Field work progressed quickly across the province in the past week, with sunny skies and warm temperatures peaking on Friday, May 16^th before scattered showers and below seasonal temperatures began on the Victoria Day long weekend. Widespread rainfall slowed field activities beginning mid-week. Soil temperatures have generally been cool, resulting in slow crop emergence and growth.

Cereals

Winter wheat is at partial or full flag leaf emergence to boot stage in much of the southwest and anticipated to reach flag leaf emergence in Eastern Ontario in the coming days on early seeded wheat.

In terms of disease, there continues to be low overall risk of stripe rust and leaf rust due to minimal U.S. spore load; however, local risk is high where rust has been confirmed as it likely overwintered.  Powdery mildew continues to be present at moderate to high pressure in thick stand or susceptible varieties. Scouting is critical for managing these diseases. Wheat Streak Mosaic Virus has been confirmed in some fields; manage volunteer wheat to reduce wheat curl mites and avoiding early planting. Barley Yellow Dwarf Virus has also been confirmed in some fields.  Avoid planting too early and use insecticide seed treatments where required to manage aphids.

Ahead of T3 fungicide timing, ensure tanks have been cleaned thoroughly to prevent crop injury, especially after corn and soybean herbicides.

Manganese deficiency has been noted in some fields this year. Issues are more prevalent on clay soils, and those with pH and lower soil organic matter. Look for interveinal chlorosis on new plant growth.

Spring cereals are emerging evenly. Growers are encouraged to monitor staging closely for optimal herbicide timing.

Forages

There was a push on winter cereal forage harvest ahead of Wednesday’s rain (Figure 1), with winter triticale harvest beginning and many acres of winter cereal rye harvested in more southern counties. Winter rye is at the right stage for harvest in Eastern Ontario, but the weather has not been cooperative and many acres are yet to be harvested.

Dairy first cut haylage is just starting in more southern parts of the province. Cool conditions have slowed alfalfa development. Cutting decisions are being made with an eye to the weather forecast.

Corn

Planting progress estimates range from over 90% complete on coarse and medium textured soils, to between 30 to 50% complete on clay soils. Fitness of clay soils for planting has been a challenge in some pockets, with slow drying below the top couple of inches. Some growers on clays opted to focus on field preparation ahead of this week’s cool and wet forecast, with intentions to plant in the next window.  

Emergence of corn is in the range of 75% in the deep southwest, with the earliest corn at the 3-leaf-tip stage (Figure 2). Eastern Ontario is 10 to 25% emerged.

Soybeans

Between 20 to 60% of the soybean crop has been planted, depending on region and soil type, while some clay areas haven’t had any seeding done yet.

Soybeans planted in late April have just emerged. A few fields have required replanting despite no visible crust. Cold, wet conditions can lead to disease, reducing seed vigour or causing rot. Imbibitional chilling injury (ICI) differs from prolonged cool, wet weather. If very cold water enters the seed shortly after planting, it can reduce vigour. ICI is most evident when cold rain follows very shortly after seeding.

Canola

Winter canola in areas north of Guelph and in Eastern Ontario is flowering, while winter canola in southern counties is in late bloom/early pod stages. Fungicide application for white mould should be timed for 15 to 20 flowers on the main stem, when flower petals begin to drop.

Weed Control

Herbicide applications in emerged corn have been ongoing where possible. There are reports of a few identity-preserved soybean fields that have emerged before herbicide applications were made. If glyphosate-resistant fleabane is present in those fields, there is no remedy.

Growers are encouraged to double-check herbicide tolerant traits of their crop varieties before spraying to avoid crop death.

Agricorp

The federal and provincial governments have extended the deadline for new and existing AgriStability customers to secure 2025 coverage to July 31, 2025. Please refer to the website at www.agricorp.com for current information.

Breakfast Meeting Notes

Exeter (May 20^th)

Cereals

• Stripe rust was found near Mitchell, Ontario and leaf rust near Meaford. Overall risk to growers is low with the spore load coming from the U.S. being low so far; however, around those fields is was identified the risk is high because it likely overwintered. Growers in those areas need to be diligent with scouting.
• Wheat Streak Mosaic virus has been confirmed. The biggest thing is to manage volunteer wheat that serve as hosts to the wheat curl mite. If possible, create a two-week gap of host tissue availability (i.e., between wheat harvest and wheat emergence in the fall) to reduce the number of wheat curl mites. Avoid very early fall planting of winter wheat.
• Barley yellow dwarf virus has also been confirmed in fields. Insecticide treatments will help with managing aphids and avoid planting too early. Early planted crops such as winter barley and triticale are at higher risk because of early planting dates.
• Powdery mildew at moderate to high pressure in fields with thick canopies and susceptible varieties – keep on top of scouting. T2 fungicides are going on.  Rust is much worse in terms of yield damage compared to powdery mildew.
• Questions coming in about how late herbicides can be applied. If flag leaf is emerging and no herbicide on at this point, it’s too late. 
• As we get closer to T3/FHB fungicide timing growers/applicators are reminded to be careful with tank clean out – be sure tank is thoroughly cleaned to avoid injuring wheat especially if spraying after corn/soy herbicide apps.
• There has been some confusion about waiting for things to warm up to apply 28% UAN (Urea Ammonium Nitrate-nitrogen).  This is not necessary.  Dry foliage is the safest time to apply 28%.  Light mist is actually worse.  The most damage occurs when applied on white frost.
• Spring cereals are emerging nicely.
• Triticale forage harvest has begun. Growers are doing a better job at identifying the staging of the crop and harvesting at ideal timing for maximum quality.

Mn Deficiency

• Mn Deficiency is evident in some fields this year.  It often occurs in the same fields year after year. It’s more prevalent on clay soils, higher pH and lower organic matter (OM).  Look for interveinal chlorosis on new plant growth.
• It’s important to look at the Mn Index value not just the soil test ppm for Mn. The index is the accredited OMAFA soil test and takes into consideration the pH, etc. A value of less than 15 means the field could show a deficiency. Foliar application is still the best way to correct a deficiency since Mn is easily tied up in the soil.  The Zn test also uses an index value.
• Soybeans are highly susceptible to Mn deficiency.  Many soybean growers that have Mn deficient fields see issues every year, so they apply Mn annually even before significant visual symptoms are evident. 

Corn

• Essentially all corn is planted in this area.  There are pockets in Lambton, Niagara, and the St Thomas area where corn still needs to go in.  Niagara is not in bad shape.  Not as much field work is finished in Bruce county.  Quebec is also further behind.
• The USDA weekly crop reports, as of May 18, 78% of corn and 66% of soybeans planted across the US.  These numbers are well above the 5-year average.
• There is a wider spread of planting dates this year which will require careful attention to growth stages when it comes time to spray foliar fungicides.
• If corn did get frozen off, count those leaves when staging for weed control.

Soybeans

• A large percentage of soybeans have been planted in this area. Cold weather has resulted in very slow emergence. The last few years growers were used to fields emerging in 2 weeks but this year it’s taking much longer. 
• Beans planted in late April have now just emerged. Some years it can take over 40 days or more for all seed to emerge. There have been a few fields that needed to be replanted even though there was no obvious crust.  If the seed sits in cold wet conditions, diseases will attack the seed and reduce vigour. In extreme cases seeds will start to rot.
• Imbibitional chilling injury (ICI) is a separate problem from prolonged cool wet weather.  If extremely cold water is taken into the seed within the first few hours of being in the ground, it can affect seed vigour. A soybean seed’s moisture content will go from about 13% at seeding to 50% within a few hours. It’s during this initial stage of rehydration that seed is vulnerable to ICI. There are a few factors that impact the extent of ICI including the rate of water intake, seed moisture, seed quality, and variety. Cracked seed coats are much more susceptible to ICI. The clearest examples of ICI occur if a cold rain follows immediately after seeding.
• Experiments conducted in Ontario have shown that if soil conditions are fit and no rain is immanent the risk of ICI is low.  In some experiments soybeans were planted at 3 degrees C followed by freezing nighttime temperatures with no impact on final plant stands.
• Growers should not wait for warmer temperatures to plant considering that it’s May 20^th if soils are fit (dry). This is the right time to plant soybeans and there is no guarantee that planting won’t be delayed for weeks if a planting window is missed.  Nighttime temperatures are not cold enough now to wait.
• There are reports of a few IP fields that have emerged before herbicide applications were made. If glyphosate resistant fleabane is present, there is no remedy.

Simcoe (May 21^st)

Weather and Soil Conditions

• Topsoil is dry on top, but barely fit (gummy) below the surface resulting in planting challenges in clay soils.
• Cool weather is affecting crop emergence with April planted corn taking over 2 weeks to emerge.  Corn planted in the warm stretch emerging in about 8 days.

Corn and Soybeans

• In general, planting is ahead of average for May 21^st with more acres than normal of corn and beans planted. 
• Corn planting is progressing, but emergence is slow due to cool soil temperatures and variable weather conditions.  Clay soils probably around 30 to 50% planted.
• Soybean planting is also underway, with an estimated 20 to 30% planted on the clay soils, although the range is between 0 to 50% depending on location and rainfall patterns. Many questions about post-emergence herbicide tank mix options.

Winter Wheat, Cereals, Forages

• Winter wheat looks excellent, with many fields at the flag leaf stage.  Disease pressure has been low. Apparently, the fusarium risk in the USA is higher than normal.  It will be important to get good coverage with fungicides and select proper nozzles.
• Oats are up and off to a good start and cereal rye being grown for grain has headed.
• Triticale and cereal rye forage harvest is almost completed and most of these fields will be planted to corn.  When applying N to these fields, consider crop needs and nutrients from manure. Winter cereal forage yields were excellent and better than expected, mostly due to an open fall, with good establishment, good tillering and no gaps between rows.
• A few fields of alfalfa were cut ahead of current rain.  Most dairy alfalfa forage will start next week.  Cool weather has limited alfalfa weevil damage, however regrowth after 1^st cut should be scouted for potential weevil damage. 

Herbicides and Fertilizers

• There are ongoing trials and evaluations of herbicide applications, with a focus on avoiding phytotoxicity.  Syngenta trial is established at C&M seeds looking at the “rule of 3” (3°C a day before, 3°C the day of and 3°C a day after spraying). They are looking at different rates and all possible combinations with phytotoxicity evaluation days after and followed through to harvest.  No issues reported on evaluations so far.
• Before spraying soybeans, ASK! Ensure the soybean variety will tolerate the chosen herbicide(s).  It’s not a good thing to suffer LDUSP (loss due to un-insured peril). It used to be glyphosate, but now there are a range of herbicide tolerant traits available, e.g. Enlist/Engenia/LibertyLink.
• Volunteer ‘PowerCore Enlist’ corn in soybean fields is not controlled by quizalofop (e.g., Assure II). Use clethodim (e.g., Select) before the 6-leaf stage for effective control. Do not tank-mix clethodim with 2,4-D or dicamba, as this reduces its effectiveness—apply separately.
• Do not tank-mix liberty and dicamba.
• Burndowns with even a little dicamba can cause damage to emerging soybeans.  Will depend on timing of application before planting and amount of dicamba in the burndown.
• The 2025 “Weeds Tour” will take place at the Elora Research Station on July 16^th. One stop will feature a control comparison for volunteer corn from cobs vs planted.

Tobacco and Vegetables

• Vegetable transplants and tobacco transplants are also in full swing, despite current cool weather.
• More acres of tobacco are being grown this year due to increased demand.  Extra transplants are in short supply.
• Asparagus yields are lower than last year due to early start and cool weather. Some fields have been mowed.
• High bee mortalities have been observed coming out of winter. 

Discussion Question – Should we plant beans on clay soils with forecast cold temperatures and rain? 

• Generally emerging crops have higher risk emerging through restrictive layers in clay soils – farmers get gun shy when past experience has affected yields. Past experience: heavy rains followed by heat and drying results in crusting, hard soils. If seed trenches weren’t properly closed at planting, they will open up when soil dries and can significantly reduce stands.
• The mid-week rain with cooler temperatures, and next week predicted high around 20^oC and limited sun. 
• Seed will take 10+ days to emerge.  Suggestion for clay soils early in the week was to continue to prepare the ground if it was fit to work. Once conditions are fit again, newer equipment is capable of seeding a lot of acres quickly. If ground warms out in a week it reduces time to crop emergence and risk of restrictive layer – beans even more than corn.

Winchester (May 21^st)

Cereals

• The very early planted wheat is expected to reach flag leaf by the weekend. Some are still a week or more away from the flag leaf stage.
• Generally, fields are clean with low weed and disease pressure.
• Fields north of Highway 417 are averaging 4-5 days later than fields to the south of the highway.
• It’s suspected that the warm temperatures last week lowered any disease pressure that was approaching.
• Spring cereals are emerging. Growers are encouraged to monitor closely as herbicide timing will be approaching quickly.
• Spring cereal establishment looks good, with stands looking even.

Canola

• Winter canola in Stormont, Dundas and Glengarry is flowering this week. The few fields in the area look really good.

Forages

• Winter rye is at harvest timing in most of the region, but weather has not been cooperative for harvest. There has been some harvested, but still, lots in the field.
• Very few reports of first cut starting. Most alfalfa isn’t at bud stage yet, so growers are still planning on an early June first cut.
• New direct seedings look good and are progressing nicely.

Corn

• It is estimated that the region is 90% planted. Some growers are still finishing up or are waiting for fields to be fit (heavier soils, lower-lying ground).
• Rain was very variable across the region, ranging from 8mm to 18mm.
• Emergence estimations are also variable – along the provincial border, as much as 25% emerged, while around Kemptville/Winchester it’s closer to 10%.
• There isn’t a lot of pre-emerge herbicide expected – most acres have planned early post emerge programs.

Soybeans

• Estimated likely 50% of the bean crop is in. Growers that can plant both corn and beans simultaneously are likely closer to being completed, while others are still getting started or finishing up corn acres.
• Early planted beans emerged (First week of May planting).
• Not seeing any issues with crusting in soybean fields yet.
• No-till fields once again have high weed pressures this year. Growers are encouraged to examine corn herbicide programs or fall burndown programs to ensure as much control as possible.
• Many of the weeds found in no-till bean fields are winter annuals, and they are getting to be quite large.
• Rain this week is expected to bring another flush of weeds.

OMAFA Weather Summary: Thurs May 15—Wed May 21, 2025
 

Location	Highest Temp (°C)	Lowest Temp (°C)	Rain for Week (mm)	Rain Since April 1st (mm)	GDD0C April 1st	GDD5C April 1st	CHU May 1st
HARROW
2025	27.0	4.7	15.1	187.5	543	310	113
2024	30.6	10.0	5.1	157.1	669	412	161
2023	25.1	-0.3	11.6	75.9	542	298	96
10 YR Norm (2011-2020)	21.9	8.4	18.2	153.7	510	258	123
RIDGETOWN
2025	25.7	2.9	27.5	131.5	502	272	97
2024	29.8	7.8	20.7	164.0	620	368	153
2023	24.6	-1.6	12.2	126.3	509	273	92
10 YR Norm (2011-2020)	22.7	6.8	19.6	136.0	463	216	114
SARNIA
2025	27.0	2.6	18.1	169.6	485	260	90
2024	30.5	7.2	23.3	134.4	601	352	147
2023	25.6	-1.6	17.5	123.5	500	266	87
10 YR Norm (2011-2020)	22.0	6.0	19.2	135.4	439	193	103
LONDON
2025	27.7	3.2	27.0	170.1	489	271	94
2024	28.4	10.7	7.2	142.7	616	360	158
2023	24.3	-1.4	12.6	163.0	499	265	86
10 YR Norm (2011-2020)	22.6	6.1	19.5	141.4	452	209	110
BRANTFORD
2025	27.0	3.0	33.0	166.1	491	268	99
2024	28.5	8.9	7.3	108.4	573	322	147
2023	24.9	-0.3	19.3	139.3	487	251	90
10 YR Norm (2011-2020)	21.6	6.2	12.4	147.0	421	181	102
WELLAND
2025	26.4	2.7	23.6	107.4	499	273	106
2024	29.3	11.4	8.8	132.2	609	355	157
2023	22.4	-1.0	16.6	132.7	495	254	84
10 YR Norm (2011-2020)	21.9	5.7	16.0	155.3	457	212	111
GODERICH
2025	26.3	0.8	18.1	109.0	439	224	89
2024	25.8	8.4	14.7	133.6	535	292	143
2023	21.6	-3.2	23.0	108.4	436	218	59
10 YR Norm (2011-2020)	19.7	5.1	21.7	129.0	386	152	92
ELORA
2025	25.0	0.9	28.0	156.1	435	224	83
2024	28.5	8.0	7.9	135.5	513	272	144
2023	22.8	-1.2	11.9	118.4	431	212	75
10 YR Norm (2011-2020)	21.6	4.0	19.3	148.2	377	146	92
MOUNT FOREST
2025	24.8	1.2	35.5	134.8	432	224	79
2024	27.5	7.0	9.2	153.5	507	270	143
2023	23.1	-2.0	11.2	145.4	428	213	69
10 YR Norm (2011-2020)	21.5	4.4	18.1	131.6	366	143	90
BARRIE
2025	25.9	1.2	24.4	120.7	408	202	89
2024	26.8	6.7	5.6	221.1	480	242	133
2023	22.7	-3.2	25.9	146.5	421	201	70
10 YR Norm (2011-2020)	21.6	3.6	14.4	128.6	353	134	89
PETERBOROUGH
2025	25.8	2.2	28.9	135.2	445	229	95
2024	28.8	6.7	1.7	170.2	509	266	134
2023	22.5	-3.0	30.4	135.7	456	225	78
10 YR Norm (2011-2020)	22.4	3.7	12.7	130.9	391	160	97
KEMPTVILLE
2025	27.8	3.2	10.7	118.4	460	241	93
2024	28.0	10.9	12.4	175.6	532	289	161
2023	23.0	-2.7	17.4	193.0	479	252	83
10 YR Norm (2011-2020)	22.5	5.4	13.2	139.9	413	183	104
SUDBURY
2025	25.4	-1.1	11.2	103.1	314	140	80
2024	26.2	4.8	8.9	221.2	411	198	134
2023	25.1	-1.8	30.9	193.9	334	156	47
10 YR Norm (2011-2020)	21.8	3.2	15.9	132.5	269	100	76
EARLTON
2025	25.5	-2.9	7.3	89.4	273	115	74
2024	29.1	1.5	2.1	164.5	400	193	128
2023	25.5	-3.5	30.7	149.4	327	148	49
10 YR Norm (2011-2020)	20.8	2.4	14.3	104.6	234	87	72
SAULT STE MARIE
2025	27.2	1.9	30.5	140.3	315	134	76
2024	25.7	-0.3	10.5	186.1	394	166	112
2023	20.2	-2.9	5.4	127.6	332	152	51
10 YR Norm (2011-2020)	18.8	0.5	17.7	127.0	237	69	60
THUNDER BAY
2025	17.0	-5.4	7.2	120.2	240	87	46
2024	23.8	2.0	52.8	130.7	322	118	73
2023	25.8	0.0	29.8	121.3	261	103	63
10 YR Norm (2011-2020)	18.7	0.0	24.5	95.7	217	58	63
FORT FRANCES
2025	26.6	0.6	17.4	88.4	372	184	59
2024	22.2	1.4	59.9	122.4	354	140	94
2023	25.1	2.0	3.8	96.6	332	168	95
10 YR Norm (2011-2020)	20.1	0.6	20.2	87.5	262	85	79

This weather summary is compiled by OMAFA using Environment Canada weather station data provided by Agriculture and Agri-Food Canada. Data quality is verified but accuracy is not guaranteed and should be used for general information purposes only.  For additional locations and weather analysis, visit the OMAFA Pest and Weather System (PAWS)