Field Observations

July 3, 2025

Crops continue to progress as the calendar turns to another month. Be on the lookout for insects and disease, and take preventative measures to avoid yield impacts. Now is also the time to consider cover crop options for after the cereal crop harvest.

Corn

Corn is progressing very well with some heat and moisture, staging V7 to V10, with many fields knee high and canopying over.

As crops progress, now is a good time to look at fields overall. Are there areas of the field that are visually less than ideal? Now is a great opportunity for growers to dig up plants and identify the differences between the good sections of the field and the poorer sections of the field to help identify possible concerns. Make notes, so when harvesting and watching the yield monitor in the fall, you can quickly identify if it was the planting conditions restricting yield or maybe something else. Good information leads to good decisions.

One disease that should be on everyone’s watch list this year is tar spot. The ideal conditions for developing this disease are temperatures between 15 and 21 °C and high humidity (greater than 75 per cent) for seven to eight hours. Saturated soils (like many areas are seeing) and leaf wetness can cause the disease to spread quickly. Overall, it is wet/dry cycles that seem to drive development. Tar spot has been “spotted” already in the U.S. this year. It has historically been identified in Ontario in the first half of July. For more information on this disease and how to manage it, read the Grain Farmers of Ontario tar spot factsheet. The Crop Protection Network, supported by Grain Farmers of Ontario, also has a tar spot Crop Risk Tool that can help identify high-risk weather conditions.

Overall, as fungicide timing approaches and with the threat of tar spot (especially in areas that have experienced significant infections and yield losses), it is key to talk to retailers and schedule a fungicide application, as there are only so many sprayers and aerial applicators available in a very short window. There is always the opportunity to say no and pass on an application, but it is very hard to get added to a list as application timing approaches.

Keep in mind in the coming weeks as tassels start to emerge to scout for Bt resistant European Corn Borer (ECB). ECB is a destructive pest that has recently seen Bt resistant populations in regions of Canada.

Review this past GrainTALK webinar on other diseases and pests to be on the lookout for.

Soybeans

Soybeans across the province are staging V5 to V6 up to the R1 to R2 stage. Stage R2, where there is an open flower on one of the top two nodes on the main stem, is full bloom. Plants will typically stay in the R2 stage for eight to 12 days, at which time small pods will begin to form, transitioning the soybean into the R3 stage. Pay attention to areas that were waterlogged from past rainstorms; signs of wet roots may show up as the bottom leaves turn yellow or soybeans die. Excessive moisture can create uneven fields as low areas and compacted areas cannot achieve proper gas exchange in the root zone. Expect disease pressure to increase significantly in a short time frame.

Fungicide applications are occurring or will shortly if farmers choose to do so. Farmers are applying fungicides to help manage disease and potentially increase crop yield. Many fungicide applications are to help control white mould, which can affect the yield of soybeans. Certain varieties are more prone to infection, as are fields that were planted early, have a narrow row width, and have high plant populations. More information on white mould can be found here.

Be sure to check out the Pest Manager app (developed by OMAFA with funding from Grain Farmers of Ontario), which allows you to identify, map, and find integrated management options for common weeds, insects, and diseases in corn, soybeans, and cereal crops. Any pesticide use information in the app is specific to Ontario only, and users should always read the product label before use.

Read more about the challenging weeds of Palmer Amaranth and Waterhemp.

With wheat harvest just around the corner, 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 on what they suggest and what is available. The seeding rate should be increased to at least a population of 250,000 seeds per acre. 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 that the soybeans are going into good conditions. Getting soybeans in timely is critical, July 10 is a good date for wrapping up second crop soybean planting in the southwest, maybe July 20 in the deep southwest, but it is a risk at any date as success will be determined by weather conditions allowing for quick emergence and proper rains for plant development before the first frosts. The management of straw is critical; be sure to spread straw 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 one inch planting depth and hope for rain.

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

Cereals

Spring cereals are in stem elongation to heading stages.

Winter wheat fields are staging anywhere from GS 75 (milk) to GS 92 (ripe). When kernels are in the dough stage, they reach their maximum dry weight and are physiologically mature when the peduncle turns yellow. The kernel moisture drops from roughly 40 per cent to 30 per cent.

Winter wheat harvest will begin soon, as fields in the southwest are just needing the crop to dry down. Warm, dry weather will help ripen the grain. As harvest approaches, monitor fields closely for fusarium, and aim to harvest impacted fields first, and keep separate from fields that are not impacted by the disease. Ideally, if the field has been identified as containing Fusarium-damaged kernels, get the crop off as soon as it is mature, as nothing good comes from waiting. Also, if fields have been lodged, monitor and harvest first as well.

In preparation for harvest, watch this past GrainTALK webinar on harvest prep and maximizing your combine’s efficiency.

Cover Crops

Now is the time to be planning for cover crops once the cereal crop has been harvested. Cover crops can help meet several goals such as increase organic matter, suppress weeds, prevent erosion and more. The Cover Crop Selector Tool gives cover crop recommendations while taking into consideration individual field goals. This tool is based on Ontario research and is supported by Grain Farmers of Ontario.

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June 26, 2025

Crops are progressing nicely, and some corn fields will certainly reach knee high by the first of July. Disease and pests are still causing challenges across the province. Be sure to monitor and act when warranted.

Corn

Corn across the province is in the V5 to V9 stage. By about the V5/V6 stage (five to six visible leaf collars, or seven to nine full leaves), the tassel is initiated along with the harvestable corn ear. At around the V10 stage, if you remove the leaves from the stalk, including the leaf sheaves, you should be able to see some identifiable ear shoots! Now is the time not to cause any plant stress, as it will affect the ear development.

The number of kernel rows is determined on the main ear shortly after V5 to V6. The number of kernel rows is largely driven by plant genetics (maximum row number) but is influenced by the environment.

Tar spot is beginning to rear its ugly head again in the U.S., with the disease being identified as close as Indiana so far this year. In past years, tar spot has typically been identified in Ontario within the first two weeks of July.

A new tool is now available to help predict the risk of tar spot (to be used once the crop has reached V10) and northern corn leaf blight in Ontario. The Crop Risk Tool provides weather-based forecasting and risk assessments for various crop diseases (including tar spot and northern corn leaf blight), helping farmers to make data-driven decisions. The tool allows users to select the crop, location, planting date, and more to create a risk assessment. Even though this tool has been tested, visual scouting is still recommended. This tool is a Crop Protection Network (CPN) resource, which Grain Farmers of Ontario sponsor. For more information on tar spot identification, favourable conditions and control, view this Grain Farmers of Ontario factsheet.

Soybeans

Overall, soybean fields are looking good, with some fields canopying. This past week’s warmer weather has increased growth; soybean plants can be found around V4 (four trifoliates) to V6 (six trifoliates) to R1 (beginning bloom-plants have at least one open flower at any node) stages. Flowering begins on the third to sixth node of the plant and continues up and down the stem, and then to the branches. Three to four days after an individual flower opens, the flower petals dry out, and the pod begins to form.

Excessive rains in some areas last week created flooding and water ponding. With excessively wet soils, keep an eye out for root diseases, such as rhizoctonia and fusarium, that potentially affect these fields. Tolerant varieties should give good defence, but standing water will affect these plants. More information on identifying these two root rots can be found here.

Be sure to check out the Pest Manager app (developed by OMAFA with funding from Grain Farmers of Ontario), which allows you to identify, map, and find integrated management options for common weeds, insects, and diseases in corn, soybeans, and cereal crops. Any pesticide use information in the app is based on research from Ontario, and users should always read the product label before use.

Some challenging weeds are being identified in fields. Read more about Palmer amaranth and waterhemp.

Fungicide timing is approaching for white mould control. The key to getting the most out of fungicide applications is timing. Risks for white mould include the field history; if there is a known history of white mould, then the chance of it reoccurring 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/humid, and moisture is on the plant most of the day, there will be a higher risk of white mould. Listen to what Horst Bohner, OMAFA soybean specialist, shares on white mould last fall as he looks forward to this year and white mould concerns in this GrainTALK Webinar (around the 16:23 mark). The Sporecaster App can help you determine your field’s risk level. Fungicides can lower the severity of infection; however, timing is critical. The timing of application 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.

Soybean aphids are sometimes found in fields around this time of the year. Typically, aphids found earlier in the season will build up populations through the year. Although weather can alter the population, more importantly, is the population of beneficial insects such as ladybugs. If aphids are identified, also take note of the beneficial insects. The Aphid Advisor app is a great resource for identifying if the action threshold has been reached.

Cereals

The winter barley harvest is expected to begin in the next few weeks.

Fields are moving closer to harvest, with fields staging up to the dough stage (GS 80 to 87). Growth stage 87 is hard dough and is physiological maturity. Physiological maturity is when the peduncle of the wheat plant turns yellow, the kernels have reached this maximum dry weight at this point. With these past warm days, the grain fill period will be shortened. Ideally through the grain fill period, cool nights are experienced to help slow the maturation of the crop. Some rain later on this week would also be ideal to help with kernel sizing, as there are cracks in wheat field soil from the crop sucking up moisture.

In winter wheat fields that were not sprayed with a T3 fungicide, scouting should be taking place to access levels of fusarium infection in fields. If high rates of infection are noted, harvest those fields first.

Spring cereals are heading out right now. Be sure to scout for stripe rust as it was present in winter wheat due to overwintering in the area. If there is stripe rust present in fields, please connect with Joanna Follings, OMAFA cereals specialist, as she is collecting stripe rust samples for analysis.

Cereal leaf beetles are being found in fields, at threshold levels with spraying occurring in pockets across the province. For more on this pest and threshold levels read additional info here.

Cereal aphids that were found in winter wheat are moving to spring cereals, infection from the insect can cause barley yellow dwarf virus  (BYDV) in cereal crops. The Cereal Aphid Manager App can help with a decision on whether to take action. Always read and follow product labels, paying particular attention to pre-harvest intervals.

During this these past couple of weeks, the Ontario Cereal Crop Committee winter wheat trials are being inspected during the final stages of grain fill by collaborators and sponsors. Inspections are indicating large differences in variety tolerances to the disease pressure this year. Leaf rust, stripe rust and BYDV are the key diseases showing up. Trial results will go live on GoCrops.ca later this summer. Are you interested in learning more about the wheat breeding process? Read more here.

Managing drift

Join Dr. Jason Deveau, in this GrainTalk webinar, as he shares insights on off target pesticide movement, strategies to limit movement, and more. You can also visit www.bedriftaware.ca for more information on reducing spray drift.

Proper clean out for harvest to avoid grain contamination from treated seed

A reminder that grains or oilseeds contaminated with treated seed or other foreign material put domestic and export grain markets at risk. Using equipment that has handled treated seed can be a leading source of contamination. Read more about reducing the risk of contaminated seed in this Grain Farmers of Ontario factsheet.