Don’t Give Up on Your ‘Sons & Daughters’

Some Key Agronomic Challenges in Soybean & Corn

By Paul Hermans

If you have children, you know that throughout their life, they can challenge you daily. Ask yourself, have your ever given up on your children?

Consider your crops like your kids, you should never give up on them throughout the growing season. Keep constantly checking your crops and revise management strategies to reduce stress. This will lead to higher yields and profitability.

Two key factors are at play in this strategy:

  1. Knowing the critical periods of a given crops growth cycle with potential stresses that could occur at those times
  2. Scouting, scouting, scouting.

Now that the crop has emerged, what are some management strategies that you can implement to keep the crop flourishing?

In the soybean world, the key to higher soybean yields is setting a large pod load and keeping a large pod load. Did you know only 25 per cent of flowers make it to the pod stage? What can you do to keep flowers happy? How can you fill a large pod load?

Weed control, insect management, and disease control are three avenues to keeping flower and pod development happy.

Weed control issues are hopefully under control by now. Last minute rescue treatments may be warranted.

Watch label restriction rates for when soybeans are flowering or when the growing point for corn is above the ground, as off label rates and applications can lead to reduced yield potential.

Broadleaf weeds are more damaging on a one-to-one plant basis than grasses. Mike Cowbrough, OMAFRA weed management specialist, recently shared that at a weed density of 20 broadleaf plants per meter squared, broadleaf weeds contribute to a 53 per cent potential yield reduction, while grassy weeds could result in a 21 per cent yield loss.

Keep an eye on insects. Weather patterns and drought conditions will assist different insect development.

In soybeans, the main insects of concern are soybean aphids and spider mites.

Soybean aphids are small, yellow aphids with distinct black cornicles – ‘tail pipes’ – that can produce up to 15 generations in a summer. This devastating pest removes moisture and nutrients from the plant needed for grain production.

Aphids on a leaf
    Martin E. Rice photo

An insecticide seed treatment provides up to 45 days of protection from aphids. Scout fields that are early planted or fields that were planted without an insecticide seed treatment.

In 2022 in Eastern Ontario, we had a severe outbreak of soybean aphids. Gilles Quesnel, an independent agronomist conducted some research work at the Winchester Research Station. His data showed a six-to-nine-bushel yield response to aphid control using Sefina insecticide. When factoring in application costs and tramping losses, the return to spraying equated to $75 to $117 an acre (at $18 per bushel commodity price).

Spider mites are opportunistic. During dry, hot years they will move in from field edges (when vegetation becomes dry and feeding opportunities limited) and will move into soybean fields around the edges first. Keeping a close eye on this pest will ensure feeding and yield losses in your soybean crop are kept to a minimum.

Lush tall beans can be a sign of the risk of white mold disease. Pay special attention to the canopy development and forecast leading into July. Once flowering starts (R1, one flower anywhere on the plant), with moist soil conditions, humidity within the crop canopy, and a history of mold in the past, mold can take over.

In 2022, Pioneer conducted fungicide trials in Eastern Ontario. On four trials, yield data showed a 7.1-bushel advantage utilizing Viatude fungicide compared to the untreated check.

Switching to corn, producers should be keeping an eye on western bean cutworm, corn rootworm and leaf diseases.

Jonathan Zettler, an independent agronomist who runs Field Walker AG in Southern Ontario mentions to keep an eye on western bean cutworm.

“Western bean cutworm continues to be an increased issue in my area when it comes to corn.

“Ensure you have your traps already set up at that point so you can monitor for peak flight. Scouting fields and observing maturity differences, especially with tasseling can be helpful when scouting for western bean cutworm.”

Jonathan mentions scouting that pass at tasseling can also show planter performance differences.

The use of pheromone traps can help determine when to start scouting for egg masses, which usually occur around VT to R2 stages in corn. The use of foliar insecticides is recommended when threshold levels have been met, unless you are planting trait specific corn with protection against western bean cutworm.

Heading into tassel time, planning for corn fungicides and keeping an eye on leaf diseases will depend highly on your geographic location.

New to the corn leaf diseases, tar spot has been a devastating disease that gripped parts of Southern Ontario throughout the 2021 growing season. In 2022 it was limited in scope due to hot dry weather.

Hence the need to scout, scout, scout.

Other diseases, like grey leaf spot and northern corn leaf blight, can rear their ugly head.

Corn Leaves with Various Diseases
    (photo 1) - Tar spot in corn. (photo 2) - Corn ear leaf with large northern leaf blight lesions on susceptible hybrid. (photo 3) - Corn leaf with gray leaf spot lesions. Paul Hermans photo

Research work would tell us that corn-on-corn, reduced tillage, and planting corn hybrids with lower disease ratings would be candidates for potentially higher disease pressure and fungicide response. Talk to your seed representative on disease rating scores for your corn hybrids.

When walking fields, compare lower and upper leaves for disease. Diseases that come from the ground (crop residues) will be found on lower leaves. In contrast, diseases found in the upper canopy have been blown in from outside the field boundary by high winds and storm events.

Chart Showing Fungicide Yield Advantage
    Average yield response to foliar fungicide applications as influenced by tillage and previous crop in on-farm trials (374 trials 2007-2014). N=number of trials. *insufficient data. Source Corteva Agriscience-Crop Insights.

Yield response to foliar fungicides was examined by Corteva Agriscience across grower, industry, and academic trials. In 1,241 trials from 2007 to 2015 across North America, the average yield response to a foliar fungicide was 7.9 bushels. No surprise, yield advantages were higher in normal to above normal precipitation years.

Chart Showing Fungicide Corn Yield Advantage
    Average corn yield response to foliar fungicides in Iowa on-farm trials in drought years (2011-2012) compared to years with normal or above-normal precipitation (2007-2010 and 2013-2014).

Corn rootworm is a pest that is ever evolving.

Monitor corn fields for adult beetles to get a sense of pest levels. If you’re planting second-year corn, a sound pest management strategy is needed to prevent long-term resistance to Bt-traited corn.

In certain areas, the corn rootworm is laying eggs in corn that are surviving into next year’s soybean rotation. Following the soybean crop, the eggs hatch in the next year’s corn crop.

This phenomenon is known as extended diapause. Utilizing sticky traps is a fantastic way to see where populations are high or low in your fields.

Glue Traps from Field
    Use glue traps as a way to keep an eye on pests. Paul Hermans photo

I highlighted some of the key agronomic challenges soybean and corn growers will have to scout for in Ontario. Other factors such as fertility, drainage, and other pests and diseases need to be monitored as well.

In the end, with today’s commodity prices combined with the cost of growing a successful crop, keeping a close eye on “your sons and daughters” will help you reap great rewards when they grow up! BF

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