The Effect Aphids Can Have on Corn Yield

August 26, 2019

     

While walking in corn fields this past week I noticed the corn aphid population has dramatically increased. A few  weeks ago it was hard to find any corn aphids, but now they are making walking corn very uncomfortable. This particular corn field was in West Central Iowa and was treated with fungicide and insecticide two weeks prior.

Corn aphids are becoming a common pest for corn growers and have the potential to develop into massive populations. Aphids can be found throughout the corn-growing season, but post-pollination corn aphids are a relatively new issue. It’s important to understand the damage aphids can cause to determine if management is necessary.

Here are a few facts you should know about corn aphids:

  • Aphids feed on the sap from the plant phloem and excrete sugar-rich honeydew that covers the plant, which can interrupt both plant growth and pollination. Aphids colonize deep within the whorl. Excessive feeding within the whorl before tassel emergence leads to incomplete kernel development or barren ears.
  • Aphids are problematic during tasseling and can colonize corn later in the summer, threatening yield potential. Drought-stressed corn plants also can be sensitive to aphid feeding.
  • Beneficial insects, such as ladybugs, can help control aphids.
  • In extreme cases, aphids are associated with dying leaves or, rarely, the death of entire plants. Sooty molds can colonize these sugary leaf surfaces, further reducing leaf photosynthesis.
  • Aphids can, and often do, leave corn as it begins to mature to dough stage.  If subsequent rainfall washes off the sooty mold, honeydew and cast skins, the only evidence of the infestation may be small discolored areas on the leaf sheath and shanks.

Management Tips:

  • Spot damage: Heavily infested plants are discolored and stunted with wilted, curled or yellowed leaves and sometimes shriveled ears.
  • Scout: Start scouting three weeks before tasseling. Check five locations within the field and 20 plants at each location.  Examine the ear, leaves and stalk.
  • Control before tassel emergence: Protect yield by controlling aphids two to three weeks before tassels emerge. Treat plants if 50 percent are infested with colonies of over 75 aphids per plant.
  • Manage late-season: Treat if more that 50 percent of the tassels are covered with aphids and their honeydew, before pollination is halfway complete.
  • Historically, little attention has been paid to the late-milk stage bird-cherry oat populations. 

Summary:

  • Aphid infestation can lead to significant yield loss in corn.
  • Aphids can populate quickly and cause extensive damage.
  • Post-pollination aphids rarely cause significant yield loss.
  • Scout and treat fields before tasseling to prevent costly damage.

-Eric Solberg, Eastern Region Product Agronomist


Categories: aphids, Corn     Comments: 0     Tags: aphids    

Two Foliar Diseases to Start Scouting

August 5, 2019

Now that it’s August, a good percentage of the corn has tasseled, and it’s time to be scouting for foliar disease in your corn fields. 

There are two main foliar diseases in the Western Corn Belt:

  1. Gray Leaf Spot (GLS). This is the most common disease we see in the area. GLS survives in infested residues from previous corn crops. We see it almost every year at varying levels depending on hybrid tolerance and weather. Learn more about GLS here.
  2. Southern Rust. This is another disease we are seeing in the Western Corn Belt. Southern rust has made its way through Oklahoma and Kansas and has now been confirmed in Southern Nebraska. Southern rust thrives in warm, humid environments, so irrigated corn country in Nebraska is a perfect home. Learn more about southern rust here. 

Foliar diseases can cause significant damage to corn yields, but with a little scouting and a fungicide application, you can protect your corn crop.   

-Craig Langemeier, Western Product Agronomist


Categories: corn, gray leaf spot, southern rust     Comments: 0     Tags: foliar diseases, gray leaf spot, Southern Rust    

Advanced Planning for Disease Control

July 10, 2019

With the rough start to our region’s growing season, we need to start thinking about keeping our fields strong and healthy all the way to harvest. With favorable weather this growing season we still have the potential to grow a high yielding crop, despite being planted late. Below are fungicide efficacy ratings for several products out on the market, as well as a link to the UNL plant disease website. If you have any questions regarding disease problems in your fields, contact your Hoegemeyer product agronomist for help determining the best plan of action.

Resources:

https://www.extension.purdue.edu/extmedia/BP/BP-160-W.pdf

https://cropwatch.unl.edu/plantdisease/corn

- Jonathan Williams, Southern Region Product Agronomist


Categories: corn, Disease     Comments: 0     Tags: Goss's Wilt Corn Disease    

Interesting May Weather - Let's Talk Replant Considerations

May 8, 2019

This spring has been a whirlwind of weather patterns throughout our region. While many farms have corn and even soybeans out of the ground, and others are still weeks away from planting, knowing your options for the possibility of a replant before that seed gets put into the ground can ease some tension if the problem may arise.
 
First and foremost, know that as a 100% by-crop customer of Hoegemeyer that is planting products with the LumiGENseed treatment, you have the opportunity to get your replant seed for FREE*. Even if you are not a 100% customer, know that, under some conditions, you may still have this opportunity. Speak with your DSM or Agronomist to learn more.
 
It is also important to consider the potential for yield loss from delayed planting due to replant. The possibility of a reduced stand in your first planting may still be more feasible than the potential yield loss due to a shorter growing season that your replant seed will have to deal with. While every situation is different, the main points to consider no matter what weather or planting situation you’ve been dealt is outlined below.
 
  • Planting date - and possible planting date of the replant
  • Expected stand loss
  • Hybrid or variety planted 
  • Soil conditions that may hinder any growth problems into the future

In summary, if you feel you may need to replant or have unexpected stand loss, don't hesitate to reach out to your local Hoegemeyer representative so we can evaluate options. Evaluating and resolving these issues as early as possible will get you on track to having the best opportunity for a successful crop.

 

- Jonathan Williams, Southern Team Product Agronomist

 

*Refer to 2018-19 Hoegemeyer Business Manual for specific Replant Program Guidelines

 

Components of LumiGEN technologies for soybeans are applied at a Corteva Agriscience, Agriculture Division of DowDuPont production facility, or by an independent sales representative of Corteva Agriscience or
its affiliates. Not all sales representatives offer treatment services, and costs and other charges may vary. See your sales representative for details.
Seed applied technologies exclusive to Corteva Agriscience and its affiliates.®, TM, SM Trademarks or Service Marks of Dow AgroSciences, DuPont or Pioneer and their affiliated companies or respective owners.

 

Categories: Corn, Replant, Soybeans     Comments: 0     Tags: Corn, Corn and soybeans, Jonathan Williams, LumiGEN seed treatment, replant guidelines, Soybeans    

Corn Seedling Injury & NH3

April 24, 2019

Anhydrous Ammonia, commonly called NH3, is one of the most commonly used sources of Nitrogen used by corn growers. NH3 is applied by injecting the gas into the soil 8-10” deep, a minimum of 5-7 days before planting. It is preferred to apply NH3 in the fall, if time and mother nature allows. Unfortunately the fall of 2018 made this a very challenging task. Spring-applied NH3, which carries more risk, is necessary when fall applied is not an option. Please take these items into consideration when using spring-applied NH3.

 

  • Applying the ammonia at an angle or parallel with the corn row at least 4-5 inches to the side will minimize the potential for seedling injury.

  • Distance and time:  The further the application from the seed and the longer you wait to plant, the better for the germinating seedling.

  • If you can’t wait 5-7 days after NH3 application to plant, apply the ammonia as deep as possible (8-10”).

 

Anhydrous Ammonia when injected into wet soils and not applied deep enough can cause injury and stunting of seedling corn roots (Figure 1). Most of the Western Corn Belt is experiencing a wetter-than-normal spring. NH3 applied to wet soils can cause sidewall compaction which can let the anhydrous ammonia move up the application channel into the seed zone. When this is done, you have the potential to have root burn like shown in the photo above. Corn plants that appear wilted and spindly (Figure 2) are a symptom of anhydrous injury to the roots.  

 

Growers who are using high-speed, low-draft applicators don’t have the option to place anhydrous ammonia 10” deep.  Research has shown that applying high rates of nitrogen with these systems can result in significant seedling burn if planting directly over the injection zone (Fernandez et al., 2011).  

 

Applying anhydrous ammonia well in advance of planting allows for the NH3 at the injection point to be converted to NH4+.  Five to seven days or longer is the standard recommendation between application and planting, but free ammonia will persist longer in cooler drier soils.  Reducing risk of injury involved separating the ammonia from the seed/seedling by either time or distance.

 

Summary:

When spring seems later than usual, it is very tempting to sneak out into the field early and get your Nitrogen on. Please ensure the soil is dry enough and the applicator is applying 8-10” deep when you apply anhydrous ammonia. Keeping stress off these emerging seedlings will lead to higher yields in the fall. Waiting until field conditions are right will give your corn crop the best chance to succeed this year.

 

- Eric Solberg, Eastern Region Product Agronomist

 

Source: Fernández, F.G., D.B. Mengel, and J.E. Sawyer. 2011. Some things to consider for shallow placement of anhydrous ammonia. Proc. of the 2011 Wisconsin Crop Management Conference, Vol. 50


Categories: Corn, Eric Solberg, Management     Comments: 0     Tags: 2019 Planting, Anhydrous Ammonia, corn, Corn Seedling Injury, Eric Solberg, Management, NH3    

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