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Midwest agronomists talk late June crop progress

Winfield United agronomists in eight states offer detailed look at corn and soybean issues as of June 23, 2017.

A lot of talk about corn variability across the Midwest, due to wet weather, standing water, replanting and now potential dry soils. Sidedressing is still going strong in some areas. Scouting has led to decisions about weeds, insects and diseases. Read on to learn advice from agronomists in Illinois, Indiana, Iowa, Michigan, Minnesota, Ohio, South Dakota and Wisconsin. They discuss everything from corn variable that will impact yield, sidedressing, scouting, dry soils, fungicide applications, resistant weeds, tissue sampling and more.

 

Illinois - reported June 19

Variable. That’s how WinField United agronomist Sara Smelser is describing the early-season status of Illinois crops. The long planting season, fueled by wet weather and replanting, means corn is anywhere from the V5 to V10 growth stage in most parts of the state. Within individual fields there is variability where spot planting occurred or where standing water remained after excessive rains. Smelser says growers could see yield impacts where environmental conditions weren’t conducive for even plant emergence this year. Overall, she says soybeans escaped the pressure of excess rain where planting occurred late. Despite all the early moisture, corn is beginning to show signs of drought stress in some areas of the state due to recent high temperatures and lack of rain.

Current field activities include sidedressing nitrogen and applying postemergence herbicides to manage weeds that are beginning to break through early-season residual applications. Scouting for pests is also top of mind because insects and diseases are starting to appear. Smelser says stink bugs, rootworm larva and slugs are common in corn. Disease pressure is also a concern, with southern rust popping up in corn and frogeye leaf spot showing up in soybeans. She recommends that farmers evaluate disease and insect pressure now so that timely fungicide and insecticide applications can be made if they are warranted.

With the launch of new soybean trait and herbicide technologies, low-volatility dicamba use is on the rise. Smelser reminds farmers to follow label instructions for proper use of the new dicamba herbicides to get the most value from the technology and to prevent off-target movement to susceptible crops. The current in-season labels allow application through the R1 stage (beginning bloom) in Roundup Ready 2 Xtend soybeans.

 

Indiana - reported June 21

Consistent with other Corn Belt states, crops in Indiana are highly variable this year, says WinField United agronomist George Watters. The state struggled through a wet, cool spring that resulted in delayed planting and the need for replanting. Corn stages range from V1 to V10; the most advanced crops are found in the southwestern part of the state. Watters says good-looking fields can be found, but the vast majority are suffering from uneven growth and thin stands. Less than half of the corn in the state is rated in good to excellent condition at this point, and nutrient deficiencies are starting to appear.

The rough start to the season will make it challenging to reach yield potential this year. Reduced stands, variable emergence and compromised root systems are adding extra stress to already-struggling plants. Wet weather and inconsistent emergence have also made weed control difficult this year, as many crops emerged without the benefit of preemergence residual herbicides. There will be extra pressure to make timely postemergence herbicide applications to keep weeds at bay, Waters says.

At this point, farmers should be evaluating the nutritional status of crops while there’s still time to make in-season adjustments. Watters recommends a NutriSolutions tissue analysis (http://www.winfieldpro.com/Tools/NutriTech-Tool.aspx) to confirm levels of sulfur, boron and nitrogen in corn, which are more likely to leach with excessive wet weather. Watters says nitrogen modeling tools can help project the nitrogen status in fields. Using these technologies and tools to help guide management decisions will be key to optimizing profitability in a challenging year.

 

Iowa – reported June 22

Corn and soybeans in Iowa look good at this point in the season, says WinField United agronomist Darrin Roberts. Corn plants are starting to enter a period of rapid growth in which plants have a high demand for both water and nutrients. Soybean plants are beginning to flower.

Early rain has created a number of challenges for farmers in the state. Some fields that were planted into wet soils are showing the effects of sidewall compaction, with some plants struggling to develop a good root system. Farmers are also adjusting their postemergence herbicide application plans since early season rains kept them from applying preemergence herbicides in a timely manner. Roberts reminds farmers that herbicide applications are most effective when weeds are 2 inches or less in height.

There has been minimal disease and insect pressure to date, but farmers should scout fields regularly to keep up with any issues that may develop. If crops look challenged now, it’s a result of the environmental conditions the crop faced after planting. Cool and wet conditions after planting led to uneven emergence in some fields, and also created a suitable environment for different pathogens to enter the young seedlings.

Fields that endured heavy rain after planting, followed by dry conditions, are showing rootless corn syndrome. In fields where a soil crust formed after planting, soybeans snapped off trying to push through the surface, requiring replanting in some areas.

Evaluating nutrient status is essential right now, adds Roberts. He encourages farmers to take tissue samples and perform soil tests to evaluate crop nutrient status, and also to use a nitrogen model, which is provided in many ag technology tools.

 

Michigan – reported June 21

Regarding corn, many Michigan fields are near the V5 growth stage and ready for nitrogen sidedress as field conditions allow, says Jason Roth, agronomist with WinField United. While corn was transitioning from a seedling root system to a nodal root system, issues with root establishment and development were evident. For example, several wind events caused poorly rooted corn plants to tip over or lose leaves. Also, Michigan’s cool weather has resulted in late planting and slowed overall crop growth.

There have been some sulfur and zinc deficiencies, particularly on corn planted in coarse soil types, Roth notes. For sulfur-deficient corn, farmers have the option to combine a liquid sulfur product with their side-dress nitrogen applications. Another option is a foliar application of sulfur or zinc, depending on what is needed, which can be conveniently added to a postemergence herbicide application.

A fungicide application in corn can also be a good idea, especially with a strong crop. Farmers should consider a fungicide application between V5 and V10 to help protect the corn crop, particularly in corn-on-corn fields, in no-till systems or with hybrids that have weak disease-resistance scores.

Roth has received some reports of cutworm injury to corn plants, with armyworm also beginning to make an appearance. Corn pests that will be appearing shortly are European corn borer (in non-traited corn) and western corn rootworm. A good indicator for western corn rootworm is that, when eggs hatch, farmers will also see fireflies at night.

In soybeans, a number of seedling diseases take hold, particularly Pythium. Roth has seen damping off in soybeans, in some cases due to seed-corn maggot feeding which increases seedling susceptibility to early season pathogens Unfortunately, once a soybean stand has been compromised with a seedling disease, there’s no recourse. Using a good seed treatment with both a fungicide and an insecticide for next year’s crop would be a valuable investment, says Roth.

Farmers who planted into standing marestail are now trying to eliminate it, and there is very little they can do because it is resistant to so many herbicides, Roth notes. Most postemergence herbicides are not effective. The best solution is to plant into clean fields, using a spring burndown herbicide application or tillage to clean up the field, followed by a soil-residual herbicide application to control the marestail before it emerges. Lambsquarter is also flushing, and Roth advises growers to control it while it is small with an herbicide application now.

Residual herbicides should be applied about 30 days after planting, with overlapping residual herbicides placed in areas that need it, especially those that struggle with waterhemp or Palmer amaranth.

 

Minnesota - reported June 21

Corn crops look mostly good, but definitely not as good as crops could look in mid-June, says Mark Glady, regional agronomist for WinField United. This situation is due to a variety of factors, including planting into wet fields, late planting and recent storms.

On June 11, a storm caused multiple hail events in isolated areas. Some cornfields were demolished by hail below the growing point and there’s absolutely nothing left, says Glady. Unfortunately, replanting corn for grain in mid-June is not a good option in Minnesota. It may still be feasible to plant corn silage to replace those lost crops or to plant a cover crop.

Most corn is currently between the V6 and V8 growth stages, says Glady, and this is the tail end of topdress or sidedress season for corn.

Moderate rainfall has allowed good activation of preemergence herbicides and good residual activity from those herbicides to help keep weeds down. Favorable weather during the last two weeks has helped to get postemergence herbicides applied, and weed control in corn has gone well so far, he notes.

Right now is the end of the sweet spot to take tissue samples to identify any nutrient deficiencies. Corn is entering its rapid growth stage, so using tissue and soil samples to identify nutrient deficiencies and correct them quickly is critical, says Glady.

Although many soybean fields were planted later than optimal, there has been good residual activity from preemergence herbicides, and now plants are getting to the point where they need to be sprayed.

However, many fields were planted quickly on Mother’s Day weekend without enough time to apply a preemergence herbicide. As a result, there were issues with giant ragweed in those soybean fields, with few postemergence options available to manage this weed, says Glady. However, farmers are doing what they can to combat the problem.

It’s very important to apply a soil-applied residual herbicide, he says, because small soybean plants have a ways to go before they get to canopy, when rows can be shaded to prevent other weeds from emerging. An in-season residual herbicide can get soybeans to the canopy before another flush of waterhemp or other weeds emerge.

Also, iron deficiency chlorosis (IDC) has just exploded, causing a number of yellow soybean plants in high pH soils. If farmers weren’t able to get liquid iron on in-furrow, a foliar iron application could help alleviate some of that stress. However, Glady cautions that foliar iron is not as effective as applying iron in-furrow and the best time to spray foliar iron is just prior to or right at the onset of yellowing. For some farmers, now may be too late, though some may still have time to benefit from this application, says Glady.

Another concern is weed control with dicamba-tolerant soybeans. Glady notes that in his area, during the first couple of weeks of spraying dicamba on dicamba-tolerant soybeans, farmers have seen better weed control by adding a methylated seed oil (MSO) to the tank and increasing the volume of water sprayed per acre.

 

Ohio - reported June 23

Spring’s heavy rains and overcast skies have hampered crop growth and development in Ohio, says Joe Rickard, WinField United agronomist. There are also a wide array of field concerns present, including bean leaf beetles, armyworm and leaf hoppers.

On average, current growth stages for corn vary from V2 to V8, with soybeans ranging from VE to V5, depending on where the farm is located in the state. Fields that were planted during the last two weeks of April look much better than those that were planted in May, which had only a handful of days that were suitable for planting.

Rickard urges farmers to work with their agronomists to help them scout and keep a watchful eye on their fields. Especially as the weather turns hotter, proactively scouting for insects and diseases will be key to keeping crops healthy. Farmers should layer their residual herbicide programs to keep weeds in check.

Farmers who are sidedressing or getting ready to sidedress want to know how much nitrogen is left from what they applied earlier in the year, says Rickard. He recommends doing a Pre-sidedress Soil Nitrate Test (PSNT) (http://www.cornandsoybeandigest.com/soil-health/tips-accurate-pre-sidedress-nitrate-tests) to evaluate current ammonium and nitrate levels in the soil.

 

South Dakota – reported June 23

WinField United agronomist Kyle Gustafson reports that overall crops are looking okay in the state, despite extreme weather conditions. Some areas saw excessive rain, while others were excessively dry during the past month. Recent moisture has helped where conditions are dry, but it also brought hail to localized areas. On average, corn is at the V6 growth stage across the state, but soybean progress is more variable. Early crusting of fields resulted in soybean replanting, so progress ranges from recently planted to V2 or V3. As the days shorten, expect soybeans to begin flowering.

Preemergence herbicide activity has been reduced due to dry weather, so in-season weed management will be crucial. Regular scouting, coupled with timely herbicide applications when weeds are 2 to 3 inches tall, will provide the most effective postemergence weed control. Gustafson reminds farmers to follow herbicide label application timing to avoid crop damage and to achieve adequate control. He says most postemergence corn herbicides can be applied until corn is 11 inches tall, or until the V5 or V6 growth stage depending upon the label. For soybeans, in-season herbicides should be sprayed by the end of R1 (first flower) or R2 (full flower), depending on the label. If you are past the timeframe to apply the herbicide you had intended, Gustafson recommends consulting with your local agronomist to adjust plans.

While weed control is the focus right now, Gustafson reminds farmers to evaluate crop health, as signs of nutrient deficiency may begin showing up in areas of excessively wet or dry weather. He recommends a Pre-sidedress Soil Nitrate Test (PSNT) (http://www.cornandsoybeandigest.com/soil-health/tips-accurate-pre-sidedress-nitrate-tests) and tissue sampling to determine whether an in-season nutrient application would benefit crops before the critical nutrient uptake period begins.

 

Wisconsin - reported June 19

Because of replants and late planting, growth stages in Wisconsin cornfields currently range widely, says Kevin Sloane, national technical seed manager for WinField United. Some fields have just been planted; however, other corn plants are between V6 and V7.

Soybeans are at third to fifth trifoliate, again due to late planting and replants. As with corn, some soybeans are just emerging and a few acres are yet to be planted. There is much variability in growth levels across the state, even within fields of both corn and soybeans, says Sloane. This variability is primarily due to the wet conditions that pushed farmers to plant fields in slightly wet conditions that were less than ideal. This resulted in crusting, sidewall compaction and other agronomic issues.

As a whole, Sloane notes that stand qualities (population, singulation and plant-to-plant staging) in both corn and soybeans are below what farmers would like to see.

As the season progresses, the key crop management activity will be for farmers to assess what their situation is. For corn, this means digging up plants to see if there are any issues with root restrictions or washing out of the seed furrow, for example.

Above ground, it’s a good idea for farmers to take some tissue samples to identify current plant nutrient levels and talk to their local agronomists about options going forward, says Sloane.

In corn-on-corn fields, now is the time to start thinking about potential V5 to V6 fungicide applications, which can easily be combined with postemergence herbicide applications.

Lastly, Sloane reminds farmers that, with the plentiful moisture and heat we have had recently, weeds are taking off extremely fast. Remember to keep weed height, weed species and weather in mind when making applications. Farmers should consult their local agronomists about adjuvant recommendations, guidance on tank mixes and how to best use multiple modes of action for weed-resistance management.

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