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The Cropwalker - Volume 3 Issue 23

Always read and follow label directions.

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Crop Conditions

Winter wheat  Earliest fields in Essex Kent have lost their “greenish tinge”. This suggest harvest will start first week of July. FHB spraying is done except for later planted fields. Armyworm are alive and some spraying occurring. Keep watching. Corn From 5 leaf to will close canopy his week. Many fields are too late for weed control. Soybeans also look very good. Weed control has been pretty good. Some fields with ragweed escapes. Seems to be more grass escaped this year than most years. It is easier to control grasses in soybeans than to control broadleaf weeds. As we approach the summer solstice it is time to think about white mould. R1 will be approaching quickly. Forages first cut was OK. Not great. But good soil moisture means second cut should be good. There were/are alfalfa weevil but cutting is the best control method. If spraying Priaxor best results are 21 days before cutting. Potato leaf hoppers are starting to be at threshold levels in eastern Ontario where conditions have been dry. Pastures alive and well. Perennial weeds are growing well. Cannot spray herbicides if legumes in the mix. Best bet is to clip short as possible and fertilize.


This week is critical for weed control. Stage of corn and soybeans is critical. Some of the suggestions below may be too late for some acres. In general, annual weed control is pretty good. But there are a lot of patches of perennial weeds. If spraying dicamba check BASF web site for risk of volatilization. https://www.engeniaspraytool.ca/

Perennial Sow thistle

How much can Perennial Sow-Thistle reduce yields? In corn, 4% at 1 plant per meter squared, 15% at 5 plants per meter squared. Soybeans 5% at 1 plant per meter squared, 20% at 5 plants per meter squared. This is under the assumption plants are not controlled in season. This weed is easy to kill or suppress. It is a perennial, so you need to control it at least 3 times. Most growers spray it two times and figure it is gone. But it is not. You have to be serious about controlling it. In Roundup Ready soybeans use 2x rate of glyphosate (I had great success with this last year)

Best Herbicides for Perennial Sow-Thistle in Conventional Corn following are the top-rated options.

Marksman – 90% @ 1.5 L/ac, Distinct – 80 % @ 115 gr/ac; low rate dicamba – 80%; Peak 80%.

For conventional soybeans, the top-rated options are.

Clean Sweep, Basagran Forte, Blazer or Classic all provide similar level of top growth control at 70%. Best option is glyphosate pre-harvest, to reduce populations long-term.

Alternatively, if you have a roundup-ready crop planted; glyphosate @ 1 REL/acre is the best value for the control – 75%. The 2x rate provides 85% control. Round-up – Ready corn -> Lontrel + glyphosate – 90% (watch rates for recropping).

Problem weeds in corn

Following is some suggestions. There are a lot of options for all these weeds. Talk to your dealer and they may have another option.

Horsetail – Broadstrike does a better job than any other product. You can use Broadstrike on emerged corn up to 8 leaf. Will tank mix with glyphosate. You cannot use Broadstrike on emerged soybeans. I have seen good success in burning horsetail off in soybeans, in-crop with either Reflex or Flexstar (pre-mixed Reflex (encapsulated) + glyphosate). Do no make your own Flexstar. You can top up the glyphosate rate in Flexstar.

Glyphosate Resistant Fleabane in corn.

Acuron up to 6 leaf, Marksman up to 5 leaf, Distinct up to 6 leaf, (do not mix with glyphosate), Engenia/Xtendimax up to 5 leaf, Pardner + Atrazine 4-8 leaf. Lontrel up to 8 leaf.

Tufted Vetch – Distinct or Callisto in conventional corn has been proven to be the most effective. Callisto, or Dicamba can be tank-mixed with glyphosate in Roundup Ready. Late post is ideal for maximum kill, will require a two-pass approach to avoid significant yield loss. New kid on the block to try is Lontrel. Watch rates for recropping purposes.

Can I Tank Mix Volunteer Corn Products with Clean Sweep?

Although not registered, it is safe to mix Assure II or Venture L with Clean Sweep. However, at Clean Sweep timing some of the corn may not have germinated. You may have to spray a second time for later flushes. If using Assure II, you must keep the rate at 150 ml/ac. You would consider adding Assure or Venture if the grasses are beyond the Cleansweep label.

Controlling Volunteer Corn in glyphosate tolerant Soybeans

It’s my understanding that several grass control products in soybeans have been repriced for 2020. As a result, it is much cheaper than in the past to control volunteer corn. If you must spray for weeds, and already have volunteer corn up, add the graminicide to your glyphosate on the first pass. If you have to come back a second time, so be it. Only time I would wait is if volunteer corn was the only weed in the field. This is the opposite of what we use to recommend in the past, which was wait for everything to be up, and then spray, just prior to canopy closure.

Ragweed Control in IP Soybeans

If ragweed got by your pre emerge product there are some choices. Basagran, Reflex, Classic (if not 2 group resistant, almost all areas growing soybeans are likely to have group 2 resistance), will control smaller ragweed (2-6 lf) Blazer will control ragweed up to 8 leaf. I have found the lower rate of Blazer with surfactant can be more effective than the full rate. You will have more burn with surfactant. High water volumes are a must regardless of product.

Spraying Reflex, Pinnacle and Classic on Hot Days

Reflex is safer on white and black beans than on soybeans. If spraying soybeans you cannot reduce the surfactant rate and maintain weed control. On hot days with bright sunlight (27-28 C and up), it is best to wait until 5:00 p.m. before spraying. If you can wait until later in the evening, even better (weed control may suffer with group 14 herbicides, like Blazer and Reflex). You want the plant to be able to break down the herbicide in the first few hours after application. The same is true with Classic and Pinnacle. Do not apply full rate Classic and Pinnacle in a tank mix. These three products can all damage beans. You have to decide if the weeds will hurt yield more than the damage the herbicide will cause. There are a lot of other tank mix do’s and don’ts. Check with your dealer. The hottest tank mixes are combinations of Reflex and Classic +/- grass herbicide or Reflex and Pinnacle +/- grass herbicide. I would rather injury the beans and control the weeds than see weed escapes.

Getting the Most from Reflex

Notes from Brian Woolley with Syngenta. Count on spraying Reflex for ragweed 20-21 days after planting. To get the most from Reflex on hot days when the weeds have “hardened off” you must do certain things. 1) Use flat fan nozzles not AIs. 2) Use 20-25 gallons of water. 3) Use the high rate of Turbo Charge (or similar surfactant) at 5L/1000 L water. 4) Add 1.0 L/ac 28%. 5) Spray before 9 P.M.

The common factor of Blazer, Liberty and Reflex

All three require sunlight to kill the weed. Think about Eragon. You get the best burndown or pre-harvest control when you spray it during the middle of the day. Eragon is in the same herbicide group as Reflex and Blazer. We typically don’t recommend that these be applied in the middle of the day due to crop injury, but it would provide the best weed control.

Adding Non-Ionic Surfactant (NIS) to Soybean Herbicides

The amount of surfactant you add is an art. The surfactant helps to cut through the cuticle of broadleaf weeds. Weeds like ragweed and velvetleaf form a thick cuticle under hot, dry conditions. The hotter and drier the conditions are, the thicker the cuticle. Some products need a 0.2% NIS v/v. As weeds get bigger and tougher it is common to increase the rate up to 0.3% and even 0.5% v/v. The addition of 28% can make these products even hotter. For instance, adding 28% often helps to control velvetleaf and lamb’s-quarters. With many of the broadleaf products, spraying in the heat of the day gives the best kill but also burns soybean leaves more. A compromise is to spray mid- to late afternoon and evening. This gives the benefit of burning the cuticle of the weeds but allows the soybean plant to break down the herbicide in the cooler part of the day. Generally, broadleaf products are harder on soybeans than grass products. There is a table on pg. 88 of the 2020 Pub 75 to convert rates of NIS to L/100 US gals, or you can use the one below.

Adjuvant Volume/Volume Chart

Whenever I don’t have this chart at my side during post-emerge spray season, I’m not long looking for it. Here’s a copy for you as well.

Figure 1 - Surfactant Chart

Metribuzin (Sencor/Tricor/Squadron) Effect on Soybeans

I refer to it as “affect” since often there is no yield loss associated with it. The affect occurs in two ways. 1) Metribuzin can be splashed onto the leaves of the beans. Typically, this is only on the unifoliate but can sometimes be on the first trifoliate. Metribuzin is splashed onto the leaves from rain after application. 2) The other way is root uptake. This shows as browning and chlorosis around the leave edges. Metribuzin is translocated to the leaf edges where it damages. This occurs because of root uptake. Conditions that favour this are, light sandy soils, shallow planting, high rate such as overlap. This type of affect is more serious and can cause a yield loss. The image  showing metribuzin symptoms.

Picture 1 - Boundary/Broadstrike showing Metribuzin symptoms

Spraying glyphosate on corn. Label states you can spray up to the 8-leaf stage. After that stage it is hard to get good coverage. You can spray glyphosate under hotter conditions without affecting corn than most other products. You have to be concerned about off target movement with glyphosate the same as with other products. Part of the issue with spraying glyphosate past the labeled stage is if one of the corn hybrid parent’s didn’t have the Roundup ready gene (usually the male), there is a portion of the kernels that will abort once the cob starts to form. 25% of the embryo’s will not have the trait, and glyphosate remains in the active form, being translocated out through the roots or into sink tissue (kernels).

White Mould Control in Soybeans

We have asked BASF, Bayer, and Corteva for their best white mould strategy

Here is the suggested BASF strategy.

Figure 2 - BASF White Mould Strategy

Corteva strategy

We need to use Acapela as a preventative application at R1 (beginning bloom). Followed with 2nd application 7–10 days later at R2 (full) bloom). Rate is 0.35 L/ac each time. Minimum of 10 gallons of water. NO SURFACTANT required.

Next week we will have Bayer’s strategy, along with a few proper staging charts.

Ungerminated corn seed

The picture below was more common this year than most. The roots (radicle) started to grow but the shoot did not. When a germination test is done these types are classified as “ungerminated”. They are very common. You could expect 1% or 1 in 100. That would give you 1 to 3/1000 of an acre population checks.

Picture 2 - Ungerminated corn seed

Fertilizing pastures Most important nutrient is nitrogen. It is nice to have at least 50 lbs of N 20 of P and 50 of K If half of the N comes from ammonium sulphate you have enough S.

Spraying fungicides on spring cereals.

If you want oats and barley to yield, and to pay you must spray for at flag leaf or heading for leaf diseases. Fusarium is usually not an issue with barley, and oats as current varieties are not susceptible (flower in the boot) but leaf diseases are yield robbers. Spray a fungicide once the flag leaf emerges, which is now in many fields. This has a fairly wide window, (emergence to heading).  This will increase grain and straw yield. The straw should also be better quality, having less dust.

Proof of Concept Trials

Running several proof of concept trials on field scale acres. The goal is to see if management practices other growers are trying can be executed on, and what some of the potential upsides/downsides are for these. In no particular order.

Planting Soybeans “Green”

Biggest issue I see with this practice is that if you have been growing non-GMO or IP varieties, and you MUST get the pre-emerge/burndown done in very short order. This year the beans were cracking through the soil in 4 days. So, if you decide to try and grow non-gmo genetics, have the sprayer follow the drill or planter. I have had my share of non-gmo fields miss pre-emerge and/or burndown, and it is hard on the pocketbook and ego for everyone involved. This practice did provide excellent soil tilth and had no issues with soil crusting. Soybeans were drilled in 2” deep. This field was winter wheat, no-tilled Oats, grazed, left over winter, had volunteer winter wheat in spring. See spray miss for density of wheat volunteers.

Picture 3 - Late April Burndown Check - Volunteer Wheat and Minimal Weeds
Picture 4 - Spray miss - Volunteer Wheat Density
Picture 5 - Strong emergence and excellent weed control

Strip-tilling and Planting Corn “Green” into Hay

This was a small area that was a last-minute addition and did not get burned off in the fall. Given the size, and the fact it isn’t tiled, it was appropriate to try strip-tilling into it green. The custom operator did have to go over the field twice to make a seed bed and was not quite as good of a seed bed as those fields that had a fall burndown or were being spring stripped into soybean stubble. Compared to the no-till check in this field, there were quite a few more volunteer alfalfa escapes within the corn row. Herbicide program may require some tweaking if this is tried again in the future. Equipment floated on the field really well, which was one of the reasons it was left.

Picture 6 - Stripped green, planted, prior to spraying
Picture 7 - Stripped green, post spraying, corn at 5 leaf over
Picture 8 - No-till corn on left, strip till corn on right
Picture 9 - Growth stage difference

No-tilling and Planting Corn “Green”

Took awhile for the plants to come up, but once they did, I was impressed with the stands, I did notice that this area is about 1 leaf behind the strip-till area beside it, it is also several inches taller. I felt the weed control was excellent and was impressed with how little disturbance occurred after planted. Would try this again, biggest challenge I foresee is how to get the fertility on, especially on lower testing farms like this one.

Picture 10 - No-till corn, planted green, prior to spraying
Picture 11 - No-till corn, 4 leaf over, excellent weed control

No-tilling Soybeans into Alfalfa/Forages

This field had a fall burndown and was originated slated to go to strip-till corn, due to lack of tile corn was moved to a farm with better drainage. What impressed me was how easily the seed trench opened and was able to place seed into moisture. Excellent tilth. What I was slightly disappointed later when the reduction in populations after having to double up on the field (15” rows with a 30” planter). The amount of compaction and reduction in stand from that one extra pass was much more than I had expected. In the future I would swing the draw bar from side to side to avoid having to drive on-top of the row when doubling back. In hindsight, the soil structure that was there carried the planter extremely well, in a situation that otherwise would not have occurred with conventional tillage. Was dry enough to run the planter, but too wet to drive on top of the row. Also, the volunteer alfalfa regrowth, even with a fall burndown was more than expected. Need to get those applied earlier in the fall.

Picture 12 - No-tilling soybeans into sod
Picture 13 - No-tilled soybeans into sod, 2 trips with planter

"Inversion: Sometimes you can get to a good outcome by avoiding bad outcomes"

- Shane Parrish