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The Cropwalker - Volume 2 Issue 27

Always read and follow label directions.

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Crop Conditions

Crop conditions - Winter wheat – harvest has started in Essex. Only news is that wheat is grade #2 and no fusarium. As one agronomist in that area said, “there is not a lot of wheat acres here, and of those few, some are not ready”. Hot dry weather has stopped secondary spread of any fusarium. Expect dry conditions in other parts of the province will speed harvest. If you are using Roundup pre harvest, remember it is for weed control, not desiccation. If you want to desiccate wheat and weeds you need something like Eragon. Eragon will desiccate broad leaf weeds but not grasses. Corn – some fields are really struggling due to lack of soil moisture. There are numerous deficiencies showing up. Most typical are nitrogen and or sulphur. In the first case it may just be a case of roots not being able to source applied nitrogen. With S, it is usually a case of S not being applied. Magnesium deficiency is showing up in fields with low Mg levels. For Mg deficiency consider applying foliar Magnesium sulphate. Soybeans – earliest fields are flowering. Most fields are just sitting still waiting for some rain. One agronomist has reported seeing quite a few aphids in hort crops, so continue to scout for this pest. – Forages - Progressive producers are harvesting second cut. Fields that received rain last week have higher yields than first cut. Lower yields where no rain. Direct seedings are harvested or in the process of being harvested. Really watch for leaf hoppers if you want a cut in 4 weeks. Spring cereals -earliest fields are heading. Minor cereal leaf beetle showing up in some fields.


Slowing down red clover in winter wheat with Eragon

If your red clover is getting too high for good wheat harvesting, consider using Eragon. Eragon is registered from 30-60 ml/ac as a preharvest desiccant in winter wheat. According to BASF Eragon at 45 ml/ac along with Merge at 400 ml/ac has historically given a good “slow down” effect to red clover. This treatment sets the red clover back enough to allow you to harvest the wheat and then the red clover should grow back. You can feed straw that has been treated with Eragon. One option is to spray Eragon plus Merge, combine the wheat and then go in with a disc bind to cut the rest of the wheat straw and red clover, for baling. If you want the red clover to survive, do not add glyphosate to the Eragon.

Current weather is conducive to hail

When you have hot humid weather there is a good probability some place there will be hail. Not much you can do. Corn that has not tasseled and is damaged with hail will grow back. There is some on-farm-experience that spraying with a fungicide as soon as possible after the hail event will reduce the amount of disease that attacks the bruised corn plants. To do this you will have to have fungicide on hand. I have not seen or heard of any such activity in a soybean field.

Barnyard grass misses

There are a number of fields sprayed with glyphosate in S Ontario where barnyard grass did not die. Dr. Peter Sikkema believes that all were sprayed late because of wet weather. The barnyard grass was bigger than normal. All fields had metribuzin or dicamba in the tank mix. Both herbicides can tie up glyphosate. Resprays will tell us more.

Spraying corn for DON reduction

If you are a dairy producer consider spraying your silage and grain corn with a fusarium controlling product. This year’s strategy is to use a product that has both a strobilurin and triazole. This will control DON and leaf diseases Research from BASF has shown a 50% reduction in the amount of fusarium found in corn that was sprayed with a fungicide. In speaking with one supplier rep, their experience has been that fungicides registered for DON reduction in corn may have a similar yield response to those used for plant health. Eventually I would expect more growers will spray for DON reduction in corn, similar to winter wheat, than for just the yield benefit. Primarily to ensure they have a marketable product.

Fungicide on Silage

One of our reader’s uses a fungicide on corn silage, to reduce the rapid drop in plant moisture at harvest. He feels that fields sprayed with a fungicide have healthy leaves that stay green longer, and, you do not experience that sudden drop in silage moisture content. For Silage, use a fungicide that controls DON and stalk rots, as the vomitoxin can be in both the stalk and grain. Fungicide on the crop is substantially cheaper than using a feed binder in the ration but may still be required depending on the situation. The vomitoxin can be in the stalk, as well as the grain.

Considerations for spraying a fungicide on grain and silage corn

Fungicides on corn can increase yield and reduce DON. There is a chance that you may be in a crop insurance situation because of low yield. However, I think having low yield and corn with high DON would not be good. If there is a low corn yield you want to have the highest quality possible for sale. In the traditional high DON areas consider spraying for DON reduction. (If someone has another point of view let us know so we can discuss.) To me the preferred application system is with ground equipment. Silage from what I have seen every dairy farmer should be spraying corn silage with a fungicide. If you have limited dollars to spray corn and soybeans suggest you spray corn first. You should use a product that has more than one class. Use a product that has a strobilurin and a triazole. Syngenta are promoting Trivapro since it has excellent activity on several corn leaf diseases. They also have a limited amount of Miravis Neo this year (new fungicide) which is strong on NLCB and other foliar diseases. It is also effective on ear moulds, the plan is to target the ear mould market this year with the limited supply (try a side by side, not whole farms). BASF are promoting Headline AMP + Caramba, to get both the leaf disease protection and plant health benefits from the Headline AMP, and then the DON protection from Caramba. If someone isn’t so concerned about one or the other and cost or weather becomes a larger concern, it’s easy to then take a product out of the mix. Also, no aerial permit required for Headline AMP or Caramba. Priaxor is a great option for leaf diseases but does require an aerial permit. Bayer has been promoting Proline for DON reduction, or Stratego Pro + Proline for those looking for both plant health and a DON reduction.

Corn Fungicides – What diseases to target?

Frequently around this time of year, the question is what product should I use at tasseling? The question back is, what yield robbing diseases are you targeting? Luckily, the Crop Protection Network has a database on the main yield robbing diseases in corn. See the table below. However, you also need to consider total revenue, as discounts due to high DON levels is not accounted for.

Table 1 - Main Yield Losses in Corn due to Disease

Soybean Fungicides – What diseases to target?

Like the corn question above, target the main yield robbing diseases. For root rots and stem diseases like sudden death and soybean cyst, make note for future years, so that variety selection and/or the seed treatment can be adjusted. In Ontario, the largest yield robber that can be controlled in-season is white mould.

Table 2 - Main Yield Losses in Ontario soybeans due to Disease

Volunteer Corn Herbicides/Fungicides in Soybeans

Can I mix my volunteer corn herbicide with my fungicide? Yes, although you may be on the late side for controlling volunteer corn. Watch your surfactant load with this mix.

Insect Watch

Potato leaf hopper in alfalfa are yield reducers. Alfalfa cut in early July is the crop most at risk. Check fields and if you see significant numbers spray dimethoate (Cygon/Lagon)). Matador is also registered but it breaks down quickly in hot weather. Potato leaf hoppers are wedge shaped, light green in colour. The larva (nymphs) feed on the underside of leaves. They can be identified by their movement. They can move forward, backwards and sideways with equal speed. They are blown in each year from the US Gulf area. They start to build up around July 1. Leafhoppers go through 2-4 life cycles a season in Ontario. Heat encourages shorter life cycles and higher leafhopper levels. Females lay 2-3 eggs daily in the stems of alfalfa plants and in the main veins and petioles of bean leaves. Eggs hatch about 9 days later. Just cut Alfalfa in early July is the crop most at risk. Check fields and if you see significant numbers, spray dimethoate (Cygon/Lagon)). Females live for about 1 month. Spraying dimethoate gives some initial knock down. I figure about 30% of dimethoate activity is by knock down. The other 70% is by residual. The plant takes up dimethoate. Dimethoate does not kill the eggs. Any eggs that hatch or leafhoppers that fly in will be controlled by residual dimethoate. The residual should last for about 10 days. Matador is not systemic. Matador residual is shorter than dimethoate and Matador breaks down quicker when it is hot (over 25 C)

Not to spray for leaf hoppers in new seedings must be a conscious decision. They can also be very damaging to edible beans especially under hot dry conditions.

Soybean aphids (SA) No reports of buildup. Current weather is conducive to SA activity. There is an app to help with decision to spray. Go to http://www.aphidapp.com/ to download the app for free. Japanese beetles may also become an issue as populations are abundant this year. Western Bean Cutworm Monitoring in Ohio for the past 2 weeks show a very low number of adults in the traps this year to date.  Cereal leaf beetle (CLB)– some limited feeding of what must be a late batch. Typically, CLB have one generation a year. Often adult feeding can be seen in spring grain or corn. These are adults that have hatched from this year’s eggs and will over winter as adults. Thrips - in corn, have been seeing limited feeding on corn leaves, especially on fields that had manure. Based upon one retailer’s side by sides in 2018, you need fairly high levels to cause economic damage, when controlled at the 10-12 leaf-over stage.

Picture 1 - Thrip Feeding in Corn

Straw Value

I am always reluctant to give a price/value on straw. Using P&K values of $0.70/lb. of P and $0.45/lb. K the nutrient value in straw is about 1 cent/lb. There is a variation since the P&K levels in straw varies. Ag newsletters in the US suggest a much lower level of P&K in wheat straw. The organic matter value of straw is minimal. The real organic matter value in wheat is in the roots. SELL STRAW – BUY FERTILIZER.

How Do Cool Nights Affect CHUs?

Corn produces carbohydrates during the day and translocate them during the night. Corn likes hot days. Maximum corn growth occurs when maximum daytime temperature is between 17°C and 33°C. Corn growth is also affected by minimum temperature. Maximum growth occurs as long as the minimum temperature is above 24°C. For example, if the maximum temperature is between 27°C and 33°C and the minimum temperature is 24°C you collect 34 CHUs. If the minimum temperatures drop to 14°C you get 25 CHUs. That is about 25% less. If the temperature drops to 9°C you only get 20 CHUs. Typically for July the average maximum temperature is 26°C and average minimum temperature is 15°C. This equates to 26 CHUs daily.

Table 3 - Corn Heat unit Accumulation at Various Nighttime Temperatures

Precision Ag for Forages

Forages have been treated like the red-headed step kid when it comes to precision ag, but there is hope. NDVI images use a formula based on light bands to build map based upon biomass. Since NDVI is an index, not an absolute value, total harvested weight from the field is required to provide a field map of value. Why do this for management purposes? It can provide a yield map for a crop that normally doesn’t have one, you could use it for crop removal recommendations when making fertility decisions, perhaps you have a variety trial, and lastly, field scouting to determine why certain areas of the field are poorer than others (which tends to follow topography).

I need a soybean reproductive staging guide. Do you have a good example or source?

Your out in the field and need to double check what the difference is between R1 (first flower) or R2 (full flower), or perhaps, what R3 or R4 mean when it comes to developing pods. The one below is a couple of the best I have found. Have something better? Please share.

K-State Soybean Growth Stage Guide

One Page Guide on Soybean Growth Stages

Cool Bean Soybean Growth Stage Guide

Intensive Guide on Soybean Development

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