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:
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.
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.
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.
Within the Hoegemeyer footprint we have corn at many different stages of growth depending on when producers could get into the field. In our southern regions, we have corn well over our knees. As we move into Nebraska there is corn anywhere from knee high to emerging. As we move into northern Iowa and southern South Dakota there are a lot of planters rolling as I type this since mother nature is finally cooperating.
Something we have been noticing in corn that is further along is Rapid Growth Syndrome. Certain genetics seem to be more prone to this and we will see some “repeat offenders” that seem to have this issue every year. The corn always comes out of it, but if you see corn with twisted whorls this article gives you a good background on why this happens.
As always if you have any questions feel free to call your Hoegemeyer DSM or agronomist.
-Craig Langemeier, Western Region Product Agronomist
This year has been another season of extreme weather from very little planted in the north and good planting conditions in the south to storms and possible replant in the middle of the Hoegemeyer footprint. Because of all these weather events and planting timings it is important to be able to stage your corn growth. Staging the corn growth enables you to understand when the optimal time is to apply fertilizers, spray post applied chemicals, spray fungicide and to scout for certain insects.
Corn growth stages are defined into two stages, first comes the vegetative stages (V) and reproductive stages (R). The vegetative stages are divided into substages V1, V2, V3, etc. identifying the number of leaf collars. The reproductive stages are divided into substages R1, R2, R3, etc. identifying ear development.
Staging A Corn Seedling
Each leaf stage is defined according to the uppermost leaf whose leaf collar is visible. The first part of the collar that is visible is the back, which appears as a discolored line between the leaf blade and leaf sheath. The characteristically oval-shaped first leaf is a reference point for counting upward to the top visible leaf collar.
Emergence & Stand Establishment
VE Stage – This is emergence and takes place approximately 100-120 GDU’s or 4-5 days. The seed will need to take up approximately 30% moisture to begin germination.
V1 Stage – The first leaf to become visible will have a rounded tip and all other leaves after that will be pointed. The leaf will come out approximately 3-4 days after VE.
V2 Stage – Will take place approximately 200 GDU’s or 7-10 days after VE.
V3-V6 Stages – Will take place approximately 475 GDU’s or about 21 days after VE. This marks the end of the seed being the main source of food for the plant and the beginning of photosynthesis and the nodal root for food. The number of kernel rows are being determined. Growing point is starting to come out of the ground.
V7-V9 Stages – Will take place approximately 610 GDU’s. This is a good stage to do any foliar treatments because it is the beginning of rapid growth and nutrient uptake.
Rapid Growth & Dry Matter Accumulation
V10-V13 Stages – The plant has entered its fast growth stage. New leaves or V stages will happen every 2-3 days. Water and nutrient demand is great during this period. As growth works it way to V13 the ear will determine how long the kernel rows will be and complete the determination of ear size. In general, earlier season hybrids will move through these stages in less time. We will be a good 6 weeks after emergence.
V14-V(n) – This is the final stages of the vegetative growth of the corn plant. Depending on growing conditions and the location of the field in the corn belt will determine the number of leaves on the plant. In general, most plants will be around 16-22 leaves. At V15 there is only 12-15 days until the reproductive stages begin. Root growth is ramped up to support the taller plant with an ear. Roots could reach 5-8 feet deep at this point.
VT Stage – This is when the tassel is completely visible. The tassel will appear 2-3 days prior to silk emerging R1. Pollen shed normally occurs during the late morning or early evening. This is when most fungicides are recommended to be applied.
R1 Stage – Silks will appear, and pollination will begin. This process normally takes 2 -3 days. There is rapid uptake of nitrogen and phosphorus.
R2 Stage – Blister looking kernel is forming on the cob and will continue to grow through R6. The cob is in its full size.
R3 Stage – Milk occurs about 18-22 days after R1. Corn kernels will start to yellow and the kernel growth will occur from cell expansion and starch accumulation.
R4 Stage – Dough is when the kernels start to thicken and accumulated 50% of their dry weight.
R5 Stage – Dent the kernel is around 55% moisture. This is where livestock producers will watch for the milk line to move from the top of the kernel to the tip for silage cutting.
R6 Stage – Physiological maturity has been achieved about 55-65 days after R1. The tip of the kernel will appear black and is called black layer. The kernel moisture at this point is 30-35% and dry down for grain harvest will start.
Corn development stages is an important part of managing your crop throughout the year. Today you need to know when it is safe to spray your post herbicides and to understand when the plant needs the most fertility. As you can see above the ear determines the number of kernels two different times during its growth, V6 and V12. Understanding your corn fields and hybrids give you a much better chance of managing corn development for a greater chance of higher yields.
-Stuart Carlson, Northern Region Product Agronomist
2019 Planting, Corn Development
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 LumiGEN™seed 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.
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