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The Cropwalker - Volume 3 Issue 25

Always read and follow label directions.

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Crop Conditions

This week is Bugs and Manganese and Sulphur

Weather mainly hot and dry. Some areas that were really wet before are dry now. There are pockets where moisture is good. Winter wheat - Folks in Essex think harvest might start next week. Much of the wheat is filling under moisture stress. This will affect yields. Further east in Nova Scotia and PEI they are experiencing their worst drought since 1965. They will have a straw shortage. Corn - is growing without issues that are occurring in cereals and beans. There are lots of fields with rapid growth. Interveinal area is lighter green and looks like Mg deficiency. It is not. The leaves are growing so fast the plant is not making enough chlorophyll to make all the leaf green.  Soybeans Early planted are at R 1.5. Now is the time to decide if you will spray for mould. Soybean aphids are starting to show at low levels. Keep watching any area where they are found. Threshold is 250 per plant and building. Forages – potato leaf hoppers are at high enough levels to warrant spraying in many fields. Fields most at risk are new seedings seeded without a cover crop. The pre-harvest interval (PHI) varies with products. Read the label. But there are labels that read spray 48 hours before harvesting (Do not graze or harvest for forage within 2 days after application) If your direct seeding is 2 weeks from cutting and you have significant leaf hopper numbers seriously consider spraying.


Insects hot weather favours insects. There have been a few fields across the province sprayed for army worms. Threshold is 4-5 per square foot. Once they get over 1” long they are hard to control. They grow to be about 1.5” long. It is quite common to see them in areas of a field but not the whole field. Before you spray check to be sure they are through the whole field. Once wheat starts to turn, they will head for spring cereals or corn. The threshold is 4-5 per square foot. You may be able to just spray the perimeter of these fields when they start to move. When you are scouting in the middle of the day check the ground for their “frass”. In the middle of the day they will be hiding in cracks in the ground. Dig around until you find them to see how big they are. If they are parasitized, you will see little cotton balls on their back.

Picture 1 - Armyworm feeding on corn leaf
Picture 2 - Armyworm feeding on Wheat leaf
Picture 3 - Armyworm on bare soil (centre)
Picture 4 - Armyworm cleaned off crop in patches

The Life of a Leafhopper – Leafhoppers are blown in every year from the U.S. Typically, 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 main veins and petioles of plant leaves. Females live for about 1 month. Edible bean seed treated with an insecticide should give about 1 month of control. 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 residue 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.

Bean Leaf Beetle first generation feeding is evident. Joanna Wallace with Syngenta says it is worse where no insecticide seed treatment was used. The second generation is the one that does most damage.

Picture 5 - Bean leaf beetle feeding

Manganese deficiency is showing up and will continue to show. Manganese is taken up as the element manganese. If there is air in the soil manganese ion forms manganese oxide which is unavailable to the plant. If there is no air in the soil either due to rain or compaction the microbes will take oxygen from manganese oxide to form manganese ion which the plant will use. Often in a manganese deficient tiled filed the area over the tiles will be green. This is because the roots there have gone deep enough to be in soil where there is available manganese. Last week we gave you a list of products to apply. Caution if you have visible manganese deficiency you must use at least two applications. One is never enough when there are visible symptoms, as foliar applied manganese does not move to new growth Visible symptoms include darker veins and lighter green between the veins.

Sulphur deficiency continues to show. Picture shows rows that did not get S. It is not too late to apply S to corn. Because of wide-spread deficiency showing up if your corn looks a little light green, get sulphur on ASAP.

Picture 6 - Sulphur Deficiency in Corn
Picture 7 - Rapid Growth in Corn

White mould in soybeans - Why are we writing about white mould when right now it is so dry. Because there will be some fields develop mould. Last week we suggested you rate your fields for mould potential and spray ones with highest probability. To control mould you must protect the flowers. The blossoms are a source of concentrated nutrients that are a perfect place for mould spores to start growing. You need to spray the first spray at R1-1.5. That is when you see a flower anywhere on the plant. For years I was frustrated because growers would call end of July to first of August worried about the white mould that was developing. It became so frustrating for me that I started to take my holidays the last week of July and the first week of August. By the time I was back it was way too late. Even though weather is hot and dry now I believe there is enough moisture in dews and fogs to initiate mould. In fact, at one time farmers told me that is was fog that was causing mould. They were right. Some of the mould fungicides also have some control of other diseases.

Can I just increase Nitrogen the rate?

I have heard it multiple times, why don’t I just increase the rate to make up for my N losses, instead of using a nitrogen inhibitor like Agrotain Advanced? Using Agrotain Advanced is about $0.10/lb. N, to protect Urea or the Urea portion of 28% UAN. If you have purchased nitrogen for $0.50/lb. N, you could theoretically increase your Urea rate by 20%, and still have the same amount cost as adding Agrotain. But it does not work that way. Now you have doubled down at the blackjack table with a losing hand. If you are under conditions that increase the risk of volatilization, you are now losing a larger amount, rather than protecting the original rate. See the chart below, assuming the grower was going to top-dress with 60 units of N. At these price points, if you expect to lose more than 15% of N, use a nitrogen inhibitor that protects against losses due to Urease. Note NBPT = Agrotain Advanced.

Figure 1 - N losses due to Volatilization
Figure 2 - Urease Activity and Soil Temperature
Figure 3 - Ammonia Losses by source and days after application

Which grass herbicide should I use in soybeans for Volunteer Corn?

Three main products on the market. Assure II, Statue and Venture L.

Assure II – labelled until the 6-leaf stage. Label states 0.15 L/ac, you may hear 0.1 L/ac from some in the industry. From experience, at the 0.1 L/ac rate you may see reduction in efficacy depending on plant stage/water volume (way too late at this point in the growing season). Ensure the proper surfactant ratio is maintained at 0.5% v/v. If mixing with a high quality glyphosate (Roundup), you can cut the Sure-mix rate in half (0.25% v/v)

Statue – new in 2019, it is clethodim with a new and improved surfactant. 6-leaf is listed as the maximum size. Carrier (MSO/non-ionic surfactant), must be used with this product.

Venture L – can be used on vol. corn until the 4-leaf stage. One advantage of Venture L is that there is some limited residual activity, which can control later flushes. If used on its own at higher water volumes, consider adding Turbocharge to maintain the surfactant rate.

Straw value Using a value of $650 for MAP and $560 for 0-0-60 the P and K value of wheat straw is about $0.01 per pound of straw. That would make the P and K value of wheat straw $20.00 per ton or $22.00 per tonne. The real value of wheat in a rotation is the roots, breaking disease cycles of other crops weed control and allowing you to plant a cover crop that adds organic matter to soil. Sell any straw you can and plant a cover crop.

Not registered - Do Not Spray

This time of year, every year I am asked about spraying something that is off label. Typically, it is a product that is registered but the time to apply has passed. I often get calls from custom spray folks who have been asked by a producer to make one of these sprays. DON'T DO IT. It is not your fault that the spray did not get on in time. In these cases, it is not the person who asked for the spray, nor the person who sold it but the person who sprayed it that will be held responsible.

New Insecticide from BASF

BASF’s Sefina is an insecticide for soybean aphids and other insects. Sefina is translaminar, so it will move from the top of the leaf to the underside, but it is not systemic, hence it has very little movement throughout the plant. Product functions by causing the insect to experience disorientation, eventually falling off the plant. Full crop coverage is important for optimal performance. Therefore, use higher water volumes (15-20 gal/ac) to ensure adequate coverage to reach the full canopy. Hitting the lower leaves is ideal to ensure best results.

Forages – Why you had Low Protein 1st Cut

One reader commented that his clients were having their 1st cut alfalfa come back with low protein. In conversing with Pioneer agronomist Blair Freeman, his thoughts are some forage producers timed hay cutting by alfalfa bloom rather than the grasses that were fully headed out. Grasses head out based on day length and not on temperature, whereas alfalfa blooms based on growing degree days. Growers waiting for mixed alfalfa stands were left with overly mature grasses, and lower volume alfalfa, leading to an overall low protein 1st cut.

Spraying a Storbilurin fungicide on Spring Cereals in Heading

After speaking with a handful of reps, the consensus is follow labelled application. Stratego Pro is not registered for spring cereals at heading. Headline AMP is, but most would only recommend this practice on Oats, where the risk is much lower for fusarium infection. At the end of the day, avoid applying strobilurin based products on fusarium prone crops such as wheat and barley. Consider it on Oats if labelled. Products labelled for head half emerged are Acapela or Cerefit, and Quilt. Products labelled until the end of flowering are Headline AMP and Trivapro. StrategoPro is only labelled until flag leaf fully emerged.

Barley Yellow Dwarf Virus

If you are seeing yellow or red leaves in the lower canopy in your spring cereals, it maybe Barley Yellow Dwarf Virus. Oats are the most sensitive of the major cereals This virus is vectored by 5 common aphids, most common is bird cherry-oat aphid, which feeds on young cereal seedling plants. Since the disease is vectored by aphids, if you do not have aphids, you will not have infection. This disease is more severe when cool periods are followed by a heat shock (periods of high temperatures). The most effective management tools are to use insecticide treated seed and/or plant resistant cultivars. Early seeding will reduce the risk of damage. Notes from Prairie Oat Growers Manual.

UNL Barley Yellow Virus

Priarie Oat Grower's Manual

Picture 8 - Barley Yellow Dwarf in Oats

MSO vs Surfactant Blends

Many of the post emerge soybean products were designed to be used with a proprietary surfactant/oil blend. Some of these product and actives have since been sold off to generic crop protection manufacturers. In a few instances, the generic product (i.e. Contender – quizalofop-p-ethyl) contains Methylated Soybean Oil (MSO) instead of the surfactant/oil blend (Sure-mix). The MSO is not a suitable substitute for Sure-mix when tank mixing with products like Reflex, Pinnacle or Classic. In those instances, you will have to buy Sure-mix or Turbocharge separately.

What Glyphosate do you use?  (Poll)

Picture 9 - Ontario Growers and Glyphosate Product Use

Main foliar disease robbers in Corn – 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.

Figure 4 - Corn Yield Losses by Disease for NE US and Ontario

Main foliar disease robbers in Soybeans – 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. The next biggest one is Pod and Stem blight. Make sure, at a minimum, the product you are using is controlling white mould.

Figure 5 - Soybean Yield Losses by Disease

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

You are 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 two listed below is a couple of the best I have found. Have something better? Please share.

K-State Soybean Stage Guide (1 Page)

Cool Beans - In-depth Staging Guide

Foliar Leaf Diseases in Adzuki Beans

Adzuki beans seem to be replacing navy or white bean acres in some of the areas I cover. In speaking with Chris Gillard, Dry Bean Researcher at the Huron Research Station, you will still have to spray for white mould. As far as anthracnose, it depends on where the seed is sourced from. If grown in Ontario, it would be prudent to spray for anthracnose. If grown in Idaho, or another dryland environment, anthracnose is less of a concern. That said, the scientific literature is thin on anthracnose occurring in adzuki beans but does occur in other species within the same genus.

"The best source of leverage is creating more value than you capture."

- Shane Parrish