Field Observations
SUMMER 2026
July 30, 2026
Winter wheat harvest continues across the province between rains. The corn crop is pollinating and in early reproductive stages, while the soybean crop is in the mid-reproductive stages across much of the province.
Corn
Corn is currently staging from the late vegetative stage (V12) to the kernel blister stage (R2), with the majority of the crop at VT to R1. The R2 growth stage is reached 10 to 12 days after silking, as kernels develop white “blisters” that contain clear fluid. Pollination is one of the most critical times in the lifecycle of a corn plant for yield.
During pollination, the silk emerges from the corn husk, while the tassel emerges at the top of the plant. The first silks to emerge from the ear are from the lower end of the cob. Once silks have emerged from the corn husk, they may elongate by one to two inches a day, slowing over time and stopping growth once a pollen grain encounters the silk. Some fields may have silks emerging before tassel emergence and may see very long silks. When silks emerge before the tassel, they may not be as receptive to pollen by the time pollen is shed and present. This can result in fewer kernels and/or missing kernels, especially at the base of the ear. Corn hybrids have often been designed to help combat drought stress by promoting active silk emergence and reducing the chances of delayed silk emergence. However, when growing conditions are ideal, silk emergence can sometimes occur before tassel emergence.
A common issue that can also be seen in fields experiencing drought conditions is delayed silking, which can cause missing tip kernels. Corn silks are made up of a lot of water, and drought can reduce silk growth and emergence. The two weeks before pollination and the two weeks after can often be the most sensitive period for moisture stress in the corn crop.
Heat stress can also affect corn pollination. Excessive heat can cause silks to die sporadically, creating poor pollination and erratic kernel set on the ear, especially in more severely stressed areas of the field.
After pollination, it is a good time to do a pollination check by performing a shake test. To do a shake test, husk back the ear after pollination and shake it with the tip of the cob toward the ground, allowing silks to fall off the cob. Silks remaining attached will be fresh, green, live silks that have not been pollinated. Kernels will not form if there is no more pollen or if live silks are not outside the husk.
Keep an eye out for tar spot in fields. Look in the upper canopy for infection that has been blown in on storm systems. Look in the lower canopy to find infection that has self-infected from previous crop residue. Look for black, slightly raised spots on the leaves that do not wipe off. Learn more about tar spot.
With later-planted corn pollinating later in the season, there may be a higher risk of Gibberella ear rot infection and potential DON accumulation due to the environment during pollination. Speak with your agronomist and create a plan for fungicide applications if warranted. More on this topic was included in last week’s e-news article.
For the past several years, Bt corn has provided protection against European corn borer. However, that protection is being threatened as populations resistant to Bt genes spread in Canada. Learn more about this pest and the threat in the infographic below.
Soybeans
Soybeans are currently in the vegetative stage in late-planted fields and staging up to R3, or beginning pod, in others. Many soybeans are close to a critical stage and need moisture to help determine productive yield. During the R2 to R4 period, there are large demands for moisture. For much of the province this year, moisture has not been too much of a concern. However, some areas have seen a lack of moisture over the past three weeks or so, and soil-available moisture can change in other areas if drought periods arise over the next few weeks. The R4 to R6 growth stages are when the plant starts to accumulate dry matter in the pods and seeds. Stress during this time can cause major yield reductions, more than any other period of soybean growth.
It is a tale of two conditions when it comes to moisture. Some areas have had ample moisture over the past week, while others have had limited moisture. In areas with ponding water, symptoms of root rots (Rhizoctonia, Fusarium, and Phytophthora) may be observed due to wet, saturated ground.
A disease to keep an eye out for is red crown rot. This soil-borne fungal disease has not yet been confirmed in the province but has been identified in several nearby states. It can affect yield quite drastically. Learn more about this disease in the Grain Farmers of Ontario Agronomy Factsheet.
Cereals
Field Progress, Grain Farmers of Ontario’s weekly estimate of planting and harvest progress across the province by district, reports that winter wheat harvest was at 63 per cent as of Wednesday, July 29, 2026. Many are reporting average to above-average yields, with good quality. Good yields have also resulted in good straw yields.
Many remove straw from the field to use for animal bedding. However, straw has significant benefits when left on the field, including increasing organic matter, increasing residue to reduce soil erosion, and providing a valuable source of nutrients that can be broken down and remain in the field.
The table below provides an overview of phosphorus and potassium levels removed from one ton of straw and the corresponding estimated fertilizer costs to replace those nutrients.
| Nutrient | Avg. to Max. Removal (lbs actual/ton) | Fertilizer | Fertilizer Replacement (lb/ac) | Fertilizer Cost ($/lb) | Value ($/ac) |
| Phosphorus | 3.2 – 6.0 | MAP (11-52-0) | 6.5 – 11.5 | 0.60 | $3.90 – 6.90 |
| Potassium | 16.8 – 42.5 | Potash (0-0-60) | 28 – 70.8 | 0.50 | $14.00 – 35.40 |
| Total value ($/acre): | $17.90 – 42.30 | ||||
| Total value (¢/lb of straw): | ¢ 0.8 – 1.92 |
*A MAP value of $1,320/metric tonne and a potash value of $1,080/metric tonne were used in these calculations.
Source: https://fieldcropnews.com/2022/07/ontario-field-crop-report-july-27-2022/
Spring cereals are in the final stages of grain fill and the beginning stages of ripening and will be harvested in the next several weeks.
Soil sampling and cover crops
After winter wheat harvest is an ideal time to complete soil sampling to get a better understanding of soil nutrient levels for upcoming nutrient applications. According to the 4Rs — right rate, in the right place, at the right time, and from the right source — soil sampling should occur every four years. Making fertilizer recommendations without a soil sample or using a sample that is older than four years does not meet 4R requirements.
Cover crops after winter wheat are a great choice to increase soil health, keep nutrients from leaching, and increase soil organic matter. The Cover Crop Tool uses Ontario-based research, much of it funded by Grain Farmers of Ontario, to help find the best cover crop to meet each operation’s goals.
Weeds
Curious about what resistant weeds are being found across the province this year? View the 2026 mid-season weed survey results for a summary of weed species that have been sent in for identification and herbicide resistance testing. Grain Farmers of Ontario helps fund this weed resistance testing.
If there are suspicious weeds in fields, learn more about weed resistance testing and view a database of resistant weeds here.
July 23, 2026
Winter wheat harvest continues across much of the province. As corn and soybeans move into the reproductive stages, diseases such as tar spot are being scouted for, while insects such as western bean cutworm and corn rootworm are also on the radar in corn. In soybeans, white mould, aphids, and more are being scouted for.
Corn
Corn development is still variable across the province, with fields ranging from vegetative stages to R1 (silk — one or more silks extend outside the husk leaves) in the earliest-planted crop.
Around this time of the season, western bean cutworm (WBC) eggs are often observed in corn fields, with some WBC larvae hatching and on the move. Tracey Baute, OMAFA, shared the following with Grain Farmers of Ontario:
Western bean cutworm activity has increased over the last week. Moth counts are increasing, and egg masses and larvae are likely present in early-planted fields that are already in tassel or early silk stages. Earliest-planted fields should be scouted first, followed by later-planted fields that will just be entering the early tasselling to green silk stages when peak flight occurs. More information on western bean cutworm scouting and thresholds can be found on CropIPM.
Corn rootworm (CRW) monitoring is occurring in fields. Watch this past GrainTALK webinar on Management strategies and innovative research on corn rootworm to learn more about the lifecycle of the pest, best management practices, and more. The Canadian Corn Pest Coalition provides a chart of the Bt corn products available, and what each trade name and insecticidal protein provides protection for. However, it is important to note that CRW resistance can occur, with resistance potential especially high in continuous corn production. Rotation is key. More on this pest can be found here.
Corn fungicide timing is at hand, depending on the protection goal and product used. Many different ear disease infections can occur at silking, as the silks are a key entry point into the ear for pathogens such as Gibberella (Fusarium graminearum). Depending on weather conditions and the spores in each field, ear disease development begins at pollination. Infections can also occur due to ear damage from insects, animals, or hail. Which ear disease takes hold will depend on what spores are in the field, and what weather conditions are ideal for those spores during and after infection. It is all about timing.
Gibberella ear rot is always a topic as the corn crop is pollinating. Infection occurs with warm temperatures (27 C) and humid conditions, combined with rainfall that splashes fungal spores onto the silks two to six days after emergence. Cooler, wet weather after silking also favours disease development. Extended periods of rain in the fall promote fungal growth and increase disease severity. More on this infection can be found here. Check the susceptibility of each hybrid and manage accordingly for Gibberella ear rot and DON. GoCrops.ca shares the 2025 Ontario Corn Hybrid Screening Trials Report; this report gives an indication of corn hybrids’ susceptibility to DON infection. The Ontario Crop Protection Hub is a great reference for herbicides, fungicides, and insecticides registered in Ontario. Always wear PPE and follow the label. Spraying at silking, when silks have fully emerged, are green, and are not dried up, is recommended to best manage Gibberella, as silk channel infection can occur two to six days after silking, with symptoms appearing two to three weeks after infection. Be sure to scout fields, as this year, some tassel emergence is delayed while silk is present. Don’t just rely on the drive-by scouting method, which might not show the true staging story.
Be sure to scout for tar spot. It was found and confirmed in Michigan earlier this month. Tar spot was discovered in Ontario in 2020, and moved as far east as the Peterborough and Northumberland regions in 2024. Ideal conditions for development are when plants have more than seven hours of leaf wetness. With recent weather patterns, fields that had the disease last year are at higher risk. Scouting fields is the only sure way to confirm disease infection, and the Crop Risk Tool can aid in identifying risk levels based on weather forecasts. Read the Grain Farmers of Ontario fact sheet to learn more about this disease. The Ontario Crop Protection Hub indicates fungicides that have activity to help control tar spot. Timing of application is important if spraying when the silks are still green. Also, consider the risk of Gibberella ear rot, as it will produce the DON mycotoxin. If spray timing is at the green silk stage, a tank mix with a product that also controls Gibberella ear rot should be considered (R1). For more information on tar spot, view the past GrainTALK webinar with Albert Tenuta and this Crop Protection Network webinar.
Keep an eye out for northern corn leaf blight. The incidence of this disease has increased in past years due to several factors, including:
- more corn-on-corn production;
- more corn residue, due to an increase in no-till or reduced tillage;
- intensive corn management strategies;
- favourable environmental conditions; and
- the development of new northern corn leaf blight races that resistance genes are not controlling.
This past Field Crop News article has more information on northern corn leaf blight.
Common rust can also begin showing up in corn fields around this time of year. Ideal conditions for its arrival are high humidity, nighttime temperatures of 18 C to 21 C, and moderate daytime temperatures. It is rarely a major concern, but it is good to be aware of what might be showing up in fields.
Soybeans
Soybeans are anywhere from V4 in late-planted fields to R4, or full pod, when pods are three-quarters of an inch long at one of the four uppermost nodes on the main stem. Overall, fields are looking variable.
Fungicide timing is occurring or approaching for white mould control, especially in high-risk areas. The key to getting the most benefit from fungicide applications is timing. Risks for white mould include field history. If there is a known history of white mould, the chance of it recurring is higher. 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 risk. When it is foggy or humid, and moisture is on the plant most of the day, there will be a higher risk of white mould. The Crop Risk Tool can help determine a field’s risk level. Fungicides can lower the severity of infection; however, timing is critical. Application timing ranges from R1 (single flower on the main stem) to R3 (pod on the main stem). Be sure to speak with your agronomist for optimum timing and product selection, and always follow label recommendations. Learn more about this disease in the Grain Farmers of Ontario white mould fact sheet.
With recent conditions, keep an eye out for aphids. Pockets of this pest often show up in regions of the province each year. When scouting for aphids, a threshold that should be reached before spraying is 80 per cent of the plants in the field having 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.
Tracey Baute, OMAFA, also shares that “two-spotted spider mite (TSSM) infestations are showing up in a few soybean fields. More sightings are expected in the next week or two, given that wheat harvest is underway and hot temperatures continue. Over the last three years, more than half of the soybean fields tested have had dimethoate-resistant TSSM populations. Sampling has also determined new species of spider mites not previously known to be in soybeans or beans. This year, we are looking for more samples to document the mite species and test for resistance at Western University as part of a Grain Farmers of Ontario-funded project. Anyone finding populations before or after a dimethoate application in soybeans or dry beans should contact Tracey Baute to collect samples for testing.”
Cereals
As some areas are winding down from winter wheat harvest, others are just getting started, with most of the province working on the 2026 winter wheat harvest. So far, yields have been average to variable, depending on rainfall amounts in the field and temperatures through the grain-fill period. Field Progress, Grain Farmers of Ontario’s weekly estimation of planting and harvest across the province by district, reports that winter wheat harvest is at 44 per cent as of Wednesday, July 22, 2026.
Glume blotch on wheat has been identified in fields. It is a fungal disease that causes brown or purple blotches on the glumes, which bracket the wheat grain, or small yellow flecks or spots on the leaves that become yellow halos and turn brown to greyish brown. It can impact the plant from seeding to maturity, reducing test weight when the seed is affected. Glume blotch often occurs when wet, humid conditions persist.
Spring grains are in the grain fill stages.
Weeds
Have there been some tough-to-control weeds this year? Tough-to-control weeds might be partly due to weed size when the sprayer finally got into the field because of wet conditions, or poor crop stands allowing late-season weed emergence. However, some might be due to resistance.
Be sure to scout for waterhemp, which is resistant to multiple herbicide groups in various regions of the province. Also watch for Palmer amaranth, a new weed identified last year that is highly competitive, can spread easily, and has known resistance to nine different herbicide groups. If you think there might be a Palmer amaranth plant in a field, contact Mike Cowbrough, OMAFA.
Soil Fertility Webinar Series
Watch Grain Farmers of Ontario’s three-part GrainTALK webinar series focusing on soil fertility. While each webinar stands on its own, the series is designed to tell a complete story — from soil sampling to building a fertilization plan.
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 the 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, their benefits, and their challenges, as told by farmers, watch this past Grain Farmers of Ontario GrainTALK webinar.
July 16, 2026
Wheat harvest is off to a strong start this week, with farmers from Windsor to London beginning harvest, and some areas already finished. The rest of the province will begin harvesting soon as wheat matures. Corn and soybeans are developing quickly in the summer heat, and stress areas in fields — including water damage and compaction — are becoming more visible as plant water demand peaks and root damage limits uptake. Smoky skies have kept temperatures down a few degrees, but they have also made outdoor work harmful to human health.
Corn
Corn across the province is ranging from V10 in late-planted fields to early VT, as tassels begin to emerge in early-planted corn. As corn nears the end of the vegetative stage, it is finalizing the number of potential kernels. Under severe stress, kernel numbers will be reduced. Lack of moisture at pollination can reduce silk development and shorten the pollination period, resulting in fewer kernels being pollinated and fewer kernels per cob. So far this year, there have been few moisture-limiting concerns; if anything, there has been excessive moisture. However, this can change quickly. Saturated soils have kept roots shallow. Shallow roots caused by wet or compacted soil will show drought stress quickly when conditions turn hot and dry, as roots cannot grow fast enough to reach water as they might have after a drier spring.
Gibberella ear rot infections occur with warm (27 C), humid temperatures and rainfall that splashes fungal spores onto corn silks two to six days after silk emergence. With recent conditions, Gibberella ear rot could be a concern. Check the susceptibility of each hybrid and manage accordingly for Gibberella ear rot and DON in corn. GoCrops.ca shares the 2025 Ontario Corn Hybrid Screening Trials Report; this report gives an indication of the susceptibility of corn hybrids to DON infection. The Ontario Crop Protection Hub is a useful reference for herbicides, fungicides, and insecticides registered in Ontario. Always wear personal protective equipment and follow the label. Spraying at silking, when silks have fully emerged and are not dried up, is recommended to best manage Gibberella, as silk channel infection can occur two to six days after silking, with symptoms appearing two to three weeks after infection.
Be sure to scout for tar spot. Tar spot was discovered in the province in 2020 and had moved as far east as Peterborough and Northumberland counties by 2024. Ideal conditions for development occur when plants have more than seven hours of leaf wetness. Much of the province has not yet experienced these conditions, as it has been quite warm and dry overall; however, this can change. At this point, earlier-planted fields are at higher risk due to the larger canopy, along with fields that had the disease last year. Scouting fields is the only sure way to confirm disease infection, but the Crop Risk Tool can help identify risk levels based on weather forecasts. The Ontario Crop Protection Hub indicates fungicides that have activity to help control tar spot. Timing of application is important. If spraying when the silks are still green, also consider the risk of Gibberella ear rot, as it can produce the DON mycotoxin. If spray timing is at the green silk stage, a tank mix with a product that also controls Gibberella ear rot should be considered (R1). For more information on tar spot, view the past GrainTalk Webinar with Albert Tenuta and this Crop Protection Network Webinar.
With a wide range of maturities and planting dates, it will be important to know the stage of each field to apply fungicides at the right time for the best control.
Soybeans
Soybean stages range from vegetative growth to R3, or early pod development, when there is a pod at least 3/16 inch long, but less than 3/4 inch long, at one of the four uppermost nodes on the main stem with a fully developed leaf. Soybean plants usually flower over 25 to 35 days, with flowering still occurring as pods develop.
Pay attention to the amount of moisture soybeans are receiving while they are flowering. In some parts of the province, farmers should be on defence against white mould. The ideal timing for fungicide applications is between the R1 and R3 stages, when infection is occurring. Some may choose one pass of fungicide, approximately 15 days after flowering begins, while others may choose two passes: the first when most plants have a single flower, followed by a second eight to 10 days later, so both passes are applied during the peak flowering period. More information on white mould can be found in the Grain Farmers of Ontario factsheet.
For more information on white mould and other diseases to watch for in soybeans, view the past GrainTalk Webinar with Albert Tenuta.
Cereals
Winter wheat harvest was stop-and-go last week in southwestern Ontario. Wheat was mature, but fields needed dry weather. This week’s dry weather has seen harvest in some areas go from zero to 75 per cent within the week. Field Progress, Grain Farmers of Ontario’s weekly estimate of planting and harvest across the province by district, estimated winter wheat harvest at 16 per cent as of Wednesday, July 15, 2026.
Harvest can be limited by overcast skies, heavy dews, and rain showers that prevent plants from drying. When combines are rolling, moisture levels range from 16 to 10 per cent, with reports of decent test weight. Fields lodged during grain fill will show lower test weights; harvest delays and wet conditions can also affect test weight and sprouting.
Heavy rains and strong winds have moved through the province over the past couple of weeks, and some fields have lodged. Lodging certainly makes harvesting more difficult, but it can also lead to disease development. When a plant is lying on the ground, it remains wet longer than if it were standing, increasing disease risk. If a field is mature, aim to harvest lodged fields first to limit disease incidence and poor grading at the elevator.
Black point, which appears as black smudging or discolouration on kernels or as a black cloud of spores around the combine at harvest, could be a slight concern. The disease develops when conditions are wet and warm during the grain fill and ripening period. More can be learned at the 23:24 mark of this Grain Farmers of Ontario GrainTalk Webinar.
Spring cereals are in the midst of grain fill.
Smoke rolled into southern Ontario on Wednesday, darkening the skies and reducing some of the solar radiation that had been driving temperatures of 34 C to 36 C. While considering the pros and cons for grain crops, wheat did not dry as quickly on Wednesday to the 10 per cent moisture seen on Tuesday. For some, this will help keep harvest moisture in the 12 per cent range, while it may delay harvest in areas waiting for drydown. Smoke particulate matter can be harmful to human health. Protect yourself when working outside, and prevent long-term lung damage by wearing personal protective equipment. Take breaks and stay hydrated. Be safe out there.
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.
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.
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.
