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The Cropwalker - Volume 2 Issue 26

Always read and follow label directions.

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Crop Conditions

Winter wheat – really turning as the heat has showed up. Should be 6 weeks from FHB spraying to harvest. Suggest you get ready to harvest wet. Don’t wait to see if you can field dry it. Start at 18% or when ever you can combine it. Prepare to air dry or take to elevator. It appears that rain-dry weather will continue. This type of weather allows fusarium to grow, on the head. There is confusion between fusarium head blight and take all. Fusarium can be anywhere on the head. If it is on the tip that is not as bad as if it is on center part of head. Fusarium will spread on the head with wet weather conditions. Thus, the urgency to get it off as quickly as possible. Wheat guru Phil Needham taught us that “nothing good happens to wheat under 30% moisture.” If using Roundup pre-harvest, check the peduncles. That is the part of the head where the head attaches to the stem. When 90% of them are brownish the wheat should be at 30% moisture and ready for pre-harvest Roundup. Corn in many fields is knee to waist high, and growing rapidly trying to catch up. Typically, if corn tassels in July it will make a good crop. Soybeans – haven’t heard of any flowering but they should be by the time you read this. Weather last week should have been too hot to allow aphid build up but keep a close eye.  Forages – while some are still struggling with first cut, second cut should be ready this week. Summer is when alfalfa starts to show boron deficiency. If you are pushing alfalfa, consider broadcasting 1-pound actual boron after second cut. Spring grain – if you have not applied a fungicide for rust control in oats and other leaf diseases in barley and spring wheat now is the time to do it. Products of choice are Folicur or Caramba or Prosaro. This should be applied if grain is for forage or being kept for grain.


Fusarium in Wheat

Fusarium will start on any kernel on the head. Wheat opens its flowers at pollination time. Fusarium can infect whatever flower is open when the spores are in the air. The initial infection is not bad. If weather stays dry the infected kernels will not develop, and the seed and will be blown out the back. It is the secondary infection that causes problems. If the weather stays wet the infection can spread to other kernels. If these kernels are well developed when the disease spreads, they will be too heavy to blow out. The key is to harvest wheat as soon as possible. Once it drops to a moisture level that you can get it into the bin, start. This is not a year to delay harvest hoping to avoid drying costs. There are Fusarium look alikes. The main one is take-all. Take-all presents as all or big sections of the head having no kernels. Right now, the head will appear light in colour or grey.

Picture 1 - Take-all in Winter Wheat
Picture 2 - Thumb on peduncle; Fusarium infection

Colours in the Corn Field

You may have seen some plants with inter venial light green colour. This is hybrid specific. Some hybrids produce chlorophyll slower interveinal than others do. The bottom line is it is not yield affecting and, in a while, you will not see it. The other colour you may see is sun burnt leaves. Typically, when there is a period of rapid growth and bright sunlight the tissue gets a “sun burn” This does not affect yield and soon you won’t be able to see it either.

Picture 3 - Intervenial striping on corn
Picture 4 - Sunburn on Corn Leaves

Horsetail Control in Soybeans

One grower told me about a field where Broadstrike preplant “vaporized” the horsetail. Another grower said Broadstrike really burn it off but it is coming back. In IP soybeans Reflex with slow it down a bit. There is some research to show that Roundup at the highest possible rate will have some affect on horsetail in Roundup Ready soybeans. You have to make a resolution now that in 2020 you will put together a plan to treat all fields with horsetail. If you don’t it will just keep getting worse.

Soybean Cupping (not dicamba)

Every year we go through a period when we get calls about “soybean cupping.” This leaf cupping is occurring all over the northern and Midwest U.S. There are obvious causes such as herbicide drift or sprayer contamination. Once herbicide application is ruled out there is a consensus as to the cause. The belief is the soybean plants are expressing a physiological response to adverse growing conditions. Typically, this occurs when the soybean plant has a spurt of growth which suddenly stops. One of the reasons for this is a dramatic change in the weather. The other reason can be the application of a registered herbicide with a registered additive. There is just enough jolt to the plant’s system that it temporarily stops growing. The buildup of growth hormones (auxins) in the plant displays as if the plants received an application of a hormone herbicide. Experts agree that the exact cause is not known but the yield loss is negligible.

Can I use Proline for Rust Control?

While Proline is registered for crown rust in oats, you will be much happier using Folicur. Proline replaced Folicur in the fusarium head blight market, but then Prosaro (Proline + Folicur) was brought out, partially because Folicur provides more consistent control of rusts.

Basics of Weed Control 1.0

Want to maximize your herbicide dollars? There are a few fundamentals to weed control every crop person should know. 1) Perennials have the best kill when they are in full flower. This is due to plant sugars translocating back into the root system. During the vegetative period, plant sugars are moving out of the root system, making it difficult to get herbicide into the root. 2) Post-emerge herbicides are rescue treatments, depending on the timing and the crop, the yield damage may already be done when you apply herbicides post emerge. 3) It is more crop safe, and less expensive to take out the opposite type of weed. Prior to Roundup, it was easy to kill annual grasses in soybeans, and annual broadleaves in corn, but it is difficult and much more expensive to do the opposite.

Basics of Weed Control 2.0

To get the best return per application, most should at a minimum be doing a fall burndown to get the perennial weeds, and a pre-emerge herbicide application on their corn and soybean acres. Applying pre-emerge might not always be practical, but those two timings will provide the most consistent returns of all crop protection applications.

Yellow Canada Fleabane

If you have applied glyphosate to a field, and that field had Canada Fleabane present, and after 10 days it looks like those in the attached pictures, you likely have glyphosate resistance. Treat all Canada Fleabane as if it is glyphosate resistant. All other weeds in this particular field were showing glyphosate injury.

Picture 5 - Patch of Canada Fleabane with yellowing, all other weeds dead and crispy.
Picture 6 - Surviving Canada Fleabane plant with size 13 sandal.

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