13 min read

The Cropwalker - Volume 4 Issue 18

Always read and follow label directions.

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Crop Conditions

Winter wheat is progressing nicely. Later seeded fields are at 2nd node. Earliest fields at 3rd node. Further south (Essex/Kent) earliest fields have flag leaf emerging. Corn planting as of May 2 about 29% of corn in and 5% of soybeans planted across Ontario. The past 7 days have been slow as far as planting and spraying. Most areas had temperatures at or below zero. This slowed down spraying and some growers did not plant. As of May 10-11, planting is resuming and most areas hope to be going by the weekend. We will do another planting progress this coming weekend (will be posted on Twitter Friday evening). Last year on May 10th Ontario was 68% corn planted and 14% soybeans planted. We are behind that this year but hopefully we will catch up this week. It appears as if most growers are not concerned about planting into cold soils. As one grower said about planting into cold soils “naah that was late April, now in May it is full steam ahead” Last year there was a lot of worry about cold water imbibing. Then we pulled off some great yields. I think the main thing we learned last year is that 1) some hybrids can withstand cold soils better than others. Check with your dealer about your hybrid. 2) We had a reduction in population in some fields. Consider increasing your seed drop, but check with your seed dealer to see if your hybrid yields ok with a higher seeding rate in case they all come up. Below is a summary of imbibing cold water.

Switch hybrid dates, 3200 CHU areas the switch date is May 31, for 2800—3200 CHU switch date is May 25th, for lower CHU areas switch date is May 15-20.


Errata - Spraying dicamba before corn emerges.

While we strive for perfection on what we write in the newsletter, we are human, thus the disclaimer at the start of the newsletter is that you must read the label prior to applying a given product on your field. The label is the law.

In an earlier Cropwalker I said you should never apply dicamba pre emerge to corn. That is not correct. You can apply dicamba pre emerge to corn if the corn is planted 4 cm deep. There is a precaution not to spray dicamba pre-emerge on to soils with less than 2% organic matter. The label states do not spray dicamba pre plant. The concern is that dicamba on the soil surface could get moved into the seed trench when the opener makes a cut through the soil. This cut creates a preferential path for the dicamba to move towards the seed/seedling.

Q - Why is my wheat a different colour than the neighbours, are they doing a better job than me?

Ans - In many cases it is likely the difference in variety, and not management. The exceptions would be if you had differences in nitrogen/sulphur application timing and rates, or you are having patches of manganese deficiency showing up. I went to the Ontario Cereal Trails today at Palmerston and took the photo below. It is more drastic than you can see in the photo, but there is a patch work of various green shades across the plots, all with the same treatments. Ellen Sperry, General Manager at C&M Seeds mentioned to me that the differences in wheat colour will continue into heading.

Picture 1 - OCCC Winter Wheat Trials at C&M Seeds - Palmerston

Q – I am late on my Manipulator/Moddus timing, should I still apply it when the flag leaf is out on the winter wheat?

Ans – At this point if you can access the product and still want to use a plant growth regulator on wheat, it is time to consider switching to Ethrel. Usually, you apply this at full flag leaf/swollen boot with a fungicide without much crop response, however Bayer has not tested all Ethrel/Fungicide combinations. Do not do a three-way mix of Ethrel/fungicide/herbicide. Ethrel should NOT be applied with herbicide. I made a Ethrel timing video, see below. Prior to application, please read the Ethrel label.

Figure 1 - Registered Growth Regulators on Winter Wheat
Wheat - How to Time for Growth Regulator (Ethrel)

Imbibitional Chilling Injury of Corn (University of Nebraska Newsletter letter)

When corn seeds imbibe (take up) water, cell membranes stretch, and cells expand. When a damaged cell membrane rehydrates, it may not return to its normal shape and size. This can create a "leaky" cell. Water is at its densest at about 4C, so when cold water is imbibed it may result in additional membrane damage. These ruptured membranes may occur in the cell walls and in the mitochondria. In the plant this action may disrupt the embryo/endosperm enzymatic conversion to energy, but mostly results in leakage of cell solutes and sugars. This, in turn, is likely to reduce growth rate and interfere with growth of the emerging seedling. Debate exists about what specific temperature and timing causes imbibitional chilling. However, corn plants that imbibe cold water (in the low 40s) in the first 48 hours after planting undoubtedly are affected. Planting when soil temperatures are above 10°C alleviates concerns of imbibitional chilling affecting corn emergence.

Some scientists suggest that corn will not be injured at soil temperatures as low as 4C; however, there is certainly some risk of injury from imbibitional chilling at those low temperatures. Some inbred lines (seed parents) are clearly more susceptible than others, and the seed industry has been actively eliminating the most sensitive ones from use. However, if environmental conditions are extreme, many tolerant parents may still show damage—imbibitional chilling is a physical phenomenon that can override biology and genetics. (So basically, they are saying there could be some damage.)

I asked a corn breeder from one of the main corn companies in Ontario

Pat - yield depends on emergence rate but I would say 5-10% yield loss could be typical; could be less, could be more. Corteva has a lab test to screen this type of condition and leads to the stress emergence ratings in the product catalogue. Genetics and seed source both contribute.

I asked a corn breeder from one of the main corn companies in Ontario

Pat - yield depends on emergence rate but I would say 5-10% yield loss could be typical; could be less, could be more. Corteva has a lab test to screen this type of condition and leads to the stress emergence ratings in the product catalogue. Genetics and seed source both contribute.

Q What about spraying wheat now?

Ans, you must prioritize wheat fields as to weed and disease pressure. Many early planted wheat fields, fields that had a preharvest or pre plant herbicide applied or fields that were worked before planting will not need weed control as much as they need disease control. Consider applying fungicides to these fields and do a preharvest weed control later (glyphosate or glyphosate plus Eragon). For fields with heavy weed pressure, you will have to wait. If applying herbicide, spray in the middle of the day.

Q Can I spray 2,4-D ester and work it in before I plant soybeans?

Ans From Mike Cowbrough OMAFRA Field Crop Weed Extension Specialist

I don’t like it. I rarely see bad soybean injury from 2,4-D. The one exception has been when it was applied then incorporated and then planted into.” IF you need to do this, Eragon is likely a better fit as far as crop safety.

Q I sprayed an early fungicide on my wheat, should I still spray a fungicide at flag leaf?

Ans Yes. The fungicide you already sprayed protected the leaf area that was there at the time. It will not translocate to new leaves to protect them. Current weather is wet, and warm enough for disease spread. Price of wheat also suggests do everything you can to get good yields. Most cereal fungicides applied at full rate provide control for 10-14 days on the leaves emerged at the time of application.

Q I sprayed manganese on my wheat but am still seeing manganese deficiency. How come?

Ans Manganese does not translocate in the plant. New leaf tissue will be Mn deficient. You need at least 2 applications of Mn, and maybe a third under dry conditions.

Q With colder weather what is expected payback with plant growth regulator (PGR) on wheat and which product is better under cold weather conditions

Ans For soft red wheat, on fields where lodging has never been an issue you probably will not get a payback with a PGR. The current cool weather as wheat is elongating will make wheat shorter. Of the two Moddus and Manipulator, Manipulator has shown to be less affected by cool weather.

Soybean burndowns

Canada Fleabane is absolutely loving the cool weather – peak germination temperatures have been ideal over the last month, and it just keeps coming. Fall-established rosettes are big, and upright ready to bolt with some growing weather. This changes the burndown game and betrays the weaker products that rank below 80% control in Sikkema’s research.

The Kixor products – Eragon LQ, Optill, Integrity – require actively growing weeds, good growing conditions, and lots of water for coverage and efficacy. Avoid spraying early in the morning or at dusk, and 20 GPA of water is required in these conditions and with this type of weed size. Adding an effective systemic mode of action to Kixor in the tank is a proven winner in Sikkema’s trials, and will provide tremendous agronomic value given the current growth stages of these weeds.

Xtend Soybean – add Engenia at 404 mL/acre (equivalent to 0.66 L/ac of Xtendimax)

Enlist E3 Soybean – add 2,4-D choline (Enlist) at the recommended rate.

Conventional IP Soybean – a metribuzin/Sencor product will be vital to this program as always.

(notes from Ken Currah BASF)

Picture 2 - Canada Fleabane plant with size 13 boot

Antagonism Between Metribuzin and Glyphosate

Clay based products like metribuzin (Sencor/Tricor/Boundary/Conquest, etc.) can tie up glyphosate. The table below indicates that 1.0 L/ acre of a 356 gm/L glyphosate loses some activity on perennial weeds, such as, dandelion, and perennial sow thistle. Annual weeds like mustard, and lamb’s quarters, are not affected. This antagonism is overcome by increasing the rate of glyphosate. In this research 0.25 L/ac of glyphosate (356 gm/L) were needed to overcome antagonism for perennial weed control.

Figure 2 - Glyphosate Rates and Metribuzin Tie-up

Spraying Weeds in Cool Weather

Weeds must be actively growing to be controlled. You like to have air temperature above 5C the night before and 10C the day of and after spraying. The warmer the weather the better the weed control. And most herbicides have a 1-4-hour rain free period. (check  Pub 75 or a label for specifics). HOWEVER, you will still get some weed control if the temperature is not ideal. Probably better to have reduced weed control by spraying when temperature is cooler as opposed to not controlling weeds. If you delay spraying, and weeds get bigger they are harder to kill and bigger crop easier to damage. Sunshine and heat while spraying is more critical than a cool night. After a cool night plant metabolism is slowed down. Once it warms up and the sun starts to shine plants start to grow again. Thus, if cool nights spray in the middle of the day as opposed to mornings or evenings. Watch winds. Winds can stress plants and cause off target movement. You probably saw the video of off target spray movement when being cautioned about spraying dicamba. The same type of off target movement occurs with all herbicides, resulting in uneven spray applications. I have seen this happen when a pre emerge herbicide was applied while too windy. Wait at least 24 hours after a frost before spraying post emergent (if the ground is wet the plants may not have experienced freezing conditions even if air temperature got to freezing) Surfactants either already in the herbicide or added will increase herbicide activity but can also increase crop damage.

How Long Must Glyphosate be on Before Tillage?

For perennials it is nice to have 48 hours and 24 hours for annuals. Reality is if applying glyphosate as part of a burn down probably 1-2 hours between spraying and planting will be adequate. Nice to have longer but you will get significant activity from glyphosate if it is only on for a couple of hours. The compromise is less weed control vs. getting glyphosate activity. If only a few hours, count only on top growth control of perennial weeds.

Should I be adding Metribuzin (Sencor/Tricor) to my Soybean Burndown?

If you are not using Eragon, the answer is yes. A more recent slide suggests that the spread between Eragon with and without metribuzin maybe be wider than what is listed below.

Why should I top-up the Metribuzin in Boundary when spraying Pre-Emerge?

You should consider topping up the metribuzin portion in your Boundary IF a) you do not have triazine resistance and/or b) you farm fine textured soils. By doing this you should expected improved control on non-triazine resistant weeds, such as lamb’s quarters, mustard, and common ragweed control. Also, may improve control of Lady’s Thumb, Wild Buckwheat, Cocklebur, and glyphosate resistant fleabane.  On Medium Textured Soils, using 1 L/ac of Boundary provides enough metribuzin in most instances. Higher rates may increase crop injury without additional benefit on weed control. On Fine Textured Soils, consider using 1 L/ac of Boundary plus topping up with additional Sencor.

Figure 3 - Topping up Metribuzin by Soil type (Boundary LQ)

Q I have soybean burn downs and pre-emergent corn herbicides to apply, which takes preference?

Ans It depends. Some of the issues; Bigger weeds are harder to control. If you have big fleabane to control before soybeans, they will take preference. Another part is which field has the most weeds. If you are spraying a pre-emerge herbicide on corn, you can spray those fields without worrying about hurting the crop. It is true the glyphosate may not give much control under current weather but the pre-emerge herbicide will be there to give activity. If you hold of your pre-emerge herbicide and it turns dry they will not work. If your burndown on soybeans does not work, spaying it first allows more opportunity to reapply a rescue. Controlling glyphosate resistant weeds in soybeans, like fleabane, can be much harder than in corn.

Q – Jonathan, why don’t you have Express SG on your list of burndown products?

Ans – I have had about 3 different people in the last week ask about Express SG (tribenuron-methyl, group 2 from FMC- same active also found in Refine/Barricade M), so it is time to write about it. I did miss including Express SG in my list of soybean burndown products. If your fleabane is group 2 resistant (which it’s best to assume it is), then you will not be able to control with Express SG.

So where does it fit? I like to see it used on weeds that glyphosate is weak on. This would mainly be Wild Carrot, Scentless Chamomile, and glyphosate resistant volunteer canola.

One item of note is there is a minor use registration for Express SG plus glyphosate as a pre-seed burndown prior to seeding alfalfa (both seed and forage), red clover or alsike clover. Planting for those crops can start 24 hours following application. The same registration also applied to Smooth Bromegrass, Meadow Bromegrass, Timothy and Creeping Red Fescue. I mention this in case you want to “plant green” with no-till alfalfa into a fall established forage, and not use glyphosate.

Please observe soil type restrictions listed on the label.

Tank Mixing Herbicides

Figure 4 - WALES

Herbicide Mixing Order WAMLEGS (includes microencapsulated products like Prowl)

Figure 5 - WAMLEGS

Soybean Planting and Temperature

Research in Manitoba and Ontario suggests that once the risk of frost has passed (when soybeans would emerge), planting date plays a bigger role in final soybean yield than soil temperature at planting, especially if soils are fit (which most are today). The number one deciding factor on whether you will have success in cold soils, or not, is seed quality. Soybeans emerge within 24-35 days when seeded into 6-12 C soils, and 4-16 days when seeded into 14-22 C soils (based upon soil temperatures at 2”, for two consecutive days) (Manitoba Pulse and Soybean Association data).

Spreader Misapplication

If you are using a spreader, and it was not calibrated for the product being spread, expect to have an uneven spread pattern. Prior to GPS we use to blame spreader performance on the guy’s driving habits. Once everyone could drive straight every 40, 50 or 60’, then it was fairly obvious the machine just wasn’t quite dialed in. When they are calibrated for the product being spread, it is quite impressive how accurate the spreader can be. In Europe, they calibrate the spreader for each load of fertilizer (if quality changes). This does not necessarily mean doing a pan test, but it does mean checking bulk density and the SGN size and adjusting accordingly.

Q. Will it pay to spray Priaxor on alfalfa?

Ans One grower said he needs about 300 lbs/ac of additional alfalfa to make Priaxor pay. On 2 and 3-year-old stands you should expect 10-20% yield increase. So, if your normal first cut yields are 2 tons/ac (4,000 lbs/ac) a 10-20% yield increase equates to 400-800 lbs/ac plus an increase in feed value because of leaf retention. There is typically an additional yield response in the following cuts as well.

Common Mallow – Weed ID with Brittney Littlefield, Fieldwalker Agronomy Intern

In its early stages, Common Mallow can be mistaken as Velvetleaf. Both weeds are in the Malvaceae (Mallow) family, showing similarly rounded and slightly toothed leaves as a seedling. However, differences between common mallow and Velvetleaf are seen in the smoothness and definition of the leaves. At the early stages of development, Common Mallow will keep a more upright shape. At the same time, Velvetleaf will have more of a drooping look. As well, Common Mallow shows smooth leaves while Velvetleaf has a hairier and more fragile look. Later, at the mature stage, Common Mallow is easily identifiable by its purple flowers and Velvetleaf with yellow flowers, erect stem, and very large soft leaves.

Picture 3 - Common Mallow (Brittney Littlefield)

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