Crop Report – May 16, 2024

Field Conditions

The season continues to be advanced of normal, which is especially evident in perennial and over-winter crop development. Crop heat units (CHU) and growing degree days (GDD) are significantly above the 10-year average, especially in southern Ontario. Progress for field work, particularly on heavier-textured soils has been limited due to frequent patchy rain, cool nights and overcast conditions. Manure application, fertilizer application, burn-down herbicide applications and tillage ahead of planting has occurred on well-drained fields as conditions allow.


Winter wheat crops continue to progress ahead of normal which has caught some growers off-guard when scheduling field applications for nutrients and pesticides.  Early planted fields and fields in the south are about 2 weeks ahead of normal and are at or near heading. Many will have T3 fungicide applied within the next week for protection against Fusarium.  Fields further north and east and later planted fields are about 1 week ahead of normal.

Barley yellow dwarf virus (BYDV) has appeared in early planted wheat, as well as in winter barley.  Spread by cereal aphids, the primary symptoms are stunting and discolouration of leaf tips (yellow, red/purple). Early planted wheat last fall, as well as fields surrounded by cereal cover crops, is at higher risk of infection. Insecticide seed treatment may need to be utilized if planting very early in the fall.

Physiological fleck is also appearing in fields and is often mis-diagnosed as a disease.  Some varieties are more susceptible and generally symptoms are more uniform across the field than diseases and do not move upwards in the plant like diseases such as septoria. 

Powdery mildew is appearing in winter wheat fields with thick canopies due to the wet weather.  Some infection is appearing on the penultimate leaf and has growers wondering about the need for control. In most cases, if the variety has some level of resistance to powdery mildew and is nearing heading, a fungicide application can wait until T3. There were differences reported in powdery mildew control between fungicides.  It is important to read fungicide labels to ensure the fungicide is labelled and has efficacy for the disease to be controlled.  An updated Ontario Crop Protection Hub is a great resource for comparing pest control options.  It is important to ensure the correct pest is selected when comparing products.

Stripe rust has been found in winter wheat in Essex (Maidstone), Chatham-Kent (Tilbury) and Elgin (St. Thomas) counties. The best defense against stripe rust is a combination of variety selection, scouting and timely fungicide applications. In Ontario winter wheat varieties, there are large differences in variety susceptibility to the disease. Growers should check with their seed supplier and the Ontario Cereal Crops Committee performance trials for specific variety ratings. If a variety has a rating of 6 or higher, the variety is susceptible to stripe rust and will benefit from a fungicide application if stripe rust is present. If a variety is rated 3 to 5 then it is considered moderately resistant and should be scouted for stripe rust regularly during the growing season. If stripe rust is present and appears to be challenging the upper leaves of the canopy in these moderately resistant varieties you may want to consider a fungicide application, particularly if the wheat is just at flag leaf. If stripe rust incidence and severity is low on tolerant varieties and growers are less than a week away from fusarium fungicide timing, then you can wait until T3 fungicide timing. If a variety in your area has a rating less than 2, this indicates that the variety is resistant against stripe rust and will likely not benefit from an early fungicide application.

Figure 2 Yellow-orange coloured lesions of strip rust are small, round, blister-like lesions that merge to form stripes.


Grasses and forage cereals are progressing quickly. Many fields of winter cereals intended for forage are beyond the flag leaf to boot stage where protein and digestible fibre quality is highest. Once the crop heads out, forage quality declines quickly. A second opportunity for cereal forage harvest occurs for whole-crop cereal silage at soft dough stage, much like corn silage.  The cereal can be chopped and ensiled in a tower, bunker, or bag. Soft dough stage is too late for bale age, since stems will poke holes in the bale wrap. Although highest quality comes with forage harvested at boot stage, the maximum energy harvested per acre occurs at soft dough stage.

Growers harvesting dairy alfalfa forage by the calendar will begin harvest within the next week.  Wet fields and busy planting schedules often give priority to timely corn planting, however timely forage harvest will give bigger economic benefit from a livestock nutrition perspective with higher digestible fibre versus higher lignin with later harvest.  It is easier and less expensive to replace the energy lost from late planted, lower-yielding corn than it is to replace lost digestible fibre from a late forage harvest.

Alfalfa weevil have been active in some fields in the south.  Regular scouting, looking for tip feeding with 2 to 3 active weevil per stem will determine what type of action is required.   Harvesting the field is the best option, however, watch for feeding on regrowth if larvae are small.  If the forage crop is not ready for harvest, then insecticide control for alfalfa weevil may be required.  

Manure application after forage harvest is a good opportunity to supplement nutrients removed by the crop, especially in forages that include grasses.  Application as soon after harvest, before regrowth, will provide best results, since yield will be reduced where delayed wheel traffic sets back new growth.  After application, alfalfa regrowth occurs at the apical buds on the stems and from the crown, but alfalfa regrowth damaged by wheel traffic will need to re-start from the crown. Taking a manure sample is recommended, since most manure applications to alfalfa forage crops will not replace the potassium that is removed by the crop.


Planting progress as of May 16th ranges between 25 to 40% completed, however this varies from regions where no planting has occurred to light soils where planting is close to completed.  Seed bed preparation has varied with spring rainfall where pounding early spring rains have left seedbeds lumpier than areas with fewer and gentler spring rain events.   Late April planted corn has emerged.  Producers looking at the calendar are asking about switching varieties. Switching to shorter season hybrids is not recommended until after May 25 if conditions continue to prevent planting opportunities.

Weed Control

Even when conditions will delay planting for several weeks, it is important to apply burndown treatments when weeds are small and actively growing. 

With delayed spring operations, there will be an overlap in spraying schedules across various crops.  Tank cleanout and communication with the spray applicator on what herbicide tolerant crop traits have been planted will avoid costly errors.

Agricorp wants to remind growers to report their acres as soon as they finish planting to avoid last minute rush.  Reporting can be done online or by calling in to the Guelph office.

Ag Breakfast Meeting Notes – May 14, 2024

  • Field conditions are generally wet, which has limited progress in the last two weeks. Rainfall has been patchy, but cool nights and overcast conditions have prevented soils from drying. Many farmers are getting frustrated because the forecast during the past two weeks has kept a lot of equipment parked, but then the predicted rain didn’t happen and neither did the field work.
  • Well-drained fields have had fertilizer application. Manure is being applied where soil conditions will carry equipment. Most fields that are not clay have had some prep work done.
  • Fertilizer applications are generally done on winter wheat. It has been too cold at night, or too wet to apply herbicides. Pre-harvest applications will be critical. Fungicides have not been applied either, but these will be important to manage disease pressure from the wet spring.
  • The spring cereals that have emerged look good so far. Reports of oat cover crops overwintering in the region have come in.
  • Estimates are for an early first cut this year, but it might be lower yielding. GDD accumulation is ahead of normal, which advances maturity on winter cereals, grasses (Base 0˚C), and alfalfa (Base 5˚C). For those who cut with the calendar, Victoria Day is an early May 20th this year.
  • Corn planting progress is estimated at 0-15% across the region. The only fields planted are well-drained and missed the rain.
  • Soybean planting has not really started yet.

Overall conditions

  • Sandy soils are fit for field operations, heavier soils remain too wet for most activities as forecast calls for sporadic rains towards end of week
  • Fields with cover crop rye are holding moisture, even when burnt down
  • Reports of excellent conditions for cultivation, planting in some areas, tough soils to get through in others


  • Very advanced development ahead of normal in south, not quite as advanced further north & east (ie. London)
    • 2 weeks ahead of normal in early planted wheat, 7-10 days ahead of normal in late planted wheat
  • Earliest wheat has heads emerging, T3 fungicide timing to start likely end of this week for fusarium protection
  • Powdery mildew is still an issue with wet weather
    • Some infection on penultimate leaf
    • In most cases, likely makes sense to wait for T3 timing with this close to heading
      • Could mean longer protection timing for stripe rust if it becomes a problem
    • Some differences reported in powdery mildew control between fungicides, ensure fungicide is labelled and has efficacy for disease to be controlled
  • Barley yellow dwarf virus has appeared in early planted wheat, as well as winter barley
    • Insecticide seed treatment may need to be utilized if planting very early in the fall. Check Ontario Crop Protection Hub to ensure that correct pest is selected when comparing products
  • Physiological fleck is showing up, common to misdiagnose
  • Sulphur deficiency is appearing in many fields without S fertilizer application and seems worse this year than other years
    • May be related to very early season growth nutrient demands outstripping soil supply of S
    • Some reports of differences in availability from thiosulphate vs sulphate source of S fertilizer
      • In general, thiosulphate takes more time to become plant available, may see deficiencies still if used at a low rate in wheat
  • Reports of cereal leaf beetle and armyworm moths being trapped
    • Below thresholds, but could become an issue for spring cereals
  • Check Ontario Crop Protection Hub to ensure that correct pest is input when comparing products


  • Reports of 15-25% of corn has been planted
    • Higher in lighter soils, much less in heavier soils
  • Late-April planted corn has emerged
    • Staging at VE-V1
  • Growers inquiring about changing hybrid maturities
    • In south, no reason to change until June 1


  • Minimal acres planted – 2-3% on lighter soils


  • Cereal rye is in head, triticale – head emergence
  • Harvest has begun


  • Burndown should be applied now even in fields with no chance of planting for 2-3 weeks
    • Small weeds are easier to kill
  • Control of Canada fleabane
    • Better to apply glyphosate + Eragon + metribuzin now for better control than using glyphosate + 2,4-D (which has inconsistent control)
    • Control depends on trait on soybeans
      • E3 soybeans – higher rate of 2,4-D used gives improved control
  • Field horsetail – manageable weed, but requires 5 year plus effort to control; best programs:
    • Wheat – highest registered rate of MCPA
    • Corn – MCPA + Broadstrike
      • Be very careful with crop staging when applying this mix, late application can have major impacts on yield
    • Soybeans – Dual + Broadstrike + glyphosate
      • Preplant only
  • Liberty + glyphosate – not recommended as the mix reduces uptake of glyphosate

GPS issues

  • Issues with solar storm over the weekend
  • Some issues still with accuracy have continued into this week
Mt Forest


While planting progress across the area varies widely and field operations are staking up, past experience has shown that everything will get in and come fall everything will come off. Based on work done in Ontario, corn yield reductions from late plantings are often overblown. Research at Ridgetown, Elora and Woodstock suggested 98% of yield potential by May 20th, 95% by May 25th and in Ridgetown even corn planted early in June showed yield potential of 95% of optimal planting dates.

Rainfall amounts in the last week have varied from trace to over 2” but very variable.

Despite the frustration of some whose field delays are stressing them out, we are ahead of many other areas of the province and there is still lots of planting season remaining.

Winter Wheat

The winter wheat crop looks good across the region. Growth stage of wheat varies, based on seeding date and geographic location. The crop is advancing rapidly, and scouting will be important to properly time different crop protection applications (e.g. fusarium head blight). Once the wheat crop has approached flag leaf (GS 37), herbicides should not be applied as the risk of significant crop injury will be greater than any advantage gained in weed control.

While the majority of the crop is looking excellent, a tough spring does show the issues of previous years like soil compaction, tillage, tiling, etc. Observe for these visual effects and manage accordingly.

Fertilizer is all on and it’s obvious from the leaf burn in some fields that applications during the recent cold spells may have done some hopefully minor damage if any. Check those fields so you know for next year.

Some fields are showing some Sulphur and/or Manganese symptoms and should be checked and addressed as needed.


Planting progress across the region is widely variable. Mostly a function of rainfall and soil type with areas that have completed corn to those who have not turned a wheel. Where corn has gone in the consensus was no more than 50% on average. About half the corn planted was likely under good conditions while the remainder may likely see some effects from the soil and moisture conditions once the crop emerges and starts to grow.

While people are starting to talk about hybrid switching, it’s too early unless people greatly pushed their maturity target initially. If less than 2800 CHU, not before May 15-20th and then move down by 100 CHUs per week. For 3200 CHU area the date is early June.

Early planted corn (late April) has emerged and looks great, but the acreage is limited.

 Winter Canola

Most in full flower and looking good. Appears to be another successful winter canola year. One issue to be on top of is reported cabbage seedpod weevil infestations near or at threshold in some fields, and this should be addressed sooner than later.  Advice on options for insect control in canola and other crops with the loss of some older insecticides is available here!


There are some in the ground, but the total acres are very low currently. Soybean topics for some thought include weed control, especially in light of the condensed season and the potential for mixed trait seed to end up planted in the same fields. Record keeping and communication with herbicide applicators is critical to ensuring all the effort to plant the crop is rewarded with good weed control and no crop losses due to herbicide product mistakes. Think of soybeans of different traits as being different crops and manage appropriately. Ie many corn herbicides are not compatible with soybeans, but now some soybean varieties weed control choices are not compatible between varieties.

Weed Control

 The use of high-speed vertical discs or cultivators to prepare the seedbed will often only injure perennial weeds but not kill them. This will significantly reduce the effectiveness of any burndown herbicide program applied after. Therefore, preplant burndowns to manage perennial should be done prior to any tillage operation. Certain herbicides prohibit incorporation with tillage as they may either reduce herbicide activity or increase the risk of crop injury. Refer to the product label for any restrictions prior to use. With the potential for sprayers to be working in several different crops in a short window, thorough tank clean out must be a priority. Clear communication with the spray application on what specific herbicide tolerant crop traits have been planted will avoid significant crop injury and costly errors. The custom spray operators are prepared to get it all done but communication and patience on everyone’s part will be important to the overall success of this critical part of crop agronomy.

If agronomists, growers and field scouts encounter weeds that they cannot identify, they can reach out to If they suspect that a weed population is resistant to a herbicide(s), there is a survey program coordinated by OMAFRA that will process samples at no cost. The submission form with the types of tests offered can be found at: If a specific test is not offered through this survey, you can contact the University of Guelph Weeds Laboratory at

Northern Ontario

Christine O’Reilly, Forage and Grazing Specialist, shared info on forages that is captured in the Crop Report at the top of this article. Mike Cowbrough, Weed Specialist, offered support on weed identification, molecular testing of weeds for herbicide resistance, and other weed control topics – contact him anytime. He described an awareness and demonstration program he is involved with on roadside control of wild parsnip by MTO. A question was asked about the efficacy of flame throwers for burdock control. Flame throwers burn above ground tissue which can be effective for annual weeds, but burdock roots must be removed to prevent them from growing back. Burdock thrives where there is a lack of competition, so focus on improving pastures to mitigate burdock establishment.

Regional Updates

Northeast – Temiskaming, Nipissing

-planters were out in April did a few hundred acres, others just out this week

– soils had been wet but are now dry on top, a lot of fields being worked now

-fair bit of corn completed and some spring wheat

-canola planned for this week

-recent rains are making soils it a bit sticky for this week

-planting window for crop insurance is starting to close

-winter wheat starting to elongate

-hay fields look phenomenal, lots of growth

Manitoulin & Algoma

– wet spring has delayed planting on the island

– spring cereals have been seeded on lighter soils

Weather Data – May 9 – May 15, 2024
LocationHighest Temp (°C)Lowest Temp (°C)Rain for Week (mm)Rain Since April 1st (mm)GDD0C April 1stGDD5C April 1stCHU May 1st
10 YR Norm (11-20)19.76.423.8141.9426203201
10 YR Norm (11-20)19.75.327.4128.8383163177
10 YR Norm (11-20)18.64.722.1122.1363146154
10 YR Norm (11-20)18.55.317.9128.0374158178
10 YR Norm (11-20)18.75.424.0144.1378161176
10 YR Norm (11-20)
10 YR Norm (11-20)17.53.319.1132.4307104137
10 YR Norm (11-20)16.83.719.4120.0296100134
10 YR Norm (11-20)17.22.816.3117.828592134
10 YR Norm (11-20)
10 YR Norm (11-20)
10 YR Norm (11-20)18.11.815.8120.320663106
10 YR Norm (11-20)18.00.610.293.317454108
10 YR Norm (11-20)16.00.514.8112.21844282
10 YR Norm (11-20)16.3-1.08.873.01673490
10 YR Norm (11-20)17.8-0.113.768.920352113

– winter wheat and winter canola off to good start

-forage growth is good, a week ahead of usual

– too wet to fertilize right now

Northwest – Thunder Bay, Rainy River

– conditions had been wet and not very warm, but soil is currently dry on top

-got rain yesterday which was not expected and slowed activity, chance of rain this morning

– less activity untiled ground, some corn has been planted and canola going in now

-plots went in this week at Emo research station

– cattle are in mud which is not common this time of year