to ensure the right rate of fertilizer is being applied at the right time, in the right form, and in the right place, following the 4R principles.

Cover crops

Cover crops have an important role in maintaining soil productivity and quality. After cereal crops are harvested, it can be an ideal time to plant cover crops. The Cover Crop Selector Tool uses Ontario-based research, supported by Grain Farmers of Ontario, to help farmers select the best cover crops and provide management support, including planting population, for their operation.

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June 25, 2026

Timely rains have allowed grain crops across the province to flourish as the month comes to a close. With corn, soybeans, and spring cereals growing vegetatively, and winter wheat in the grain-fill stages, it is still important to actively scout fields for insects, disease, and weeds.

Corn

Rain and moderate temperatures over the past week have helped corn progress quickly. There is still a high degree of variability in crop staging across the province, from V1 to V9.

At about the V6 stage (six collars, or eight-leaf stage), the growing point emerges above ground level. The critical stage of ear development runs from this stage to about a week before pollination. Ear initiation begins, and kernel rows per ear are then determined. The number of kernels per row is determined as the ear elongates, before pollination. Stress in the coming weeks from a lack of nutrients or moisture will reduce grain potential through reduced kernel numbers. Stress can be caused by many factors, including populations that are too high, weed pressure, root pruning from machines or insects, lack of fertility, lack of rainfall, standing water, hail damage, and disease.

Rapid growth syndrome has been seen, and can continue to appear in fields experiencing shifts from cool conditions to high heat. The syndrome occurs when corn leaves do not unfurl properly, and the whorl becomes tightly wrapped and twisted.

Be aware of crop stage as resprays occur and consider that some plants may be more advanced than much of the field, which could increase the risk of herbicide injury.

Side-dressing and top-dressing are occurring. With recent heavy rains, there have been questions about nitrogen losses. Several factors can affect losses, and there is no firm answer on total loss potential.

• The greatest chance of nitrogen loss is in areas where water has been sitting in fields. The longer water has sat in a field, creating saturated conditions, the higher the chance of loss through denitrification.
• Cooler temperatures also come into play. Typically, there is less loss under cool conditions.
• If all nitrogen was applied pre-plant, losses will likely be higher than if some was side-dressed in the past couple of weeks. Overall, the consensus is that urea and UAN take one to three weeks to convert to nitrate, so the longer they have been applied, the higher the chance of loss.
• PSNT testing can help determine the level of nitrogen in the soil.

As fungicide timing approaches, be aware of the potential for tar spot and Gibberella ear rot, which can cause DON in corn. Scout fields for disease, as the plant is vulnerable to tar spot between V10 and R3 (milk stage). The Ontario Corn Committee shared the 2025 Ontario Corn Hybrid DON Screening Trials last fall. These trials may be helpful in determining how susceptible hybrids are to Gibberella ear rot and DON accumulation. Use them as a tool as fungicide spraying approaches. Tar spot has been identified in Indiana so far this year.

Soybeans

Soybean fields are staging from VE (emergence) up to beginning bloom (R1, when plants have at least one flower at any node). Soybean planting has mostly wrapped up in areas that struggled to plant earlier this year, and some replants are also occurring. Heavy rains last week caused ponding in some fields.

In the V3 to V5 stages, axillary buds develop into flower clusters near the top of the stem. In the coming days, flowering will begin, starting on the third to sixth nodes and continuing down the stem. At this point, the plant will transition into reproductive stages (R1) while continuing to grow vegetatively.

As resprays occur, be sure to mitigate drift. Both BeDriftAware.ca and a past Grain Farmers of Ontario GrainTalk webinar with Dr. Jason Deveau have valuable tips for spraying to help mitigate drift.

Agricorp planting deadlines and reporting of final acres for soybeans are due June 30.

Cereals

Spring cereals are in the stem elongation to boot stage.

Winter wheat harvest will begin gearing up in the next couple of weeks in the deep southwest. As harvest approaches, scout for fusarium-damaged heads in the field. Infected fields should be harvested first to limit continued toxin buildup in case of rain events or delayed harvest. Set the combine correctly to help blow out the lighter infected kernels. Fusarium can show up even at very low levels after a T3 application, sometimes only infecting a few florets on a few plants within a field. This might be due to T3 fungicides being applied at the ideal timing for most of the field, while some tillers may have pollinated at a slightly different time. The incidence of fusarium infections has been reduced over the past 20 years due to genetic improvements and the use of fungicides during pollination (T3 timing) to help control fusarium. This spring, some regions of the province saw ideal conditions for fusarium development, while others did not. Think of the disease triangle for fusarium infection: susceptible host, pathogen, and favourable environment. Farmer practices have helped reduce the chance of infection.

Across much of the province, kernel fill is still occurring in the winter wheat crop (GS 73 early milk to GS 83 early dough). Over the past few weeks, grain-fill weather has been nearly ideal, with moderate temperatures and timely rains. Prolonged hot, dry weather would limit kernel fill, resulting in smaller kernels as water availability for the crop becomes limited, and the plant progresses rapidly through growth stages. Kernel abortion and dead heads could also be seen as the plant dies rather than matures if moisture becomes too limited during this period, often seen on sandy knolls within fields in past years.

Heavy rains affected parts of the province over the past week, causing lodged wheat in some cases. These fields should be prioritized for harvest, as lodged wheat can often create ideal conditions for disease.

Cereal leaf beetles, cereal aphids, and true armyworm have all been identified in Ontario fields, with some populations meeting thresholds. Scout for these pests, monitor, and control as needed. Keep pre-harvest intervals in mind, as wheat harvest is quickly approaching for some. More information on these pests can be found in past Field Observations.