7 min read

The Cropwalker - Volume 2 Issue 21

Always read and follow label directions.

To become a member and receive all issues, sign up at:


After becoming a member, you can view past members only issues at newsletter.fieldwalker.ca, plus any future issues will be emailed directly to your inbox.

Crop Conditions

Weather - Continues to be wet across Eastern North America. We are at 80-90% of 30-year average of accumulated CHUs. We are collecting about 100-110 CHUs per week. It takes about 150 CHUs for corn and soybeans to emerge after planting. Some areas of Ontario have not started planting and will not for at least another 7 days. Predicting weather in S Ontario this time of year is not very accurate. If you are planting in the evening, and they predict good weather the next day, don’t count on it. Winter wheat - A significant number of acres that were intended to be sprayed off have been left. Wheat is heading out in many areas. Many areas have earliest wheat at flag leaf. Current weather, shortness of straw and shortage of straw suggests you do everything to get fungicide applied to wheat. Corn – earliest is at 2-3 leaf stage, but not much of that. Soybeans – Planting is from 50% done to not started. Earliest are emerging. Spring grain and new seeding – earliest fields are near ready to spray. A lot more acres this year as growers switch from soybeans to cereals for forage. Other - While crusting should not be a problem, if sun comes out crusting can occur, especially on land that received pounding rains. Check your fields. If the ground moves under your foot when you walk you should be okay.

Forages- Weather has allowed grasses to mature normally while alfalfa is later than normal. If your stand is mainly grass know that grass quality decreases faster than legume quality. Consider harvesting on regular calendar date. Yield will be low but by waiting both quality and yield will be low. If you are not harvesting as haylage, consider wrapping. Don’t think we are going to get hay drying weather.


Expected Corn Yield with Delayed Planting (From OMAFRA Publication 811 - Agronomy Guide to Field Crops)

The data is what it is. Wish numbers were better. This is presuming normal weather from now until end of September. You have to weigh continuing to plant corn and projected price vs. switching to soybeans

Table 1 - OMAFRA Delayed Planting Corn Yield Expectations

USAB (Unseeded acreage benefits)

For some of you this may be a reality. Talk to your adjuster for specifics for you. Here is one example. Grower has an average farm yield (AFY) for corn of 150 bu/ac. His situation his USAB would be 1/3 X 150 = 50 x $4.75 or $237.50. He designated corn as his main crop. He needs feed so decides to carry on planting soybeans. He can plant a cover crop (if approved by adjuster) and harvest this for feed this summer. (A lot more details than I have written here. E.g. all spring seeded annual crops must be insured) for more details go to Unseeded Acreage and Reseeding Benefits (grains and oilseeds) feature sheet

Corn Yield at Various Populations

Corn is emerging variably in some fields. The table gives some indication of expected corn yield with various populations. I put this table together extrapolating from older research and higher populations. This table refers to expected yield if corn is planted before May 10. Different numbers apply to earlier and later plantings. If you have 20,000 good plants suggest leave it. It is next to impossible to “thicken” a corn stand.

Table 2 - Corn Yield by Final Population (Compared to Optimal)

Corn Yield Loss Due to Uneven Emergence

Research shows that individual plants that emerge 10 days late will have an 8% yield loss. Individual plants that emerge 21 days later have a 10-20% yield loss. If you have plants that are 2 leaves different, there will be a minimal yield loss. Plants that are 4 leaves behind fall into the 10-20% loss. If 20% of corn plants are 4 leaves behind the rest this could be 5-10% overall yield loss. If 20% of the plants are 3 weeks delayed emerging you should find out why.

Spraying 28% Nitrogen on Emerged Corn – Research from 1974-76 at RCAT indicates relative yield at various stages. 100% yield was with 200 lb/ac nitrogen, PPI. Thus, as you reduced the rate or sprayed post, yields went down. There was a slight yield increase by increasing the rate of N when spraying post. Thus, spraying 2-4 leaf corn yielded more when spraying 200 lbs vs. spraying 140 lbs. I am not sure of all the dynamics going on. It indicates a yield loss by spraying 28% N plus herbicides once the corn is up.

Table 3 - UAN on Emerged Corn

More on Horsetail control

The longer you let horsetail grow before you apply Roundup the better the control. Super high rates of Roundup (3.0 L/ac) give better control than 1.0 L/ac. So Broadstrike plus 3.0L /ac Roundup should do a decent job on those patches. (Please note that you cannot apply Broadstrike in-crop on soybeans)

Planting Soybeans in June

Unlike corn, planting date does not have a big effect on soybean maturity date. Maturity date is more affected by variety. Presuming you have the right maturity there is no reason to switch varieties until mid-June. But you want the canopy to close as quickly as possible. This means that you should increase seeding rate by 5-10% when planting in June. If you have a choice narrow row planting also helps close canopy quicker. Seed treatment is less of a factor when planting in June vs. early May planting. The presumption is that planting in June will result in quick emergence. You should plant soybeans into at least ½” soil moisture. I like beans to be at least 1-1.5” deep.

Nitrogen Stabilizers and Rates -  The next best option to splitting your Nitrogen applications in corn is to add a N Stabilizer with your PRE applied urea or UAN. 1. Agrotain Ultra is a liquid product that can be added to UREA or UAN – it contains a urease inhibitor and offers “above-ground” protection of N loss by volatilization. Its application rate is 3.1 L/mT of urea, and 1.55 L/mT of UAN. Agrotain Advanced is a more concentrated version of Agrotain Ultra and performs better on Urea. 2. Agrotain Plus SC is a liquid product that can be added to UAN. It contains a urease inhibitor and a nitrification inhibitor, so offers “above” and “below” ground protection of N loss from volatilization AND denitrification.   Its application rate is 11 L/MT. 3. Entrench is a nitrogen stabilizer that contains nitrapyrin, a nitrification inhibitor. It offers “below ground” protection from loss. Its application rate is 1.1 L/ac. It has a per acre rate, while both Agrotain products have a per treated product rate.

Table 4 - Common Nitrogen Inhibitors in Ontario

Cobutox/Embutox on Seedling Alfalfa

Cobutox or Embutox tends to be applied on the late side, time gets the best of us. Label states 1 to 4 trifoliates for crop safety purposes. Can go earlier, better to base on weed stage than alfalfa stage, but if possible, would not recommend going later than 3 trifoliate.  Controls Lamb’s Quarters, Pigweed, and Ragweed. Add 28 mL/ac of MCPA Amine to improve control of Wild Mustard/Vol. Canola.

My soybeans are emerging, and I don’t have my pre-emerge applied?

Given that planting is happening into a full profile of moisture, and we are likely to be doing this in warmer conditions than normal, you may see plants come out of the soil faster. Or, you are unable to get herbicide on, as you are trying to dodge rain showers. In either case, if you are growing non-gmo or IP soybeans, don’t be afraid to spray pre-emerge herbicide if a small percentage (up to 10-20%) of the soybeans have started to crack through the ground. Increasing water volume can help with reducing the risk of injury. A small loss of plants is much better than dealing with a mess of weeds in-crop. If more than 20% are starting to come through, ask your supplier prior to applying.

Can I spray weeds out of established alfalfa?

Unless your alfalfa is one of the newer Roundup Ready options and it is a pure stand, the answer is no.

Work with Faba Beans?

I recently found the attached growth stage chart of the Manitoba Pulse and Soybean Growers. You can find it here; https://www.manitobapulse.ca/wp-content/uploads/2019/05/Faba-Bean-Growth-Staging-2019_Horz-v5_FINAL.pdf

How to improve forage quality and regrowth

It is one simple adjustment. Raise your cutting height. If you have high ash content in your feed, it could be because you are cutting your forages too low. Leave at least 3” stubble. Volume may suffer a bit, but this will be made up in better quality and faster regrowth. These recommendations assume you have some grasses in the mix. If a pure alfalfa stand, 2-3” should be adequate.

Weed Control in Spring Cereals – What’s registered, what’s crops safe and what to control?

If you can spray it on winter wheat, it is crop safe on spring wheat and Barley. Oats are the most sensitive. Here is a list a list of the most common cereal herbicides.

Table 5 - Spring Cereal Herbicide Options

I’ve cut my 1st cut hay and didn’t get spring fertilizer applied, what should I put on?

Ideally you will have a recent soil test to determine P&K needs. At a minimum I like to apply 100 lb./ac Potash and 42 lbs/ac Ammonium Sulphate. If it is Alfalfa based, then 1 lb./ac actual Boron.  For hay with more than 10-15% grass content (other than Timothy), also consider adding 40-50 lbs actual N.

Table 6 - Hay fertilizer options following 1st cut

"In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual."

- Galileo Galilei