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The Cropwalker - Volume 3 Issue 36

Always read and follow label directions.

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Crop Conditions

Weather parts of Ontario received a frost last week. Other areas just cold nights. In Central Ontario frost damage went from all corn affected to top parts of some corn plants frozen, Eastern Ontario had enough frost in many areas to kill corn and beans Winter wheat planting has started. Mainly after edible beans which are yielding very good. And some of the early harvested soybeans Corn – cold nights and even frost has slowed corn down but will not prevent nutrients being moved from the stalk to the ear. Every one is anticipating some very good yields in areas that received rain. Some top die back. This is because plants are moving nutrients to the ear from the stalk both top and bottom. Crop is still disease free. Soybean harvest is just starting. This is the week we will get a handle on how soybeans will yield. Early indications are fields ready to harvest are in the 11-13% moisture. Don’t wait for overly dry soybeans. There will be a tale of two soybean crops this year, those that had rain during grain fill, and those that didn’t. One grower in Clinton area reported 73 bu/ac on a 93-acre field. Another grower on the Perth Oxford border had 45 bu/ac. Not enough rain.


Pre-Harvest on Soybeans – What does the label say?

Check multiple labels. They all said the same thing. Maximum of 1 REL/ac of glyphosate (0.67 L//ac 540 gr/L concentration pre-harvest, with a 7-day pre-harvest interval. You can add a desiccant such as Eragon or Aim to improve dry-down of weeds, but you cannot cut the harvest interval shorter.

Corn Yield Loss from an Early Frost – This table gives an approximation of yield loss due to an early frost. There is a difference among hybrids. Also, frost can be worse in areas of the field so this will be reflected in different losses in different parts of the field. (Table from OMAFRA Pub 811)

Figure 1 - Yield Losses in Corn from Late Season Frost

How Do I Control Volunteer Wheat in Summer Seeded Alfalfa?

If you have significant volunteer wheat, especially behind the combine, you can spray with Venture or Poast Ultra or Select. Assure is not registered for alfalfa for forage. This will take out any seedling grasses, so it will only work on pure alfalfa stands. How long between spraying Assure and planting grasses. Assure was a DuPont product but has been sold. Hard to get technical information, but a consensus of people I spoke to feel that planting grasses 2-3 days after applying Assure should be safe.

Picture 1 - Volunteer Wheat in Alfalfa

Cold Sensitive and Cold Tolerant Weeds – Purdue researchers suggest that weeds are either cold sensitive or cold tolerant. Cold sensitive weeds do not readily take up herbicides after a light frost. Weeds in this group include dogbane (looks a bit like milkweed), milkweed and bindweed. Spray these before a frost. Cold tolerant weeds take up more herbicide after a good frost. The frost triggers the plant to store more nutrients. Thus, herbicides are translocated more/better than before a frost. Weeds in this group include dandelion, wild carrot, and quack grass. Spray these weeds three to four days after a heavy frost. Consensus is that perennial sow thistle is neither cold sensitive, nor cold tolerant. From my experience perennial sow thistle can be controlled any time now if you have actively growing rosettes. All of this must be practical. You cannot wait forever to get all the spraying done. If you spray and work the ground generally kill is improved.

How much sulphur will be available the following spring from MESZ?

Microessentials SZ from Mosaic is half sulphate sulphur and half elemental sulphur. The elemental sulphur portion release is controlled by three factors; soil pH, soil temperature, and soil organic matter. At one time Mosaic had assumed it was all released within one growing season, but this was based upon a study at a constant soil temperature (growth chamber) and does not reflect field conditions. As a rule of thumb, I would expect you to have 60-75% of the total sulphur available for the following growing season (if fall applied). Chart below as example for the oxidation of elemental sulphur in MESZ for Harriston, ON (pH of 7.2 and 4.5% OM).

Figure 2 - Estimated Oxidation of Elemental Sulphur for MESZ in Harriston, ON

Question If I apply sulphur in the sulphate form (S) this fall how much is available next spring? While I do not know of research measuring this, I estimate that at least 50% of fall applied S will be available next spring. S and N are similar in their soil loss patterns. We believe 50% of fall applied N is available next spring. Thus, we can estimate at least 50% of fall applied S will be available next spring.

Comment from growers over the years “If these soybeans ever get back to 16%, I am taking them off.” So why not start by taking soybeans at 16% now and gain the many benefits of an early harvest. By starting at 16% you may avoid harvesting soybeans that are too dry. The table below shows the penalty of delivering soybeans below moisture of commerce.

Figure 3 - Dollars loss per bushel for overly dry soybeans

Question How does controlling weeds before planting wheat help give a better red clover stand? Answer If there are no weeds especially winter annuals including Canada fleabane red clover has a better chance to establish. And, if you don’t have to spray weeds next spring red clover will be better off. When we used to work the ground before planting wheat we seldom had to spray for weeds in the spring. In that system we had good red clover stands. It is less expensive and just as effective to spray for weed control to get a good red clover stand. Reminder not all of your fields may be right for red clover next spring.

What are festulolium grasses?

Most alfalfa mixes have timothy or orchard grass. Some have meadow fescue. All to these grasses have weak points. Timothy only yields in the first cut. Orchard grass can be aggressive and kill out alfalfa if manured and seeded at a rate over 2 pounds per acre. The fescues are lower yielding. The festuloliums are trying to become a main grass component. There are numerous types of festoliums. There are some that are a cross between Italian rye grass and meadow fescue. These tend to be high yielding, palatable and high quality. Their weakness is stand longevity. They generally only last 1-2 years. They are great when you need a lot of feed in a short time. The other main types are a cross between tall fescue and perennial rye grass. They last longer but do not have the yield of the festoliums that are a cross between meadow fescue and Italian rye grass.

“Festulolium is the name for a hybrid forage grass developed by crossing Meadow Fescue (Festuca pratense) or Tall Fescue (Festuca arundinacea) with perennial ryegrass (Lolium perenne) or Italian ryegrass (Lolium multiflorum). This enables combining the best properties of the two types of grass."

Figure 4 - Festulolium crosses
Figure 5 - DLF Festulolium Diamond

From Charts and Quotes from DLF Forage Seeds White Paper on Festulolium - 2013

Question Can I plant winter wheat after forage sorghum. Answer from Joanna Follings OMAFR Cereal Specialist - The research on wheat after sorghum has found that there can be allelopathic effects on wheat causing yield losses anywhere in the range of 10-25%. However, there are many growers south of the border who routinely plant wheat behind sorghum without any issues. To minimize any allelopathic effect, here are a few things that can be done:

1) If soil erosion is not a concern, growers should till sorghum soon after harvest and delay wheat planting as long as possible to allow potential toxic compounds to degrade

2) Make sure fertility levels are adequate and use a starter

3) A 25% increase in wheat seeding rate can offset any decrease in seed germination and seedling vigor

These comments refer to planting wheat after grain sorghum. I suggest that there is less allelopathic with forage sorghum since most of the plant is removed.

Glyphosate on Alfalfa/Forages Pre-Harvest

I’ve had this question 3 or 4 separate times in the last week, so it’s time to put it in again. What can I spray to burndown alfalfa pre-harvest and how long do I have to wait until cutting it?

You can spray up to 2 RELs of glyphosate (1.33 L/ac Roundup Transorb/Weathermax) pre-harvest. This is the ONLY product you can use and feed to livestock. Cutting interval suggests 3-7 days. 3 days is likely adequate when you have excellent growing conditions for translocation. 5 days for nice days like this week. I would use 7 days for less than ideal growing conditions (such as when it looks like alfalfa was stuck in a fridge).

If you are using a non-Roundup brand glyphosate, read the label.

I want to terminate an Alfalfa stand, when should I cut or do tillage?

If you have quackgrass or thistles (anything with rhizomes), and/or are not ploughing, glyphosate required.

1.     Planning on cutting at this time of year? Spray pre-harvest

2.    Not cutting? Spray with a minimum of 100-150 GDD left in the season for translocation to ensure a good kill. Sooner than later is likely a good idea if there is enough regrowth.

If you have no perennial weeds, and are ploughing, no glyphosate required.

What can I add to my liquid wheat starter and be crop safe?

According to the South Dakota State University salt index calculator, you can add one of the following across all soil types and be crop safe if applying starter in-furrow. Note the crop safety of ATS, for adding 3 to 6 lbs of S per acre in the fall, it is NOT worth the risk of trying to blend a bit in. This was confirmed with past conversations I have had with The Anderson Group.

Figure 6 - Safe rates of liquid starter for John Deere or similar style drills

Are there situations where you don’t recommend Microessentials SZ for wheat starter?

Yes, quite frequently in these situations the retail does not carry Microessentials SZ (MESZ). Another is the grower has extremely low testing P levels and limited drill capacity, in which case sulphur dollars are better reserved for the spring.

For those using MESZ in the fall, since a portion of the sulphur dollars are being spent in the fall, you can cut back the spring sulphur rate slight to offset the premium between MAP and MESZ.

Question What is the issue with feeding sorghum after a frost? Answer If sorghum dies quickly because of frost there is a buildup of prussic acid. There are lots of reports and warnings. I have never heard of livestock illness due to feeding sorghum that was frozen. BUT better to be careful than sorry. 1) If frozen sorghum is harvested as dry feed or is ensiled the prussic acid level is low enough to feed. Suggestion is to do not feed frozen sorghum that was ensiled until 10-14 days after harvesting. With many things dilution is the solution. Feeding other feeds will be effective in reducing risks. Finally, although I know of no cattle deaths due to feeding sorghum that was frozen it is possible that low levels COULD add to livestock stress if fed right after a frost.

Question I just finished combing soybeans and notice some patches of perennial sow thistle. These are clipped close to the ground. Are they worth spraying? Answer Absolutely yes. Any chance you have to spray perennial sow thistle take it. It would be nice to leave 2-3 days between combining and spraying to allow some growth and the dust to be blown off the rosettes. (In this case the patches are so small they will be spot sprayed.)

“Trust me: There is no “them”."

- Kevin Kelly