Join us live this morning as we discuss how to plan for Soybean Cyst Nematodes and Sudden Death Syndrome this spring. #AskTheAgronomist
0:45 Topic introduction
1:41 SCN economic impact
3:01 SDS economic impact
3:36 Managing SCN & SDS
7:50 Data Forward Program can help
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Latham Hi‑Tech Seeds
Ask The Agronomist: SCN & SDS
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Latham Hi‑Tech Seeds
Test for Soybean Cyst Nematode
One comment I often hear from farmers is “I just can’t seem to get an increase in soybean yields as I do for my corn yields.” This is the perfect time of year to reflect on the growing season while analyzing yield results. It’s also the best time to sample for soybean cyst nematodes.
What is SCN?
Soybean cyst nematode is a microscopic ground worm. When analyzing soybean roots, it’s important to correctly identify the difference between nitrogen-fixing nodules and cysts. Nodules for nitrogen production are larger and the size of a pea. Cysts are microscopic and smaller than a grain of sand.
One of the biggest challenges when identifying SCN is that it is not accompanied with many symptoms, but can cause up to a 30% yield loss. Usually SCN shows up in hot spots, where you can see severe stunting, yellowing, shorter crop, lack of canopy or early maturity. These symptoms tend to show up on lighter soil or during tough growing seasons. Wherever soybeans are grown, typically SCN is an issue. Below are two maps to show the growth of SCN over the years.
What is the life cycle of SCN?
Essentially the cyst is the life cycle of a nematode. Juvenile nematodes come in and infect the root. Typically, just the females feed on the root which takes away nutrients from the plants results in a loss of yield. They will then mate and produce eggs. When they produce eggs, they expand in the root, erupt and spread 20 to 500 eggs throughout the soil. The cysts then harden on the root and the process begins again.
In Iowa, we can see that happen for at least three generations per season. Each cyst can have between 20 and 500 eggs inside, creating opportunity for juveniles to come back and begin feeding on the soybean root.
Once the eggs get in the soil, it’s important to understand the number that you have in the soil. Those eggs can stay dormant year-over-year in the soil. Since these eggs are so small, they require very little oxygen to survive.
Management of SCN
The most important management practice of SCN is IPM – Integrated Pest Management. In the Midwest, having a corn and soybean rotation is a great start. Corn is not a host crop whereas soybeans are. I also suggest soil sampling this fall to identify the egg population in your soil. Pull a core from about 8 inches down, right next to the soybean plant right in the root zone.
I also advise to stay away from sampling in the middle of a hot spot for SCN. Often the eggs are concentrated along the edge of the hot spot, so sampling that area will give most accurate results. Population thresholds vary by state. I suggest looking closely to your management practices if results are anywhere from 2,000 – 5,000 eggs per sample. Once you know what is in your field, you can begin to manage it.
Here are three ways to help manage this pest:
- Plant Latham® brand resistant soybeans. Reference product characteristics on our website to identify the disease rating
- Use Latham SoyShield Plus® with Saltro® seed treatment. This will fight SCN and Sudden Death Sydrome.
- TALC USA. Protect corn and soybeans against parasitic nematodes.
Feel free to call into the Latham Seeds office or email me at phill@lathamseeds.com with any questions.
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Latham Hi‑Tech Seeds
#AskTheAgronomist: Soybean Cyst Nematode
Is SCN really a problem in your fields? Tune in to find out! #AskTheAgronomist
:40 — Topic introduction2:10 — What is SCN?2:50 — The life cycle of SCN6:20 — Soil sampling8:55 — SCN egg populations9:45 — Product selection for 2020The maps below sourced from ISU show the growth of SCN from 1990 to 2017.
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Latham Hi‑Tech Seeds
Product Observations Can Identify Seed Needs
Latham product team members have been busy traveling to our SuperStrip™ and other research plot locations across the Upper Midwest.
It’s our job to take notes to help our company offer the best possible product lineup, as well as to assist our customers in choosing the best products for their given situations.
We also encourage you to take notes on your own fields to help identify your seed needs for next year. We recommend keeping an eye out for the following:
Physoderma in corn: While this isn’t a new disease, it’s been getting more publicity recently because some fields have suffered economic damage. Physoderma is a soil-borne fungus that seems to surface when there are warm early season temperatures followed by rainy periods, causing water to sit in the whorls during the v5 to v9 stage. Sporangia release huge amounts of zoospores that can literally swim their way to attack plant cells. Leaf symptoms include yellow-to-brown spots on the leaves and dark purple oval spots along the midrib. The real damage happens on the lower nodes of the plant that become weak and thus susceptible to breakage. Look for a brown to black ring of decay around the node. I’ve heard reports of fields in Illinois where 75% of the plants have broken. While physoderma seems to be more of a problem on the eastern side of our area, it has been identified in Nebraska.
Soybean Gall Midge: This insect pest is so new that entomologists aren’t entirely certain what species it is. It was reported in Nebraska in 2011 and South Dakota in 2015. Just last fall SGM was recorded in 69 counties of Nebraska, Iowa, Minnesota and South Dakota.
Sudden Death Syndrome and White Mold: Scout your fields all the way to maturity, So you don’t have any big surprises come harvest. Also remember to plant Latham® IRONCLAD™ products in these affected areas in the future. I’ve heard of some areas In southern Iowa and northern Illinois that are showing signs of Frogeye Leaf Spot, but I haven’t seen any of those myself – yet!
Weed resistance continues to be a growing issue. Last year I noticed serious problem fields in Wisconsin. Previously, Wisconsin farmers controlled weeds with glyphosate and some tank mix combinations. It’s becoming very obvious that weed resistance in Wisconsin is catching up quickly with the rest of the Upper Midwest. Exercise your weed control options in 2019 with Independent Latham Hi-tech Seeds.
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Latham Hi‑Tech Seeds
Scout for Soybean Gall Midge
Gall midge larvae and damage under the soybean stem epidermis. Photo by Dr. Bruce Potter, University of Minnesota Soybean Gall Midge (SGM) caused extensive damage in 2018. It already has been reported in Iowa, Minnesota, Nebraska and South Dakota this season.
Scout around the edges of your soybean fields, especially those areas that are closest to fields where SGM was spotted last year. The adult stage of this pest is a fly from the genus Resseliella. The adult insects are so small that they go unnoticed in everyday scouting activities. Other midge flies are the Hessian Fly and the Wheat Blossom Midge.
The SGM may be spotted in the larval stages as they feed on a variety of items like decaying organic matter, fungi and, of course, galls on the stems of plants. Affected plants will appear wilted and eventually die.
Wilting also is symptom of Phytophthora Root Rot and Fusarium Wilt, so you’ll need to split the base of the soybean stem to know if the problem is an insect or disease. Once you split the stem, look for orange or white larvae.
You can see in this photo by Dr. Bruce Potter from the University of Minnesota that the larvae look like maggots. If find larvae, contact your local Extension Service immediately! While SGM larvae are almost impossible to control once they have colonized plants, Extension personnel want to learn more about this pest’s lifecycle. Any information you can give on how your field may have been infested will help all of us combat this pest in future years.
Because so many soybeans across Latham Country were planted later this spring than in 2018, the concern is SGM might be even more problematic this year. Last fall SGM was recorded in 69 counties of Nebraska, Iowa, Minnesota and South Dakota.
Very little is known about the biology of the Soybean Gall Midge and even less is known about methods to control it. With your help, we can begin to know and understand more about this potential threat to soybean production.
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Latham Hi‑Tech Seeds
#AskTheAgronomist: Fungicide & Insecticide Application Thresholds
What is the threshold for applying fungicide on your corn? Tune in for discussion on mid-season fungicide and insecticide application with Phil Long! #AskTheAgronomist -
Latham Hi‑Tech Seeds
Soybean Aphids
Photo credit to Purdue University Soybean aphids can reduce yield by 10 to 15%. The insect is found in soybeans between May and August and are less than 1/16 inches long. Aphids have yellow bodies with a translucent appearance and may be winged or wingless.
Unlike other soybean insects, female aphids can produce clones and can multiply the insect population during the summer months. With the rapid reproduction abilities of female aphids, it is possible for populations to double in as little as two to three days. Males typically do not appear for mating until the late summer.
Apart from reproduction, environmental conditions that fuel infestation can also lead to a rapid increase in aphid populations. Temperatures between 72 and 77° and humidity below 78% drive the development of aphids. Drought conditions also make soybeans more susceptible to infestation.
Implications for Yield
Yield loss from aphids is attributed to the damage caused from feeding on leaves. Their destructive leaf feeding can reduce plant vigor and overall stand along with pod and seed populations.
Aside from feeding damage, waste produced from aphid feeding can leave a soot-like mold on the surface of leaves and reduce photosynthetic leaf area.
Scouting for Aphids
Aphids are most often found on the backside of the newest leaves, especially during the earliest part of the summer when the insect first emerges. Sampling for aphids should begin once the first signs of the insect are spotted. It is recommended to sample 20 to 30 plants across many areas of the field.
As the insect population increases, aphids can begin to inhabit the entire leaf canopy. If aphids are spotted on stems, this is a sign that aphid populations are above 400 insects per plant – an amount considered to be excessive. Be sure to scout for symptoms at least every 7-10 days until R6.
Management
Treatment of soybean aphids is advised if more than 80% of plants are infested and counts are in excess of 250 aphids per plant. Also, if it is evident that the population of the insect is increasing, this is also grounds for beginning treatment.
Foliar insecticides are the best method for combatting aphid populations in soybeans. In addition, biological control plays a role in staving off high aphid populations including pirate bugs and Asian ladybird beetles. When assessing the best treatment options for soybean aphids, be sure to consult with your local Latham representative.
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Latham Hi‑Tech Seeds
#AskTheAgronomist: Soybean Scouting Blitz
It’s time to scout soybeans!! Tune in for a 10 minute soybean blitz on what to look for in the field.
Insects: Japanese Beetles 1:55 Insects: Gall Midge 2:35 Insects: Aphids 3:55 Diseases: Sudden Death Syndrome 4:45 Diseases: Frog Eye 6:10 Diseases: Soybean Cyst Nematode 7:14 Disorders: Iron Deficiency Chlorosis 8:22 Disorders: Root Development 9:33 Disorders: Herbicide Injury 10:55 -
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Corn Aphids
Credit: Purdue University Corn aphids have the ability to negatively impact yield end of year. Proper identification and management can protect your crop.
Identification
Corn aphids have a blue-green to gray appearance and are 1/16 inch in length. Aphids extract sap from corn plants and excrete honeydew. The honeydew creates sooty-looking mold that can interfere with pollination.
As opposed to laying eggs, female aphids reproduce by giving birth to nymphs. The insects can build large colonies comprised of more than one species such as bird-cherry oat aphids. Aphids are most often wingless, but when the size of their colonies begin to grow, some can form wings to migrate to other corn plants. Corn leaf aphids cannot overwinter and usually migrate to southern states ahead of the cold months.
Scouting and Implications
Aphids will begin to appear in corn around mid-June and early July. Mature aphids can be found near the tassels, silks and the base of the corn stalk. The insects predominately live in the whorls where they are protected from outside elements. Infected corn plants may exhibit stunting or wilting and curling of the leaves
When scouting for aphids, select 20 non-consecutive plants from five different areas of the field. Unroll the whorl to count the number of insects present. The general treatment threshold advised by Iowa State University is when 50% of corn plants have more than 100 aphids per plant.
Overall, aphid infestations have been found to reduce grain quality and decrease kernel size. A study from Penn State University finds that 30-40% of aphid-infested corn stalks will become barren or earless. Drought stress can also worsen the impacts of aphid feeding and should be included when considering a treatment plan.
Treatment Options
The best time to begin manage aphid-infested corn is two to three weeks prior to tasseling. Corn plants with aphid colonies above the ear are more susceptible to yield loss than plants with aphids found below the ear.
Since aphids mainly colonize inside corn whorls, spraying insecticides is not the most effective solution. Insecticide application is most effective when aphids are found on the outermost areas of leaves. If corn plants that have reached the hard dent stage, applying insecticides will not pay.
Fungi and other beneficial insects including lacewings and lady beetles can reduce aphid populations. Look for signs of bloating or discoloration in aphids – this could be evidence of fungi at work. If over 20% of aphids appear to be parasitized, consider holding off on a management plan. Be sure to talk with your local Latham representative to develop an effective treatment strategy for managing aphids.
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Latham Hi‑Tech Seeds
Japanese Beetle in Corn and Soybeans
Credit: Purdue University Japanese beetles cause damage to corn by interfering with pollination and lead to defoliation in soybeans. Their distinct metallic-green heads and bronze wings make them distinguishable from other look-alike beetles. The insect undergoes one life cycle per year with adults reaching 5/16 inches in length.
Eggs are laid during July and August and overwinter until temperatures rise in the spring. For both corn and soybeans, adults migrate from grass and begin feeding in late May or early June. The peak emergence for Japanese beetles occurs 4 to 5 weeks after feeding begins.
Japanese beetles tend to feed in concentrated areas and in groups. After the female burrows into the soil, she will lay 1 to 4 eggs at a time for several weeks. Adult grubs feed on turf grass in late summer and early spring before emerging to feed on crops.
Corn In corn, Japanese beetles can feed on silks and interfere with pollination. Though leaf feeding in corn is possible, a majority of the economic impacts are attributed to silk feeding. Plants should be treated if there are three or more beetles per ear.
Research from the University of Tennessee found that repeated clipping of silks did not always lead to yield loss. More importantly, the environment has a stronger influence on the damage Japanese beetles can cause. Higher yield loss in infested corn plants that were under drought stress as opposed to plants that were not.
Soybeans
In soybeans, the beetle strictly feeds on the soft tissue bordering leaf veins, leaving them skeletonized. Soybeans growing in sandy soils are even more susceptible to defoliation from Japanese beetles. Though yield loss from Japanese beetles has not been quantified, figures from North Dakota State University (see table) point to the general yield impacts from defoliation. Research from the University of Nebraska advises treatment when damage reaches 30% defoliation before bloom or 20% defoliation during flowering. As long as beetles appear to be actively feeding, insecticide application is advised.
Other Considerations
Japanese beetles are easily confused with other species of beetles, including masked chafers and May or June beetles. Be sure to consult with your local Latham representative to confirm suspected Japanese beetle infestations and determine the right treatment plan.
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Photo Credit: Purdue University
