OMAFRA Field Crop Report – June 2, 2016


Depending on planting date, corn is at the spike to 5 leaf stage and progressing well with the warm weather. Most corn acres received adequate rainfall for good emergence and an acceptable stand. However, dry conditions have prevented activation of pre-emergence herbicides on many acres. The high heat in the past week has caused weeds to grow quickly, so scouting to stay on top of weeds is important at this time.

In areas of the Niagara Peninsula with clay soils, patches of corn fields are leafing out underground. Planting occurred when the soil was dry on top but “gummy” underneath, and was followed by cold rain and cool temperatures. Many of these acres have low organic matter and are fields that had been in soybeans for a few years. If there is enough moisture to do so, replanting should occur on these fields if warranted.

When making decisions on replanting corn, consult the Ontario Corn Replant Decision Aid, an Excel file that can be downloaded from the “Interactive Tools” section of the homepage.

Corn leafing out under ground in Niagara region
Corn leafing out under ground in Niagara region


Soybean planting is essentially complete, and while emergence is generally good there are some imperfect stands. Similar to last year, lack of rain in recent weeks is causing poor emergence and some acres are being replanted. Some fields planted just before the cold rain on May 13 -14 especially on lighter soils and worked ground have suffered from reduced emergence.  When assessing a questionable plant stand it’s important to wait for all the seedlings to emerge. Do not rush when making a replant decision. Soybeans have the ability to adapt to thin stands.  If there are 100 000 plants per acre the field should be left alone (120 000 on heavy clay). If plant stands are very thin the best approach is to seed right on top of the existing stand.  The final population should not exceed 225 000 plants per acre as a maximum so a supplemental seeding rate of 125 000 seeds per acre is usually adequate.  Use the same variety if possible; this will reduce maturity differences in the fall.

 Again, there are concerns with activation of pre-emergence herbicides. Weeds have emerged before rains activated soil applied products, and re-spraying is required to control those emerged weeds. There have been reports of seed corn maggot feeding, especially where soybeans were planted into cereal rye or winter cover crops.


The first cut of alfalfa started on the weekend and continues through this week. The heat over the past week has quickly brought on biomass on what had been looking like a short crop. Alfalfa weevil is being detected, in the Niagara area as well as Chatham-Kent and the southern parts of Middlesex. Some producers are taking the first cut a bit early to avoid spraying for the pest, while others are spraying for control. New growth should be scouted for the pest. East of the 400 highway dry conditions are causing stress to show on knolls.

Winter wheat

Wheat is beginning to head out across the province and although it may be a bit short in stature, plants are bushy with a lot of tillers. There are reports of stripe rust in some areas of the province, particularly on fields that did not receive a fungicide application. Applying a fungicide at heading for Fusarium head blight control will provide control of stripe rust and mitigate the yield impact of that disease. Without an application of fungicide, stripe rust could cause a 30 to 50% yield loss depending on time of infection. Although there has been a lack of rain, there is still a lot of moisture in the wheat canopy and therefore high potential for disease development.  Much of the fungicide application for Fusarium control will happen in the next week. There are also some minor reports of wheat streak mosaic and spindle streak mosaic virus, which looks similar to stripe rust. If those symptoms exist but you cannot rub rust pustules off the leaf, it is likely the virus and it cannot be controlled by fungicide.

Cereal leaf beetle has been detected at threshold levels in traditional problem areas such as Alliston. The pest is appearing a bit earlier than expected.


Canola planting is wrapping up, with just the Cochrane area left to plant. Acreage is up by about 20% over last year. Some fields are moving beyond the 3 leaf stage now and have received herbicide, with nitrogen and sulphur top-dressing to come in the next week. Later planted fields should continue to be watched for flea beetle and all fields should be monitored for swede midge using pheromone traps. Threshold levels have been reached in fields in the New Liskeard area, and swede midge has been detected at lower levels in Renfrew, Elora, and across Grey County.

Edible Beans

White beans and other small seeded edible beans have been planted over the past week or more, with earlier pla

nted beans already emerged. While planting is now in full swing, in some areas producers are waiting for moisture.