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The Cropwalker - Volume 4 Issue 21

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Crop Conditions

Weather we continue to collect heat units that is putting crops a bit ahead of normal. On May 28th parts of central Ontario had snow even though ground temperature was 3-5 degrees above zero. Some parts of eastern Ontario and central Ontario had frost one or more nights between May 27-29th. Wheat earliest fields have received their T3 fungicide which typically is 3 days after 75% of the heads have emerged. Ryan Benjamins CCA in Sarnia area says about 25% had their T3 last week and the rest are ready. Stripe rust is starting to show. (See note below from Albert Tenuta OMAFRA field crop disease specialist.) Corn earliest fields at 5-6 leaf stage. Areas that received frost typically plants are 3-5 leaves so should grow back if frozen leaves do not wrap growing point and not allow it to push through. The 8th leaf stage will come quickly. Check now for weed escapes. Soybeans in the frosted areas fields that were worked, or strip tilled and had little residue on the row fared much better that fields planted into a lot of corn stalk residue. One grower commented that another benefit of planting soybeans 3” to moisture meant they were not up when frost hit. If spraying dicamba on soybeans or corn check out https://www.engeniaspraytool.ca/ for help with spraying dicamba. You can allow it to use your location to give probability of an inversion event. BASF have a great web site. All fields must be checked for weed escapes.


Note from Albert Tenuta OMAFRA Field Crops Disease Specialist Just a couple of fields to date - Seaforth and Aylmer. Port Rowan was not stripe rust. Very low incidence and severity plus close to T3 fungicide plus very warm day and above 20C nighttime temperatures will reduce risk.

Fusarium reminders FHB timing. Once 75% of heads are emerged is day 0. The next 3 days, day +1 to day +3 are the optimum days to spray for FHB control. Prosaro or Caramba can be sprayed from day +1 to day +5. Miravis Ace can be sprayed from day 0 to day + 5.

Fusarium Head Blight Timing Scale

Day 0 75% heads fully emerged.

Day 1 – First flowers visible (they are yellow in colour)

Day 2 Anthers visible in middle of head

Day 5 Pollination complete.

Driver Weeds

These are the weeds that make or break an herbicide rec. Dandelions over 6”, glyphosate resistant fleabane, waterhemp. You get the idea. Then there are your table stake weeds. Lamb’s quarters, green foxtail etc… these are weeds that maybe controlled regardless of what herbicide program you use in Roundup-ready crops. If short on time, focus on scouting for driver weeds, as these will pick your post-emerge herbicide program for you.

Insect watch

Aphids in wheat Ever year, we can probably find some aphids in every wheat field. There are numerous beneficial insects that control aphids. You need 15/stem before heading and 50 per head after head emergence to warrant control. They tend to build faster when it is hot and dry. I believe some rains will wash some of them from the plants. What about spraying for them when applying a fungicide? Naa Not a good idea. Adds to cost and reduces the number of beneficial insects.

Cereal Leaf Beetle This will be the week in areas that normally have this insect. There is an increase in the number of cereal leaf beetles. Most fields it is just a case of watching to be sure the numbers are low.

Alfalfa weevil some fields in the Niagara area have been sprayed. Other growers in various areas have noticed them. The larvae are active now. Once you cut alfalfa that pretty much gets rid of them. They are a one-generation per year insect. Over wintering adults become active from May through June, and females lay eggs in alfalfa stems. Eggs hatch in one to two weeks. Larvae emerge from the stem and begin feeding on the growing tips of the alfalfa plants. Mature larvae feed for two to three weeks before pupating Pupation takes place in small, silken cocoons that are spun near the base of the plant. Adults emerge after one to two weeks. Adults feed in the alfalfa for two to three weeks before leaving for sheltered areas and entering a summer dormancy period (aestivation). The adults over winter and emerge next spring.

Picture 1 - Insect feeding in alfalfa

Leaf over vs. Leaf tips vs. Leaf Collars

Occasionally I will hear various people in the industry talk about different corn staging methods when it comes to assessing growth stage. Now that we are well into corn herbicide timing, it is critical to ensure we are on the same page. Most herbicides labels in Canada use the leaf over method, in the United States, many labels will use either plant height, or the vegetative method. And yet others talk about leaf tips. Chart below from OMAFRA Publication 811 – Agronomy Guide to Field Crops. Most post-emerge corn herbicide labels in Ontario end at 8 leaf-over.

Figure 1 - Various leaf staging methods in Corn (OMAFRA Pub 811)

"I begin to speak only when I'm certain what I'll say isn't better left unsaid." — Cato

Permit for nutsedge control in corn

You can apply Permit to corn for control of emerged nutsedge. Typically, nutsedge is not through the whole field and you can spot spray areas. Permit is a group 2 herbicide that does control several broadleaf weeds. It is registered on several crops other than corn. Permit is a bit expensive to apply to the entire field, since it needs other actives to be a complete corn herbicide (i.e., to control grasses). In research trials the year after application Permit plots had about 25% the number of nutlets as the Primextra or glyphosate treated plots. Field experience backs up the fact that with Permit, there is less nutsedge the next year. Gowan usually recommends the 19 gr/ac rate. This rate will also provide residual control of weeds such as Common Ragweed, Lamb’s Quarters, Pigweed and Velvetleaf. It is not registered on soybeans, if sprayed on soybeans, you will have to replant another crop.

Spraying new seedings This is the week to do it on most farms. Alfalfa should be at the 1-4 trifoliate to apply 2,4-DB (Caliber, Cobutox, Embutox) 2,4-DB is the butyric form of 2,4-D. Young alfalfa plants cannot change the butyric form to the amine form. Once they get to the 4th trifoliate, they can change the butyric form to the amine form. Weeds and older alfalfa plants are killed by the amine formulation. It was originally registered at 0.8 L/ac. It was weak on common mustard. I worked with the company that figured out that adding 28 ml of MCPA Amine 500 would control mustard. But this small amount of MCPA was hard on alfalfa so the rate was reduced to 0.5 L/ac 2,4-DB when MCPA was added, and timing reduced to the 3rd trifoliate. Since then, spraying 2,4-DB at 0.5 L/ac has become a common use. This rate is not as effective but slows weeds down to let the alfalfa get ahead. Adding Crop Booster has become common to help the alfalfa through the crop response to the herbicide.

Spraying Oats, Peas Underseeded to alfalfa. There is no product registered to spray this crop mix. Using 2,4-DB is hard on peas. If the weeds are bad better to sacrifice the peas rather than the new seeding.

How temperature inversions form. During daytime hours, dry air naturally cools with higher altitude. Solar radiation warms the earth’s surface and, during days with little cloud cover, convection creates winds and gusts that transport air vertically. As sunset nears, the earth’s surface is no longer heated by the sun. As a result, the ground, and the air adjacent to the ground begins to cool more rapidly than parts of the overlying atmosphere. Heat from the warmer air is transferred back to the soil, creating a layer of cooler, denser air near the soil surface. This process creates a temperature inversion, where the cool air at ground level has warmer air above it through the very lowest levels of the atmosphere. (Notes from BASF)

Common Burdock is the Santa Claus Weed

Once Common Burdock is in the second year of growth, its hoe, hoe, hoe. As it is likely the only “herbicide” that is likely to take it out (or a shovel).

Picture 2 - Common Burdock (beat up with herbicide)

Horsetail control in corn and soybeans

Broadstrike is registered for corn and soybeans pre emerge to control horsetail. Broadstrike is registered post on corn but not on soybeans. According to Mike Cowbrough OMAFRA weeds specialist this treatment gives 80% control. It means you will notice something. The other option in corn is Ultim Distinct. Ultim is no longer manufactured but you might find some at your retailer. According to Chad Garrod with Corteva when I asked if they still produced Ultim” We do but it has been moved and targeted at the horticulture market. We brought out Steadfast IS last year. It is a 2:1 Nico to Rimsulfuron compared to a 1:1 in Ultim. It has the safener in it so no crop heat unit restrictions. No information on Steadfast and horsetail in Pub 75A. (From my experience in soybeans Reflex or Flexstar will some times turn it black). There are various sub types (varieties) of horestail. Some are better controlled with certain products than other varieties. Glyphosate has limited activity on horsetail. If you have spring cereals, 0.4 L/ac of MCPA Ester or Amine will set it back. Mike Cowbrough figures Lontrel is about 80% as effective as MCPA.

Rolling Emerged Soybeans

There is a slight benefit to rolling soybeans after they have emerged. It does punch stones down to make harvesting easier and will punch down corn cobs which can be an issue with IP soybeans Replicated work by Horst Bohner Soybean Specialist with OMAFRA has determined that it is most crop safe between the 1st and 2nd trifoliate. Excess stem breakage occurs at the 3rd trifoliate. Does it add additional yield? Maybe 1-2 bu/ac compared to rolling at planting, provided the timing and conditions are right.

The caveats to making rolling emerged soybeans work are 1) crop must be at least at the unifoliate stage, preferably at 1st trifoliate, 2) topsoil should be dry, 3) less or no stem breakage occurs when rolled on days with full sun in the midafternoon (plants are flaccid), 4) use a smooth roller.

Fertilizing forages after first cut

A good stand of forages can remove 50 lbs/ac phosphorous and 250 lbs /ac potassium. This is equixvalent to about 150 lbs/ac Map and 425 lbs/ac 0-0-60. So depending on how much you have already applied will determine how much you should apply now. A generic recommendation is 75 lbs/ac MAP and 200 lbs/ac 0-0-60. If you have not already applied sulfur consider adding 15 lbs/ac S now. This is also a good time to apply 1 lb/ac actual boron (if you replaced your 200 lbs of Potash with Aspire (0-0-58-0.5 B), this would get you the 1 lb of boron. If using other boron sources, ask what type they are using and when it will release for crop uptake.


This spring if there is only one podcast episode you listen to, it is the AgTech So What episode with Jana Hocken of Lean Dairy Farm.

Lean Farming - Jana Hocken brings Toyota’s model to agriculture — AgTech So What Podcast

Lean Farming - Jana Hocken brings Toyota’s model to agriculture — AgTech So What Podcast

Jana Hocken is a dairy farmer and “lean farming” consultant. After an international career in engineering at Toyota, Jana moved to farm in New Zealand with her husband. At the time, she knew very little about agriculture, but she quickly realized that the principles of lean could also be applied at her own farm….and on many others.

In this episode, Jana spokes about using LEAN methodologies she learned while working as an Engineer for Toyota, and how she implemented LEAN best practices on the farming operations her and her husband operate. Jana speaks about how the adoption of these best practices improved employee performance, time management, and financial results.

So how does this apply to a cash cropping or agronomy related business? From what I gathered, it can be very simple to start with, like creating a visual dashboard on what the business goals are and eliminating or minimizing processes that do not help to achieve those goals. Having a set meeting, starting with a safety meeting, to nudge the business through the growing season, and ensure all staff are aligned.

Here are some examples from my perspective.

Using a machine data management program like John Deere Operations Centre or Climate Fieldview, allowing you to easily view and share field locations/problems/plot data within the field with others. Especially critical when you may not be able to meet in person due to COVID-19 restrictions. At a minimum you should be using standard field names, and boundaries, regardless of the software you are using.

Purchasing, trading, or adapting equipment to cover more acres or reduce the number of passes using the same number of hours (many farm operations are great at this).

Adopting farming practices that produce the similar yields but require less inputs (machinery, fuel, labour, fertilizer, seed).

Buying an updated planter allowed one client to check-off both covering more acres, and gaining section control, even though it is the same size as his previous planter.

Using an accounting system that minimize data entry requirements, and which can help forecast future cashflows/financial ratios to head off any problems with minimal effort.

Home - LeanFarm

Home - LeanFarm

As a lean consultant working around the world for over 16 years, I could see the opportunity for farmers to really benefit from applying lean principles to their farms. Thus began Lean Farm NZ. Our Lean Training program designed specifically for dairy farmers was rolled out to over 100 farmers across NZ in 2017.

Pre-Emerge and Water Volumes

This might be a comment for the 2022 planting season, but I thought I would share it now. You can apply rates of pre-emerge herbicides at rates higher than 10 gallons/ac. Growers that do apply at 15 gallons/ac, or more in some situations, have commented to me they feel they get much better weed control vs. when they had been applying at 10 gallons/ac. I feel this is especially the case in situations where the seed bed is maybe rougher than you would have liked, as the amount of surface area has significantly increased.

Watch Recropping Restrictions

With several new use patterns or having to battle weeds with the same mode of action, this is a reminder to check your re-cropping restrictions prior to making an herbicide application. Example: An application of two group 27s in the year of application in corn, can cause leaf bleaching in some classes of soybeans/edibles beans the following year.

Question – Jonathan, with expected warmer temperatures due to global warming, do you think that you will be raising crops further north?

Answer – No, just because the average temperature is higher, does not necessarily mean the cropping season will be longer. I am more concerned about the length of the cropping season for the types of crops being grown, than what the average temperature will be for the year. The first and last frost determine cropping season more than the average temperature.

Question - There is lots of noise on ShieldEx, where is it a fit in my corn program?

Answer – ShieldEx is a group 27 herbicide made by Gowan. It is a post-emerge grass and broadleaf product with limited residual activity. It is crop safe on all types of field corn, sweet corn, seed corn and popcorn. This maybe a good option for you if you have used products in the past like Accent Total or Ultim Total.

Question - Lontrel label suggests it has limited residual activity, what should I take mix it with?

Answer - My pick would be to do a tank mix of it with Callisto GT plus 0.25 L/ac of Aatrex for what I would hope to be a one pass broadleaf herbicide program that is strong on the thistle species.

Tillering in Corn Project

If tillering in corn is of interest, here is a project out of Kansas by Rachel Veenstra, PhD Student at Kansas State University. Rachel’s PhD thesis is to try and better understand the impact of tiller development in corn grown in low-population density environments. Rachel is hoping to complete the following as part of her study; 1) quantify relationships between tiller, main plant, and full plant aboveground biomass and yields of corn under various plant density scenarios; 2) identify potential traits, environments, or management strategies responsible for determining these relationships; and 3) create a base framework for predicting tiller development and determining final yield outcomes.

I became interested in Rachel’s work when I saw her posts on Twitter, and then noticed some of the same effects in corn hybrids that had lower than expected final populations (~20,000 plants), causing them tiller more than normal.

CORN TILLER 101 | The Tiller Queen

CORN TILLER 101 | The Tiller Queen

A tiller is an upright shoot that develops from nodes that are compressed in a specialized stem base structure (called a crown) of a plant. In corn, for example, these would be nodes 1-5.

Picture 3 - Tillering in Corn at approximately 20,000 plants/acre
Picture 4 - Cob on corn tiller

Frozen corn, soybeans, and wheat from my records here are other dates where we experienced frosted corn; May 14, 2001, May 22, 2002, May 25, 2006, May 20, 2009, May 15, 2015. There was one event of frost on June 21st in the 80’s. I remember the fields but not the year. This event covered various areas of Ontario and probably parts of fields in a larger part of Ontario. Corn at the 3-leaf stage will grow back. Corn at the 5-leaf stage is probably alive but you have to watch if the leaves that are frozen fold over the whorl and do not allow the corn leaves to expand. You can try various things such as rotary hoe or aggressive harrowing to try and get the leaves to unfurl. Corn at the 6-7 leaf stage may not make it. Key is to check all fields, especially low-lying areas whether around the outside or middle of the field. Sometimes knolls will also be hit. A number of fields have sun burnt leaves which appear grey-white. Frozen leaves will appear dark brown to black once the sun hits them.

Picture 5 - Sunburnt Corn Leaves
Figure 6 - Sunburnt Corn Leaves
Figure 7 - 2006 Corn Hit by Frost and Recovered

Soybeans fields that have a lot of trash, i.e., no till, will have more damage. Fields that were in corn last year and had aggressive row cleaners, strip till, or some conventional tillage are not as frozen. Plants that are just emerging should be ok. Check the growing point. You can have plants that have the cotyledon leaves frozen, but growing point is alive.

Figure 8 - Expect these Soybeans to Survive

Wheat There are lots of fields that had frost on the heads as they were emerging. The book says these may be at risk. BUT the years mentioned above when we had frozen corn, the wheat was not affected. Even the year when we had frozen corn on June 20.

Figure 9 - Frost on Wheat Wheat

When checking fields for alive plants mark an area in the field with flags or stones and go to the same spot each time you revisit the field. After marking with flags, you could also mark the location with John Deere Operations Centre or Climate FieldView using Pins. This makes it easier to for other people to find the affect plants if you want to share the location. (Patrick Lynch)

"I begin to speak only when I'm certain what I'll say isn't better left unsaid." — Cato